Re: [pipe] 3c0edea9b2: lmbench3.PIPE.bandwidth.MB/sec -17.0% regression

[kernel test robot]

On Mon, Dec 09, 2019 at 10:35:35AM -0800, Linus Torvalds wrote:
> On Mon, Dec 9, 2019 at 12:56 AM Michal Hocko <mhocko@xxxxxxxxxx> wrote:
> >
> > Huh. How can something like that can even can get merged? No changelog,
> > no s-o-b?
> 
> Yeah, I missed that when pulling.
> 
> I wish that had been the only problem we had with that code, but it wasn't.
> 
> Anyway, I'm fairly certain the current git head should fix this
> lmbench3 performance regression too.
> 
>                    Linus

Hi Linus,

Sorry for the inconvenience, indeed, the regression has been fixed.

commit:
  cefa80ced5 ("pipe: Increase the writer-wakeup threshold to reduce context-switch count")
  3c0edea9b2 ("pipe: Remove sync on wake_ups")
  6794862a16 ("Merge tag 'for-5.5-rc1-kconfig-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux")

cefa80ced57a2917  3c0edea9b29f9be6c093f236f7  6794862a16ef41f753abd75c03  testcase/testparams/testbox
----------------  --------------------------  --------------------------  ---------------------------
         %stddev      change         %stddev      change         %stddev
             \          |                \          |                \  
     21204             -17%      17604              23%      26123 Â  3%  lmbench3/performance-development-100%-PIPE-50%-ucode=0x7000019/lkp-bdw-de1
     21204             -17%      17604              23%      26123        GEO-MEAN lmbench3.PIPE.bandwidth.MB/sec

Best Regards,
Rong Chen