Re: [PATCH 0/5 v2] locks: avoid thundering-herd wake-ups

2018-08-14 Thread Jeff Layton
On Tue, 2018-08-14 at 14:41 -0400, J. Bruce Fields wrote: > This version looks correct to me, and simpler. I'll be curious to hear > whatever you learn from testing! > > --b. > Agreed. I'll go ahead and put this in linux-next with an eye toward merging in v4.20 if we don't hit any major problem

Re: [PATCH 0/5 v2] locks: avoid thundering-herd wake-ups

2018-08-14 Thread J. Bruce Fields
This version looks correct to me, and simpler. I'll be curious to hear whatever you learn from testing! --b. On Tue, Aug 14, 2018 at 01:56:51PM +1000, NeilBrown wrote: > > V2, which added wake_non_conflicts() was more broken than V1 - as > Bruce explained there is no transitivity in the blockin

Re: [PATCH 0/5 - V2] locks: avoid thundering-herd wake-ups

2018-08-11 Thread Jeff Layton
On Sat, 2018-08-11 at 08:21 -0400, J. Bruce Fields wrote: > On Sat, Aug 11, 2018 at 07:51:13AM -0400, Jeff Layton wrote: > > On Thu, 2018-08-09 at 20:29 -0400, J. Bruce Fields wrote: > > > On Fri, Aug 10, 2018 at 08:12:43AM +1000, NeilBrown wrote: > > > > On Thu, Aug 09 2018, J. Bruce Fields wrote:

Re: [PATCH 0/5 - V2] locks: avoid thundering-herd wake-ups

2018-08-11 Thread J. Bruce Fields
On Sat, Aug 11, 2018 at 07:56:25AM -0400, Jeff Layton wrote: > FWIW, I did a bit of testing with lockperf tests that I had written on > an earlier rework of this code: > > https://git.samba.org/jlayton/linux.git/?p=jlayton/lockperf.git;a=summary > > > The posix01 and flock01 tests in there s

Re: [PATCH 0/5 - V2] locks: avoid thundering-herd wake-ups

2018-08-11 Thread J. Bruce Fields
On Sat, Aug 11, 2018 at 07:51:13AM -0400, Jeff Layton wrote: > On Thu, 2018-08-09 at 20:29 -0400, J. Bruce Fields wrote: > > On Fri, Aug 10, 2018 at 08:12:43AM +1000, NeilBrown wrote: > > > On Thu, Aug 09 2018, J. Bruce Fields wrote: > > > > > > > I think there's also a problem with multiple tasks

Re: [PATCH 0/5 - V2] locks: avoid thundering-herd wake-ups

2018-08-11 Thread Jeff Layton
On Fri, 2018-08-10 at 11:47 -0400, J. Bruce Fields wrote: > On Fri, Aug 10, 2018 at 01:17:14PM +1000, NeilBrown wrote: > > On Thu, Aug 09 2018, J. Bruce Fields wrote: > > > > > On Fri, Aug 10, 2018 at 11:50:58AM +1000, NeilBrown wrote: > > > > You're good at this game! > > > > > > Everybody's got

Re: [PATCH 0/5 - V2] locks: avoid thundering-herd wake-ups

2018-08-11 Thread Jeff Layton
On Thu, 2018-08-09 at 20:29 -0400, J. Bruce Fields wrote: > On Fri, Aug 10, 2018 at 08:12:43AM +1000, NeilBrown wrote: > > On Thu, Aug 09 2018, J. Bruce Fields wrote: > > > > > I think there's also a problem with multiple tasks sharing the same > > > lock owner. > > > > > > So, all locks are excl

Re: [PATCH 0/5 - V2] locks: avoid thundering-herd wake-ups

2018-08-10 Thread J. Bruce Fields
On Fri, Aug 10, 2018 at 01:17:14PM +1000, NeilBrown wrote: > On Thu, Aug 09 2018, J. Bruce Fields wrote: > > > On Fri, Aug 10, 2018 at 11:50:58AM +1000, NeilBrown wrote: > >> You're good at this game! > > > > Everybody's got to have a hobby, mine is pathological posix locking > > cases > > > >

Re: [PATCH 0/5 - V2] locks: avoid thundering-herd wake-ups

2018-08-09 Thread NeilBrown
On Thu, Aug 09 2018, J. Bruce Fields wrote: > On Fri, Aug 10, 2018 at 11:50:58AM +1000, NeilBrown wrote: >> You're good at this game! > > Everybody's got to have a hobby, mine is pathological posix locking > cases > >> So, because a locker with the same "owner" gets a free pass, you can >> *ne

Re: [PATCH 0/5 - V2] locks: avoid thundering-herd wake-ups

2018-08-09 Thread J. Bruce Fields
On Fri, Aug 10, 2018 at 11:50:58AM +1000, NeilBrown wrote: > You're good at this game! Everybody's got to have a hobby, mine is pathological posix locking cases > So, because a locker with the same "owner" gets a free pass, you can > *never* say that any lock which conflicts with A also confl

Re: [PATCH 0/5 - V2] locks: avoid thundering-herd wake-ups

2018-08-09 Thread NeilBrown
On Thu, Aug 09 2018, J. Bruce Fields wrote: > On Fri, Aug 10, 2018 at 08:12:43AM +1000, NeilBrown wrote: >> On Thu, Aug 09 2018, J. Bruce Fields wrote: >> >> > I think there's also a problem with multiple tasks sharing the same >> > lock owner. >> > >> > So, all locks are exclusive locks for the

Re: [PATCH 0/5 - V2] locks: avoid thundering-herd wake-ups

2018-08-09 Thread J. Bruce Fields
On Fri, Aug 10, 2018 at 08:12:43AM +1000, NeilBrown wrote: > On Thu, Aug 09 2018, J. Bruce Fields wrote: > > > I think there's also a problem with multiple tasks sharing the same > > lock owner. > > > > So, all locks are exclusive locks for the same range. We have four > > tasks. Tasks 1 and 4 s

Re: [PATCH 0/5 - V2] locks: avoid thundering-herd wake-ups

2018-08-09 Thread NeilBrown
On Thu, Aug 09 2018, J. Bruce Fields wrote: > I think there's also a problem with multiple tasks sharing the same > lock owner. > > So, all locks are exclusive locks for the same range. We have four > tasks. Tasks 1 and 4 share the same owner, the others' owners are > distinct. > > - Task

Re: [PATCH 0/5 - V2] locks: avoid thundering-herd wake-ups

2018-08-09 Thread J. Bruce Fields
I think there's also a problem with multiple tasks sharing the same lock owner. So, all locks are exclusive locks for the same range. We have four tasks. Tasks 1 and 4 share the same owner, the others' owners are distinct. - Task 1 gets a lock. - Task 2 gets a conflicting lock.