Messages in this thread | | | From | Jason Low <> | Subject | [PATCH v2 0/4] timer: Improve itimers scalability | Date | Wed, 14 Oct 2015 12:07:52 -0700 |
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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(-)
-- 1.7.2.5
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