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
