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The INIT_TASK() initializer was similarly confused about the stack vs thread_info allocation that the allocators had, and that were fixed in commit 
Linus Torvalds
commited |
7f1a00b6fc | |
The cputime can only be updated by the current task itself, even in vtime case. So we can safely use seqcount instead of seqlock as there is no writer concurrency involved. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Christoph Lameter <cl@linux.com> Cc: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1447948054-28668-8-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org> 
Frederic Weisbecker
authored and
 Ingo Molnar
commited |
b7ce2277f0 | |
Pull cgroup updates from Tejun Heo:
"The cgroup core saw several significant updates this cycle:
- percpu_rwsem for threadgroup locking is reinstated. This was
temporarily dropped due to down_write latency issues. Oleg's
rework of percpu_rwsem which is scheduled to be merged in this
merge window resolves the issue.
- On the v2 hierarchy, when controllers are enabled and disabled, all
operations are atomic and can fail and revert cleanly. This allows
->can_attach() failure which is necessary for cpu RT slices.
- Tasks now stay associated with the original cgroups after exit
until released. This allows tracking resources held by zombies
(e.g. pids) and makes it easy to find out where zombies came from
on the v2 hierarchy. The pids controller was broken before these
changes as zombies escaped the limits; unfortunately, updating this
behavior required too many invasive changes and I don't think it's
a good idea to backport them, so the pids controller on 4.3, the
first version which included the pids controller, will stay broken
at least until I'm sure about the cgroup core changes.
- Optimization of a couple common tests using static_key"
* 'for-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (38 commits)
cgroup: fix race condition around termination check in css_task_iter_next()
blkcg: don't create "io.stat" on the root cgroup
cgroup: drop cgroup__DEVEL__legacy_files_on_dfl
cgroup: replace error handling in cgroup_init() with WARN_ON()s
cgroup: add cgroup_subsys->free() method and use it to fix pids controller
cgroup: keep zombies associated with their original cgroups
cgroup: make css_set_rwsem a spinlock and rename it to css_set_lock
cgroup: don't hold css_set_rwsem across css task iteration
cgroup: reorganize css_task_iter functions
cgroup: factor out css_set_move_task()
cgroup: keep css_set and task lists in chronological order
cgroup: make cgroup_destroy_locked() test cgroup_is_populated()
cgroup: make css_sets pin the associated cgroups
cgroup: relocate cgroup_[try]get/put()
cgroup: move check_for_release() invocation
cgroup: replace cgroup_has_tasks() with cgroup_is_populated()
cgroup: make cgroup->nr_populated count the number of populated css_sets
cgroup: remove an unused parameter from cgroup_task_migrate()
cgroup: fix too early usage of static_branch_disable()
cgroup: make cgroup_update_dfl_csses() migrate all target processes atomically
...
Linus Torvalds
commited |
69234acee5 | |
It was found while running a database workload on large systems that significant time was spent trying to acquire the sighand lock. The issue was that whenever an itimer expired, many threads ended up simultaneously trying to send the signal. Most of the time, nothing happened after acquiring the sighand lock because another thread had just already sent the signal and updated the "next expire" time. The fastpath_timer_check() didn't help much since the "next expire" time was updated after the threads exit fastpath_timer_check(). This patch addresses this by having the thread_group_cputimer structure maintain a boolean to signify when a thread in the group is already checking for process wide timers, and adds extra logic in the fastpath to check the boolean. Signed-off-by: Jason Low <jason.low2@hp.com> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: George Spelvin <linux@horizon.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: hideaki.kimura@hpe.com Cc: terry.rudd@hpe.com Cc: scott.norton@hpe.com Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1444849677-29330-5-git-send-email-jason.low2@hp.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> 
Jason Low
authored and
 Thomas Gleixner
commited |
c8d75aa47d | |
In the next patch in this series, a new field 'checking_timer' will be added to 'struct thread_group_cputimer'. Both this and the existing 'running' integer field are just used as boolean values. To save space in the structure, we can make both of these fields booleans. This is a preparatory patch to convert the existing running integer field to a boolean. Suggested-by: George Spelvin <linux@horizon.com> Signed-off-by: Jason Low <jason.low2@hp.com> Reviewed: George Spelvin <linux@horizon.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: hideaki.kimura@hpe.com Cc: terry.rudd@hpe.com Cc: scott.norton@hpe.com Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1444849677-29330-4-git-send-email-jason.low2@hp.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Jason Low
authored and
Thomas Gleixner
commited |
d5c373eb56 | |
Note: This commit was originally committed as 
Tejun Heo
commited |
1ed1328792 | |
This reverts commit
Tejun Heo
commited |
0c986253b9 | |
