| Message ID | 1507208097-825-1-git-send-email-will.deacon@arm.com |
|---|---|
| Headers | show |
| Series | Switch arm64 over to qrwlock | expand |
Hi, On 10/05/2017 07:54 AM, Will Deacon wrote: > Hi all, > > This patch series reworks bits of the qrwlock code that it can be used > to replace the asm rwlocks currently implemented for arm64. The structure > of the series is: > > Patches 1-3 : Work WFE into qrwlock using atomic_cond_read_acquire so > we can avoid busy-waiting. > > Patch 4 : Enable qrwlocks for arm64 > > Patch 5-6 : Ensure writer slowpath fairness. This has a potential > performance impact on the writer unlock path, so I've > kept them at the end. > > The patches apply on top of my other locking cleanups: > > http://lkml.kernel.org/r/1507055129-12300-1-git-send-email-will.deacon@arm.com > > although the conflict with mainline is trivial to resolve without those. > The full stack is also pushed here: > > git://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git qrwlock > > All comments (particularly related to testing and performance) welcome! I haven't done any perf testing, but the machines continue to boot, and the stress-ng test which causes task lock problems with the normal arm64 rwlock now appears to run as expected. So, its a good start! > > Cheers, > > Will > > --->8 > > Will Deacon (6): > kernel/locking: Use struct qrwlock instead of struct __qrwlock > locking/atomic: Add atomic_cond_read_acquire > kernel/locking: Use atomic_cond_read_acquire when spinning in qrwlock > arm64: locking: Move rwlock implementation over to qrwlocks > kernel/locking: Prevent slowpath writers getting held up by fastpath > kernel/locking: Remove unused union members from struct qrwlock > > arch/arm64/Kconfig | 17 ++++ > arch/arm64/include/asm/Kbuild | 1 + > arch/arm64/include/asm/spinlock.h | 164 +------------------------------- > arch/arm64/include/asm/spinlock_types.h | 6 +- > include/asm-generic/atomic-long.h | 3 + > include/asm-generic/qrwlock.h | 14 +-- > include/asm-generic/qrwlock_types.h | 2 +- > include/linux/atomic.h | 4 + > kernel/locking/qrwlock.c | 83 +++------------- > 9 files changed, 43 insertions(+), 251 deletions(-) >
Hi Jeremy, On Thu, Oct 05, 2017 at 05:12:44PM -0500, Jeremy Linton wrote: > On 10/05/2017 07:54 AM, Will Deacon wrote: > >This patch series reworks bits of the qrwlock code that it can be used > >to replace the asm rwlocks currently implemented for arm64. The structure > >of the series is: > > > > Patches 1-3 : Work WFE into qrwlock using atomic_cond_read_acquire so > > we can avoid busy-waiting. > > > > Patch 4 : Enable qrwlocks for arm64 > > > > Patch 5-6 : Ensure writer slowpath fairness. This has a potential > > performance impact on the writer unlock path, so I've > > kept them at the end. > > > >The patches apply on top of my other locking cleanups: > > > > http://lkml.kernel.org/r/1507055129-12300-1-git-send-email-will.deacon@arm.com > > > >although the conflict with mainline is trivial to resolve without those. > >The full stack is also pushed here: > > > > git://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git qrwlock > > > >All comments (particularly related to testing and performance) welcome! > > I haven't done any perf testing, but the machines continue to boot, and the > stress-ng test which causes task lock problems with the normal arm64 rwlock > now appears to run as expected. So, its a good start! Excellent! Mind if I add your tested-by? Will