Re: [PATCH 0/7] Add rcu_sync infrastructure to avoid _expedited() in percpu-rwsem

2015-07-17 Thread Paul E. McKenney
On Sat, Jul 18, 2015 at 01:29:30AM +0200, Oleg Nesterov wrote: > On 07/15, Paul E. McKenney wrote: > > > > On Wed, Jul 15, 2015 at 09:36:01PM +0200, Oleg Nesterov wrote: > > > > > > Do you mean you need another user except percpu_rw_semaphore? I do > > > not see any right now... > > > > Not asking

Re: [PATCH 0/7] Add rcu_sync infrastructure to avoid _expedited() in percpu-rwsem

2015-07-17 Thread Oleg Nesterov
On 07/15, Paul E. McKenney wrote: > > On Wed, Jul 15, 2015 at 09:36:01PM +0200, Oleg Nesterov wrote: > > > > Do you mean you need another user except percpu_rw_semaphore? I do > > not see any right now... > > Not asking for more than one use, but it does need a use. I believe > that percpu_rw_sema

Re: [PATCH 0/7] Add rcu_sync infrastructure to avoid _expedited() in percpu-rwsem

2015-07-15 Thread Paul E. McKenney
On Wed, Jul 15, 2015 at 09:36:01PM +0200, Oleg Nesterov wrote: > On 07/15, Paul E. McKenney wrote: > > > > On Sun, Jul 12, 2015 at 01:35:35AM +0200, Oleg Nesterov wrote: > > > > > Let's start with the simple test-case, > > > > > > #!/bin/bash > > > > > > perf probe -x /lib/libc.so.6 syscall > >

Re: [PATCH 0/7] Add rcu_sync infrastructure to avoid _expedited() in percpu-rwsem

2015-07-15 Thread Oleg Nesterov
On 07/15, Paul E. McKenney wrote: > > On Sun, Jul 12, 2015 at 01:35:35AM +0200, Oleg Nesterov wrote: > > > Let's start with the simple test-case, > > > > #!/bin/bash > > > > perf probe -x /lib/libc.so.6 syscall > > > > for i in {1..1000}; do > > echo 1 >| > > /sys/kernel/de

Re: [PATCH 0/7] Add rcu_sync infrastructure to avoid _expedited() in percpu-rwsem

2015-07-15 Thread Paul E. McKenney
On Sun, Jul 12, 2015 at 01:35:35AM +0200, Oleg Nesterov wrote: > Hello, > > Let me make another attempt to push rcu_sync and add a _simple_ > improvment into percpu-rwsem. It already has another user (cgroups) > and I think it can have more. Peter has some use-cases. sb->s_writers > (which afaics

Re: [PATCH 0/7] Add rcu_sync infrastructure to avoid _expedited() in percpu-rwsem

2015-07-11 Thread Linus Torvalds
On Sat, Jul 11, 2015 at 4:35 PM, Oleg Nesterov wrote: > > Linus, I am mostly trying to convince you. Nobody else objected so far. > Could you please comment? I don't mind this part of the series. It's the whole "do we really want to put the effort into percpu-rwsem I worry about, as there just a

[PATCH 0/7] Add rcu_sync infrastructure to avoid _expedited() in percpu-rwsem

2015-07-11 Thread Oleg Nesterov
Hello, Let me make another attempt to push rcu_sync and add a _simple_ improvment into percpu-rwsem. It already has another user (cgroups) and I think it can have more. Peter has some use-cases. sb->s_writers (which afaics is buggy btw) can be turned into percpu-rwsem too I think. Linus, I am mos