While the current code guarantees monotonicity for stime and utime independently of one another, it does not guarantee that the sum of both is equal to the total time we started out with. This confuses things (and peoples) who look at this sum, like top, and will report >100% usage followed by a matching period of 0%. Rework the code to provide both individual monotonicity and a coherent sum. Suggested-by: Fredrik Markstrom <fredrik.markstrom@gmail.com> Reported-by: Fredrik Markstrom <fredrik.markstrom@gmail.com> Tested-by: Fredrik Markstrom <fredrik.markstrom@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Stanislaw Gruszka <sgruszka@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: jason.low2@hp.com Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> 
Peter Zijlstra
authored and
Ingo Molnar
commited |
9d7fb04276 | |
Pull cgroup updates from Tejun Heo: - threadgroup_lock got reorganized so that its users can pick the actual locking mechanism to use. Its only user - cgroups - is updated to use a percpu_rwsem instead of per-process rwsem. This makes things a bit lighter on hot paths and allows cgroups to perform and fail multi-task (a process) migrations atomically. Multi-task migrations are used in several places including the unified hierarchy. - Delegation rule and documentation added to unified hierarchy. This will likely be the last interface update from the cgroup core side for unified hierarchy before lifting the devel mask. - Some groundwork for the pids controller which is scheduled to be merged in the coming devel cycle. * 'for-4.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: add delegation section to unified hierarchy documentation cgroup: require write perm on common ancestor when moving processes on the default hierarchy cgroup: separate out cgroup_procs_write_permission() from __cgroup_procs_write() kernfs: make kernfs_get_inode() public MAINTAINERS: add a cgroup core co-maintainer cgroup: fix uninitialised iterator in for_each_subsys_which cgroup: replace explicit ss_mask checking with for_each_subsys_which cgroup: use bitmask to filter for_each_subsys cgroup: add seq_file forward declaration for struct cftype cgroup: simplify threadgroup locking sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem sched, cgroup: reorganize threadgroup locking cgroup: switch to unsigned long for bitmasks cgroup: reorganize include/linux/cgroup.h cgroup: separate out include/linux/cgroup-defs.h cgroup: fix some comment typos
Linus Torvalds
commited |
bbe179f88d | |
The cgroup side of threadgroup locking uses signal_struct->group_rwsem to synchronize against threadgroup changes. This per-process rwsem adds small overhead to thread creation, exit and exec paths, forces cgroup code paths to do lock-verify-unlock-retry dance in a couple places and makes it impossible to atomically perform operations across multiple processes. This patch replaces signal_struct->group_rwsem with a global percpu_rwsem cgroup_threadgroup_rwsem which is cheaper on the reader side and contained in cgroups proper. This patch converts one-to-one. This does make writer side heavier and lower the granularity; however, cgroup process migration is a fairly cold path, we do want to optimize thread operations over it and cgroup migration operations don't take enough time for the lower granularity to matter. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org>
Tejun Heo
commited |
d59cfc09c3 | |
Recent optimizations were made to thread_group_cputimer to improve its scalability by keeping track of cputime stats without a lock. However, the values were open coded to the structure, causing them to be at a different abstraction level from the regular task_cputime structure. Furthermore, any subsequent similar optimizations would not be able to share the new code, since they are specific to thread_group_cputimer. This patch adds the new task_cputime_atomic data structure (introduced in the previous patch in the series) to thread_group_cputimer for keeping track of the cputime atomically, which also helps generalize the code. Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Jason Low <jason.low2@hp.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Aswin Chandramouleeswaran <aswin@hp.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com> Cc: Scott J Norton <scott.norton@hp.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Waiman Long <Waiman.Long@hp.com> Link: http://lkml.kernel.org/r/1430251224-5764-6-git-send-email-jason.low2@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Jason Low
authored and
Ingo Molnar
commited |
7110744516 | |
While running a database workload, we found a scalability issue with itimers. Much of the problem was caused by the thread_group_cputimer spinlock. Each time we account for group system/user time, we need to obtain a thread_group_cputimer's spinlock to update the timers. On larger systems (such as a 16 socket machine), this caused more than 30% of total time spent trying to obtain this kernel lock to update these group timer stats. This patch converts the timers to 64-bit atomic variables and use atomic add to update them without a lock. With this patch, the percent of total time spent updating thread group cputimer timers was reduced from 30% down to less than 1%. Note: On 32-bit systems using the generic 64-bit atomics, this causes sample_group_cputimer() to take locks 3 times instead of just 1 time. However, we tested this patch on a 32-bit system ARM system using the generic atomics and did not find the overhead to be much of an issue. An explanation for why this isn't an issue is that 32-bit systems usually have small numbers of CPUs, and cacheline contention from extra spinlocks called periodically is not really apparent on smaller systems. Signed-off-by: Jason Low <jason.low2@hp.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Aswin Chandramouleeswaran <aswin@hp.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com> Cc: Scott J Norton <scott.norton@hp.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Waiman Long <Waiman.Long@hp.com> Link: http://lkml.kernel.org/r/1430251224-5764-4-git-send-email-jason.low2@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Jason Low
