|From:||Matt Fleming <email@example.com>|
|To:||Tejun Heo <firstname.lastname@example.org>, Oleg Nesterov <email@example.com>|
|Subject:||[RFC][PATCH 0/5] Improve signal delivery scalability|
|Date:||Tue, 5 Apr 2011 20:21:45 +0100|
|Cc:||firstname.lastname@example.org, Thomas Gleixner <email@example.com>, Peter Zijlstra <firstname.lastname@example.org>, "H. Peter Anvin" <email@example.com>, Matt Fleming <firstname.lastname@example.org>|
From: Matt Fleming <email@example.com> This series is most definitely RFC material. At this early stage I'm just asking for feedback on whether the concepts/ideas are sound. For example, I'm fairly sure that these patches break ia64 because it accesses tsk->pending in asm and I haven't had time to look closely at that yet. This patch series was motivated by the signal1_threads testcase from the Will It Scale benchmark suite. Currently, signal generation and delivery in a thread group is serialised by the thread group's siglock, tsk->sighand->siglock. This lock is a huge point of contention in multithreaded applications, even when sending a signal to one thread in a thread group. In light of this, this patch series tries to improve scalability by, - introducing a per-thread siglock to protect the per-thread pending signal queue - avoiding acquiring the shared siglock wherever possible - using a rwlock to protect signal handlers This series is based on the assumption that it is OK to acquire and release the shared siglock across function calls and do things like execute PENDING() without holding any locks. The improvement on the "signal delivery" testcase can be seen here, http://userweb.kernel.org/~mfleming/will-it-scale/signals... Tejun, these patches are based on your ptrace branch as both you and Oleg have touched alot of the same code paths lately. All comments appreciated! Matt Fleming (5): signals: Always place SIGCONT and SIGSTOP on 'shared_pending' signals: Introduce per-thread siglock and action rwlock ia64: Catch up with new sighand action spinlock signals: Introduce __dequeue_private_signal helper function signals: Don't hold shared siglock across signal delivery arch/ia64/kernel/signal.c | 13 +-- fs/autofs4/waitq.c | 2 + fs/exec.c | 2 + fs/signalfd.c | 7 +- include/linux/init_task.h | 2 + include/linux/sched.h | 4 + include/linux/signal.h | 5 + include/linux/tracehook.h | 3 +- kernel/compat.c | 7 +- kernel/exit.c | 12 +- kernel/fork.c | 2 + kernel/kmod.c | 8 +- kernel/ptrace.c | 4 +- kernel/signal.c | 429 +++++++++++++++++++++++++++++++++------------ security/selinux/hooks.c | 6 +- 15 files changed, 360 insertions(+), 146 deletions(-) -- 1.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to firstname.lastname@example.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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