lkml.org 
[lkml]   [2017]   [Apr]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC PATCH 0/3] arm64: queued spinlocks and rw-locks
On Thu, Apr 13, 2017 at 01:33:09PM +0300, Yury Norov wrote:
> On Wed, Apr 12, 2017 at 01:04:55PM -0400, Adam Wallis wrote:
> > On 4/10/2017 5:35 PM, Yury Norov wrote:
> > > The patch of Jan Glauber enables queued spinlocks on arm64. I rebased it on
> > > latest kernel sources, and added a couple of fixes to headers to apply it
> > > smoothly.
> > >
> > > Though, locktourture test shows significant performance degradation in the
> > > acquisition of rw-lock for read on qemu:
> > >
> > > Before After
> > > spin_lock-torture: 38957034 37076367 -4.83
> > > rw_lock-torture W: 5369471 18971957 253.33
> > > rw_lock-torture R: 6413179 3668160 -42.80
> > >
> >
> > On our 48 core QDF2400 part, I am seeing huge improvements with these patches on
> > the torture tests. The improvements go up even further when I apply Jason Low's
> > MCS Spinlock patch: https://lkml.org/lkml/2016/4/20/725
>
> It sounds great. So performance issue is looking like my local
> problem, most probably because I ran tests on Qemu VM.
>
> I don't see any problems with this series, other than performance,
> and if it looks fine now, I think it's good enough for upstream.

I would still like to understand why you see such a significant performance
degradation, and whether or not you also see that on native hardware (i.e.
without Qemu involved).

Will

\
 
 \ /
  Last update: 2017-04-28 17:38    [W:0.075 / U:1.012 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site