authored and
Ingo Molnar
commited |
1018016c70 | |
Stack instrumentation allows to detect out of bounds memory accesses for variables allocated on stack. Compiler adds redzones around every variable on stack and poisons redzones in function's prologue. Such approach significantly increases stack usage, so all in-kernel stacks size were doubled. Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Serebryany <kcc@google.com> Cc: Dmitry Chernenkov <dmitryc@google.com> Signed-off-by: Andrey Konovalov <adech.fo@gmail.com> Cc: Yuri Gribov <tetra2005@gmail.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Christoph Lameter <cl@linux.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Andrey Ryabinin
authored and
Linus Torvalds
commited |
c420f167db | |
If an attacker can cause a controlled kernel stack overflow, overwriting the restart block is a very juicy exploit target. This is because the restart_block is held in the same memory allocation as the kernel stack. Moving the restart block to struct task_struct prevents this exploit by making the restart_block harder to locate. Note that there are other fields in thread_info that are also easy targets, at least on some architectures. It's also a decent simplification, since the restart code is more or less identical on all architectures. [james.hogan@imgtec.com: metag: align thread_info::supervisor_stack] Signed-off-by: Andy Lutomirski <luto@amacapital.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: David Miller <davem@davemloft.net> Acked-by: Richard Weinberger <richard@nod.at> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Matt Turner <mattst88@gmail.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Haavard Skinnemoen <hskinnemoen@gmail.com> Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no> Cc: Steven Miao <realmz6@gmail.com> Cc: Mark Salter <msalter@redhat.com> Cc: Aurelien Jacquiot <a-jacquiot@ti.com> Cc: Mikael Starvik <starvik@axis.com> Cc: Jesper Nilsson <jesper.nilsson@axis.com> Cc: David Howells <dhowells@redhat.com> Cc: Richard Kuo <rkuo@codeaurora.org> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Michal Simek <monstr@monstr.eu> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Jonas Bonn <jonas@southpole.se> Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Helge Deller <deller@gmx.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Tested-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Chen Liqin <liqin.linux@gmail.com> Cc: Lennox Wu <lennox.wu@gmail.com> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Guan Xuetao <gxt@mprc.pku.edu.cn> Cc: Chris Zankel <chris@zankel.net> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Guenter Roeck <linux@roeck-us.net> Signed-off-by: James Hogan <james.hogan@imgtec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Andy Lutomirski
authored and
Linus Torvalds
commited |
f56141e3e2 | |
Pull scheduler updates from Ingo Molnar:
"The main changes in this cycle are:
- 'Nested Sleep Debugging', activated when CONFIG_DEBUG_ATOMIC_SLEEP=y.
This instruments might_sleep() checks to catch places that nest
blocking primitives - such as mutex usage in a wait loop. Such
bugs can result in hard to debug races/hangs.
Another category of invalid nesting that this facility will detect
is the calling of blocking functions from within schedule() ->
sched_submit_work() -> blk_schedule_flush_plug().
There's some potential for false positives (if secondary blocking
primitives themselves are not ready yet for this facility), but the
kernel will warn once about such bugs per bootup, so the warning
isn't much of a nuisance.
This feature comes with a number of fixes, for problems uncovered
with it, so no messages are expected normally.
- Another round of sched/numa optimizations and refinements, for
CONFIG_NUMA_BALANCING=y.
- Another round of sched/dl fixes and refinements.
Plus various smaller fixes and cleanups"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (54 commits)
sched: Add missing rcu protection to wake_up_all_idle_cpus
sched/deadline: Introduce start_hrtick_dl() for !CONFIG_SCHED_HRTICK
sched/numa: Init numa balancing fields of init_task
sched/deadline: Remove unnecessary definitions in cpudeadline.h
sched/cpupri: Remove unnecessary definitions in cpupri.h
sched/deadline: Fix rq->dl.pushable_tasks bug in push_dl_task()
sched/fair: Fix stale overloaded status in the busiest group finding logic
sched: Move p->nr_cpus_allowed check to select_task_rq()
sched/completion: Document when to use wait_for_completion_io_*()
sched: Update comments about CLONE_NEWUTS and CLONE_NEWIPC
sched/fair: Kill task_struct::numa_entry and numa_group::task_list
sched: Refactor task_struct to use numa_faults instead of numa_* pointers
sched/deadline: Don't check CONFIG_SMP in switched_from_dl()
sched/deadline: Reschedule from switched_from_dl() after a successful pull
sched/deadline: Push task away if the deadline is equal to curr during wakeup
sched/deadline: Add deadline rq status print
sched/deadline: Fix artificial overrun introduced by yield_task_dl()
sched/rt: Clean up check_preempt_equal_prio()
sched/core: Use dl_bw_of() under rcu_read_lock_sched()
sched: Check if we got a shallowest_idle_cpu before searching for least_loaded_cpu
...
