On Sun, Nov 4, 2018 at 9:08 PM kernel test robot <[email protected]> wrote:
>
> FYI, we noticed a -64.1% regression of will-it-scale.per_thread_ops
> due to commit 9bc8039e715d ("mm: brk: downgrade mmap_sem to read when
> shrinking")
Ugh. That looks pretty bad.
> in testcase: will-it-scale
> on test machine: 8 threads Ivy Bridge with 16G memory
> with following parameters:
>
> nr_task: 100%
> mode: thread
> test: brk1
> ucode: 0x20
> cpufreq_governor: performance
The reason seems to be way more scheduler time due to lots more
context switches:
> 34925294 ± 18% +270.3% 1.293e+08 ± 4%
> will-it-scale.time.voluntary_context_switches
Yang Shi, would you mind taking a look at what's going on?
Linus
