Re: [PATCH 0/3] timer: Improve itimers scalability

Andrew Morton
2015-08-26T03:27:11Z

On Tue, 25 Aug 2015 20:17:45 -0700 Jason Low <jason.low2@hp.com> wrote:

> When running a database workload on a 16 socket machine, there were
> scalability issues related to itimers.
>
> Commit 1018016c706f addressed the issue with the thread_group_cputimer
> spinlock taking up a significant portion of total run time.
>
> This patch series address the other 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%.

Does this imply that the patchset increased the throughput of this
workload by 30%?

And is this test case realistic? If not, what are the benefits on a
real-world workload?