Linus Torvalds
commited |
86c6a2fddf | |
We do not initialize init_task.numa_preferred_nid,
but this value is inherited by userspace "init"
process:
rest_init()->kernel_thread(kernel_init)->do_fork(CLONE_VM);
__sched_fork()
{
if (clone_flags & CLONE_VM)
p->numa_preferred_nid = current->numa_preferred_nid;
else
p->numa_preferred_nid = -1;
}
kernel_init() becomes userspace "init" process.
So, we propagate garbage nid to userspace, and it may be used
during numa balancing.
Currently, we do not have reports about this brings a problem,
but it seem we should set it for sure.
Even if init_task.numa_preferred_nid is zero, we may meet a weird
configuration without nid#0. On sparc64, where processors are
numbered physically, I saw a machine without cpu#1, while cpu#2
existed. Possible, something similar may be with numa nodes.
So, let's initialize it and be sure we're safe.
Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Eric Paris <eparis@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Sergey Dyasly <dserrg@gmail.com>
Link: http://lkml.kernel.org/r/1415699189.15631.6.camel@tkhai
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Kirill Tkhai
authored and
Ingo Molnar
commited |
d8b163c4c6 | |
PREEMPT_RCU and TREE_PREEMPT_RCU serve the same function after TINY_PREEMPT_RCU has been removed. This patch removes TREE_PREEMPT_RCU and uses PREEMPT_RCU config option in its place. Signed-off-by: Pranith Kumar <bobby.prani@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> 
Pranith Kumar
authored and
 Paul E. McKenney
commited |
28f6569ab7 | |
The rcu_preempt_note_context_switch() function is on a scheduling fast path, so it would be good to avoid disabling irqs. The reason that irqs are disabled is to synchronize process-level and irq-handler access to the task_struct ->rcu_read_unlock_special bitmask. This commit therefore makes ->rcu_read_unlock_special instead be a union of bools with a short allowing single-access checks in RCU's __rcu_read_unlock(). This results in the process-level and irq-handler accesses being simple loads and stores, so that irqs need no longer be disabled. This commit therefore removes the irq disabling from rcu_preempt_note_context_switch(). Reported-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Paul E. McKenney
commited |
1d082fd061 | |
Currently TASKS_RCU would ignore a CPU running a task in nohz_full= usermode execution. There would be neither a context switch nor a scheduling-clock interrupt to tell TASKS_RCU that the task in question had passed through a quiescent state. The grace period would therefore extend indefinitely. This commit therefore makes RCU's dyntick-idle subsystem record the task_struct structure of the task that is running in dyntick-idle mode on each CPU. The TASKS_RCU grace period can then access this information and record a quiescent state on behalf of any CPU running in dyntick-idle usermode. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Paul E. McKenney
commited |
176f8f7a52 | |
This commit adds a new RCU-tasks flavor of RCU, which provides call_rcu_tasks(). This RCU flavor's quiescent states are voluntary context switch (not preemption!) and userspace execution (not the idle loop -- use some sort of schedule_on_each_cpu() if you need to handle the idle tasks. Note that unlike other RCU flavors, these quiescent states occur in tasks, not necessarily CPUs. Includes fixes from Steven Rostedt. This RCU flavor is assumed to have very infrequent latency-tolerant updaters. This assumption permits significant simplifications, including a single global callback list protected by a single global lock, along with a single task-private linked list containing all tasks that have not yet passed through a quiescent state. If experience shows this assumption to be incorrect, the required additional complexity will be added. Suggested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Paul E. McKenney
commited |
8315f42295 | |
RCU priority boosting currently checks for boosting via a pointer in task_struct. However, this is not needed: As Oleg noted, if the rt_mutex is placed in the rcu_node instead of on the booster's stack, the boostee can simply check it see if it owns the lock. This commit makes this change, shrinking task_struct by one pointer and the kernel by thirteen lines. Suggested-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Paul E. McKenney
commited |
abaa93d9e1 | |
