Messages in this thread | | | Date | Thu, 15 Oct 2015 10:47:02 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH v2 0/4] timer: Improve itimers scalability |
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* Jason Low <jason.low2@hp.com> wrote:
> While running a database workload on a 16 socket machine, there were > scalability issues related to itimers. The following link contains a > more detailed summary of the issues at the application level. > > https://lkml.org/lkml/2015/8/26/737 > > Commit 1018016c706f addressed the issue with the thread_group_cputimer > spinlock taking up a significant portion of total run time. > This patch series addresses the secondary issue where a lot of time is > spent trying to acquire the sighand lock. It was found in some cases > that 200+ threads were simultaneously contending for the same sighand > lock, reducing throughput by more than 30%. > > With this patch set (along with commit 1018016c706f mentioned above), > the performance hit of itimers almost completely goes away on the > 16 socket system. > > Jason Low (4): > timer: Optimize fastpath_timer_check() > timer: Check thread timers only when there are active thread timers > timer: Convert cputimer->running to bool > timer: Reduce unnecessary sighand lock contention > > include/linux/init_task.h | 3 +- > include/linux/sched.h | 9 ++++-- > kernel/fork.c | 2 +- > kernel/time/posix-cpu-timers.c | 63 ++++++++++++++++++++++++++++----------- > 4 files changed, 54 insertions(+), 23 deletions(-)
Is there some itimers benchmark that can be used to measure the effects of these changes?
Thanks,
Ingo
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