Pull audit update from Eric Paris: "Again we stayed pretty well contained inside the audit system. Venturing out was fixing a couple of function prototypes which were inconsistent (didn't hurt anything, but we used the same value as an int, uint, u32, and I think even a long in a couple of places). We also made a couple of minor changes to when a couple of LSMs called the audit system. We hoped to add aarch64 audit support this go round, but it wasn't ready. I'm disappearing on vacation on Thursday. I should have internet access, but it'll be spotty. If anything goes wrong please be sure to cc rgb@redhat.com. He'll make fixing things his top priority" * git://git.infradead.org/users/eparis/audit: (50 commits) audit: whitespace fix in kernel-parameters.txt audit: fix location of __net_initdata for audit_net_ops audit: remove pr_info for every network namespace audit: Modify a set of system calls in audit class definitions audit: Convert int limit uses to u32 audit: Use more current logging style audit: Use hex_byte_pack_upper audit: correct a type mismatch in audit_syscall_exit() audit: reorder AUDIT_TTY_SET arguments audit: rework AUDIT_TTY_SET to only grab spin_lock once audit: remove needless switch in AUDIT_SET audit: use define's for audit version audit: documentation of audit= kernel parameter audit: wait_for_auditd rework for readability audit: update MAINTAINERS audit: log task info on feature change audit: fix incorrect set of audit_sock audit: print error message when fail to create audit socket audit: fix dangling keywords in audit_log_set_loginuid() output audit: log on errors from filter user rules ...
Linus Torvalds
commited |
6dd9158ae8 | |
while_each_thread() and next_thread() should die, almost every lockless usage is wrong. 1. Unless g == current, the lockless while_each_thread() is not safe. while_each_thread(g, t) can loop forever if g exits, next_thread() can't reach the unhashed thread in this case. Note that this can happen even if g is the group leader, it can exec. 2. Even if while_each_thread() itself was correct, people often use it wrongly. It was never safe to just take rcu_read_lock() and loop unless you verify that pid_alive(g) == T, even the first next_thread() can point to the already freed/reused memory. This patch adds signal_struct->thread_head and task->thread_node to create the normal rcu-safe list with the stable head. The new for_each_thread(g, t) helper is always safe under rcu_read_lock() as long as this task_struct can't go away. Note: of course it is ugly to have both task_struct->thread_node and the old task_struct->thread_group, we will kill it later, after we change the users of while_each_thread() to use for_each_thread(). Perhaps we can kill it even before we convert all users, we can reimplement next_thread(t) using the new thread_head/thread_node. But we can't do this right now because this will lead to subtle behavioural changes. For example, do/while_each_thread() always sees at least one task, while for_each_thread() can do nothing if the whole thread group has died. Or thread_group_empty(), currently its semantics is not clear unless thread_group_leader(p) and we need to audit the callers before we can change it. So this patch adds the new interface which has to coexist with the old one for some time, hopefully the next changes will be more or less straightforward and the old one will go away soon. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: Sergey Dyasly <dserrg@gmail.com> Tested-by: Sergey Dyasly <dserrg@gmail.com> Reviewed-by: Sameer Nanda <snanda@chromium.org> Acked-by: David Rientjes <rientjes@google.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Mandeep Singh Baines <msb@chromium.org> Cc: "Ma, Xindong" <xindong.ma@intel.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: "Tu, Xiaobing" <xiaobing.tu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Oleg Nesterov
authored and
Linus Torvalds
commited |
0c740d0afc | |
Right now the sessionid value in the kernel is a combination of u32, int, and unsigned int. Just use unsigned int throughout. Signed-off-by: Eric Paris <eparis@redhat.com> Signed-off-by: Richard Guy Briggs <rgb@redhat.com> Signed-off-by: Eric Paris <eparis@redhat.com> 
Eric Paris
commited |
4440e85481 | |
Turn the pi-chains from plist to rb-tree, in the rt_mutex code, and provide a proper comparison function for -deadline and -priority tasks. This is done mainly because: - classical prio field of the plist is just an int, which might not be enough for representing a deadline; - manipulating such a list would become O(nr_deadline_tasks), which might be to much, as the number of -deadline task increases. Therefore, an rb-tree is used, and tasks are queued in it according to the following logic: - among two -priority (i.e., SCHED_BATCH/OTHER/RR/FIFO) tasks, the one with the higher (lower, actually!) prio wins; - among a -priority and a -deadline task, the latter always wins; - among two -deadline tasks, the one with the earliest deadline wins. Queueing and dequeueing functions are changed accordingly, for both the list of a task's pi-waiters and the list of tasks blocked on a pi-lock. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Dario Faggioli <raistlin@linux.it> Signed-off-by: Juri Lelli <juri.lelli@gmail.com> Signed-off-again-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1383831828-15501-10-git-send-email-juri.lelli@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Peter Zijlstra
authored and
Ingo Molnar
commited |
fb00aca474 | |
Currently seqlocks and seqcounts don't support lockdep. After running across a seqcount related deadlock in the timekeeping code, I used a less-refined and more focused variant of this patch to narrow down the cause of the issue. This is a first-pass attempt to properly enable lockdep functionality on seqlocks and seqcounts. Since seqcounts are used in the vdso gettimeofday code, I've provided non-lockdep accessors for those needs. I've also handled one case where there were nested seqlock writers and there may be more edge cases. Comments and feedback would be appreciated! Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Li Zefan <lizefan@huawei.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: netdev@vger.kernel.org Link: http://lkml.kernel.org/r/1381186321-4906-3-git-send-email-john.stultz@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org> 
John Stultz
authored and
Ingo Molnar
commited |
1ca7d67cf5 | |
IA64 relied on it through sched.h inclusion: arch/ia64/kernel/init_task.c:38:11: error: 'MAX_PRIO' undeclared here (not in a function) arch/ia64/kernel/init_task.c:38:11: error: 'RR_TIMESLICE' undeclared here (not in a function) Reported-by: kbuild test robot <fengguang.wu@intel.com> Cc: Clark Williams <williams@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/n/tip-xaan1twswggedMR0airtpjui@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Ingo Molnar
commited |
77852fea6e | |
While remotely reading the cputime of a task running in a full dynticks CPU, the values stored in utime/stime fields of struct task_struct may be stale. Its values may be those of the last kernel <-> user transition time snapshot and we need to add the tickless time spent since this snapshot. To fix this, flush the cputime of the dynticks CPUs on kernel <-> user transition and record the time / context where we did this. Then on top of this snapshot and the current time, perform the fixup on the reader side from task_times() accessors. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> [fixed kvm module related build errors] Signed-off-by: Sedat Dilek <sedat.dilek@gmail.com>
Frederic Weisbecker
commited |
6a61671bb2 | |
Always store audit loginuids in type kuid_t. Print loginuids by converting them into uids in the appropriate user namespace, and then printing the resulting uid. Modify audit_get_loginuid to return a kuid_t. Modify audit_set_loginuid to take a kuid_t. Modify /proc/<pid>/loginuid on read to convert the loginuid into the user namespace of the opener of the file. Modify /proc/<pid>/loginud on write to convert the loginuid rom the user namespace of the opener of the file. Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Eric Paris <eparis@redhat.com> Cc: Paul Moore <paul@paul-moore.com> ? Cc: David Miller <davem@davemloft.net> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> 
Eric W. Biederman
commited |
e1760bd5ff | |
Pull scheduler changes from Ingo Molnar: "The biggest change is a performance improvement on SMP systems: | 4 socket 40 core + SMT Westmere box, single 30 sec tbench | runs, higher is better: | | clients 1 2 4 8 16 32 64 128 |.......................................................................... | pre 30 41 118 645 3769 6214 12233 14312 | post 299 603 1211 2418 4697 6847 11606 14557 | | A nice increase in performance. which speedup is particularly noticeable on heavily interacting few-tasks workloads, so the changes should help desktop-style Xorg workloads and interactivity as well, on multi-core CPUs. There are also cpuset suspend behavior fixes/restructuring and various smaller tweaks." * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched: Fix race in task_group() sched: Improve balance_cpu() to consider other cpus in its group as target of (pinned) task sched: Reset loop counters if all tasks are pinned and we need to redo load balance sched: Reorder 'struct lb_env' members to reduce its size sched: Improve scalability via 'CPU buddies', which withstand random perturbations cpusets: Remove/update outdated comments cpusets, hotplug: Restructure functions that are invoked during hotplug cpusets, hotplug: Implement cpuset tree traversal in a helper function CPU hotplug, cpusets, suspend: Don't modify cpusets during suspend/resume sched/x86: Remove broken power estimation
Linus Torvalds
commited |
79071638ce | |
Stefan reported a crash on a kernel before
Peter Zijlstra
authored and
Ingo Molnar
commited |
8323f26ce3 | |
This commit applies the INIT_RCU_POINTER() macro to all uses of RCU_POINTER_INITIALIZER() that were all too cleverly creating gcc-style initializations. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: David Howells <dhowells@redhat.com>
Paul E. McKenney
commited |
d36cc701b2 | |
Since nr_cpus_allowed is used outside of sched/rt.c and wants to be used outside of there more, move it to a more natural site. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-kr61f02y9brwzkh6x53pdptm@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> 
Peter Zijlstra
authored and
Ingo Molnar
commited |
29baa7478b | |
Commit
Mel Gorman
authored and
Linus Torvalds
commited |
cc9a6c8776 | |
Current the initial SCHED_RR timeslice of init_task is HZ, which means 1s, and is not same as the default SCHED_RR timeslice DEF_TIMESLICE. Change that initial timeslice to the DEF_TIMESLICE. Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> [ s/DEF_TIMESLICE/RR_TIMESLICE/g ] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/4F3C9995.3010800@ct.jp.nec.com Signed-off-by: Ingo Molnar <mingo@elte.hu> 
Hiroshi Shimamoto
authored and
 Ingo Molnar
commited |
de5bdff7a7 | |
* 'for-3.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (21 commits)
cgroup: fix to allow mounting a hierarchy by name
cgroup: move assignement out of condition in cgroup_attach_proc()
cgroup: Remove task_lock() from cgroup_post_fork()
cgroup: add sparse annotation to cgroup_iter_start() and cgroup_iter_end()
cgroup: mark cgroup_rmdir_waitq and cgroup_attach_proc() as static
cgroup: only need to check oldcgrp==newgrp once
cgroup: remove redundant get/put of task struct
cgroup: remove redundant get/put of old css_set from migrate
cgroup: Remove unnecessary task_lock before fetching css_set on migration
cgroup: Drop task_lock(parent) on cgroup_fork()
cgroups: remove redundant get/put of css_set from css_set_check_fetched()
resource cgroups: remove bogus cast
cgroup: kill subsys->can_attach_task(), pre_attach() and attach_task()
cgroup, cpuset: don't use ss->pre_attach()
cgroup: don't use subsys->can_attach_task() or ->attach_task()
cgroup: introduce cgroup_taskset and use it in subsys->can_attach(), cancel_attach() and attach()
cgroup: improve old cgroup handling in cgroup_attach_proc()
cgroup: always lock threadgroup during migration
threadgroup: extend threadgroup_lock() to cover exit and exec
threadgroup: rename signal->threadgroup_fork_lock to ->group_rwsem
...
Fix up conflict in kernel/cgroup.c due to commit
Linus Torvalds
commited |
db0c2bf69a | |
Make the following renames to prepare for extension of threadgroup
locking.
* s/signal->threadgroup_fork_lock/signal->group_rwsem/
* s/threadgroup_fork_read_lock()/threadgroup_change_begin()/
* s/threadgroup_fork_read_unlock()/threadgroup_change_end()/
* s/threadgroup_fork_write_lock()/threadgroup_lock()/
* s/threadgroup_fork_write_unlock()/threadgroup_unlock()/
This patch doesn't cause any behavior change.
-v2: Rename threadgroup_change_done() to threadgroup_change_end() per
KAMEZAWA's suggestion.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul Menage <paul@paulmenage.org>
Tejun Heo
commited |
257058ae2b | |
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched, x86: Avoid unnecessary overflow in sched_clock sched: Fix buglet in return_cfs_rq_runtime() sched: Avoid SMT siblings in select_idle_sibling() if possible sched: Set the command name of the idle tasks in SMP kernels sched, rt: Provide means of disabling cross-cpu bandwidth sharing sched: Document wait_for_completion_*() return values sched_fair: Fix a typo in the comment describing update_sd_lb_stats sched: Add a comment to effective_load() since it's a pain
Linus Torvalds
commited |
7125faceab | |
They are not used any more. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> 
Wu Fengguang
commited |
468e6a20af | |
In UP systems, the idle task is initialized using the init_task structure from which the command name is taken (currently "swapper"). In SMP systems, one idle task per CPU is forked by the worker thread from which the task structure is copied. The command name is, therefore, "kworker/0:0" or "kworker/0:1", if not updated. Since such update was lacking, all idle tasks in SMP systems were incorrectly named. This longtime bug was not discovered immediately, because there is no /proc/0 entry - the bug only becomes apparent when tracing is enabled. This patch sets the command name of the idle tasks in SMP systems to the name that is used in the INIT_TASK structure suffixed by a slash and the number of the CPU. Signed-off-by: Carsten Emde <C.Emde@osadl.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20111026211708.768925506@osadl.org Signed-off-by: Ingo Molnar <mingo@elte.hu> 
Carsten Emde
authored and
Ingo Molnar
commited |
f1c6f1a7ee | |
The thread_group_cputimer lock can be taken in atomic context and therefore cannot be preempted on -rt - annotate it. In mainline this change documents the low level nature of the lock - otherwise there's no functional difference. Lockdep and Sparse checking will work as usual. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Thomas Gleixner
authored and
Ingo Molnar
commited |
ee30a7b2fc | |
fs_excl is a poor man's priority inheritance for filesystems to hint to the block layer that an operation is important. It was never clearly specified, not widely adopted, and will not prevent starvation in many cases (like across cgroups). fs_excl was introduced with the time sliced CFQ IO scheduler, to indicate when a process held FS exclusive resources and thus needed a boost. It doesn't cover all file systems, and it was never fully complete. Lets kill it. Signed-off-by: Justin TerAvest <teravest@google.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com> 
Justin TerAvest
authored and
 Jens Axboe
commited |
4aede84b33 | |
Adds functionality to read/write lock CLONE_THREAD fork()ing per-threadgroup Add an rwsem that lives in a threadgroup's signal_struct that's taken for reading in the fork path, under CONFIG_CGROUPS. If another part of the kernel later wants to use such a locking mechanism, the CONFIG_CGROUPS ifdefs should be changed to a higher-up flag that CGROUPS and the other system would both depend on. This is a pre-patch for cgroup-procs-write.patch. Signed-off-by: Ben Blum <bblum@andrew.cmu.edu> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Matt Helsley <matthltc@us.ibm.com> Reviewed-by: Paul Menage <menage@google.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Ben Blum
authored and
Linus Torvalds
commited |
4714d1d32d | |
James Morris
commited |
434d42cfd0 | |
Neil Brown pointed out that lock_depth somehow escaped the BKL removal work. Let's get rid of it now. Note that the perf scripting utilities still have a bunch of code for dealing with common_lock_depth in tracepoints; I have left that in place in case anybody wants to use that code with older kernels. Suggested-by: Neil Brown <neilb@suse.de> Signed-off-by: Jonathan Corbet <corbet@lwn.net> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20110422111910.456c0e84@bike.lwn.net Signed-off-by: Ingo Molnar <mingo@elte.hu> 
Jonathan Corbet
authored and
Ingo Molnar
commited |
625f2a378e | |
The CAP_INIT macros of INH, BSET, and EFF made sense at one point in time, but now days they aren't helping. Just open code the logic in the init_cred. Signed-off-by: Eric Paris <eparis@redhat.com> Acked-by: David Howells <dhowells@redhat.com> Signed-off-by: James Morris <jmorris@namei.org>
Eric Paris
authored and
James Morris
commited |
a3232d2fa2 | |
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (30 commits)
sched: Change wait_for_completion_*_timeout() to return a signed long
sched, autogroup: Fix reference leak
sched, autogroup: Fix potential access to freed memory
sched: Remove redundant CONFIG_CGROUP_SCHED ifdef
sched: Fix interactivity bug by charging unaccounted run-time on entity re-weight
sched: Move periodic share updates to entity_tick()
printk: Use this_cpu_{read|write} api on printk_pending
sched: Make pushable_tasks CONFIG_SMP dependant
sched: Add 'autogroup' scheduling feature: automated per session task groups
sched: Fix unregister_fair_sched_group()
sched: Remove unused argument dest_cpu to migrate_task()
mutexes, sched: Introduce arch_mutex_cpu_relax()
sched: Add some clock info to sched_debug
cpu: Remove incorrect BUG_ON
cpu: Remove unused variable
sched: Fix UP build breakage
sched: Make task dump print all 15 chars of proc comm
sched: Update tg->shares after cpu.shares write
sched: Allow update_cfs_load() to update global load
sched: Implement demand based update_cfs_load()
...
Linus Torvalds
commited |
65b2074f84 | |
|
Ingo Molnar
commited |
394f4528c5 | |
As noted by Peter Zijlstra at https://lkml.org/lkml/2010/11/10/391 (while reviewing other stuff, though), tracking pushable tasks only makes sense on SMP systems. Signed-off-by: Dario Faggioli <raistlin@linux.it> Acked-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Gregory Haskins <ghaskins@novell.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1291143093.2697.298.camel@Palantir> Signed-off-by: Ingo Molnar <mingo@elte.hu> 
Dario Faggioli
authored and
Ingo Molnar
commited |
806c09a7db | |
Add priority boosting, but only for TINY_PREEMPT_RCU. This is enabled by the default-off RCU_BOOST kernel parameter. The priority to which to boost preempted RCU readers is controlled by the RCU_BOOST_PRIO kernel parameter (defaulting to real-time priority 1) and the time to wait before boosting the readers blocking a given grace period is controlled by the RCU_BOOST_DELAY kernel parameter (defaulting to 500 milliseconds). Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> 
Paul E. McKenney
commited |
24278d1483 |