v2:
- Add patch 2 to optimize __down_read_trylock() as suggested by PeterZ.
- Update performance test data in patch 1.
This is part 0 of my rwsem patchset. It just removes the architecture
specific files to make it easer to add enhancements in the upcoming
rwsem patches.
Since the two ll/sc
Modify __down_read_trylock() to make it generate slightly better code
(smaller and maybe a tiny bit faster).
Before this patch, down_read_trylock:
0x <+0>: callq 0x5
0x0005 <+5>: jmp0x18
0x0007 <+7>: lea0x1(%rdx),%rcx
As the generic rwsem-xadd code is using the appropriate acquire and
release versions of the atomic operations, the arch specific rwsem.h
files will not be that much faster than the generic code as long as the
atomic functions are properly implemented. So we can remove those arch
specific rwsem.h
The pull request you sent on Sun, 10 Feb 2019 20:46:15 -0800:
> git://git.kernel.org/pub/scm/linux/kernel/git/mattst88/alpha.git for-linus
has been merged into torvalds/linux.git:
https://git.kernel.org/torvalds/c/244cce14c17705e6376cd12c20c27f8712793acc
Thank you!
--
Deet-doot-dot, I am a
On Mon, Feb 11, 2019 at 11:35:24AM -0500, Waiman Long wrote:
> On 02/11/2019 06:58 AM, Peter Zijlstra wrote:
> > Which is clearly worse. Now we can write that as:
> >
> > int __down_read_trylock2(unsigned long *l)
> > {
> > long tmp = READ_ONCE(*l);
> >
> > while (tmp >= 0) {
> >
On 02/11/2019 06:58 AM, Peter Zijlstra wrote:
> Which is clearly worse. Now we can write that as:
>
> int __down_read_trylock2(unsigned long *l)
> {
> long tmp = READ_ONCE(*l);
>
> while (tmp >= 0) {
> if (try_cmpxchg(l, , tmp + 1))
>
On Sun, Feb 10, 2019 at 09:00:50PM -0500, Waiman Long wrote:
> +static inline int __down_read_trylock(struct rw_semaphore *sem)
> +{
> + long tmp;
> +
> + while ((tmp = atomic_long_read(>count)) >= 0) {
> + if (tmp == atomic_long_cmpxchg_acquire(>count, tmp,
> +
On Mon, Feb 11, 2019 at 10:40:44AM +0100, Peter Zijlstra wrote:
> On Mon, Feb 11, 2019 at 10:36:01AM +0100, Peter Zijlstra wrote:
> > On Sun, Feb 10, 2019 at 09:00:50PM -0500, Waiman Long wrote:
> > > +static inline int __down_read_trylock(struct rw_semaphore *sem)
> > > +{
> > > + long tmp;
> > >
* Will Deacon wrote:
> On Mon, Feb 11, 2019 at 11:39:27AM +0100, Ingo Molnar wrote:
> >
> > * Ingo Molnar wrote:
> >
> > > Sounds good to me - I've merged this patch, will push it out after
> > > testing.
> >
> > Based on Peter's feedback I'm delaying this - performance testing on at
> >
On Mon, Feb 11, 2019 at 11:39:27AM +0100, Ingo Molnar wrote:
>
> * Ingo Molnar wrote:
>
> > Sounds good to me - I've merged this patch, will push it out after
> > testing.
>
> Based on Peter's feedback I'm delaying this - performance testing on at
> least one key ll/sc arch would be nice
* Ingo Molnar wrote:
> Sounds good to me - I've merged this patch, will push it out after
> testing.
Based on Peter's feedback I'm delaying this - performance testing on at
least one key ll/sc arch would be nice indeed.
Thanks,
Ingo
On Mon, Feb 11, 2019 at 10:36:01AM +0100, Peter Zijlstra wrote:
> On Sun, Feb 10, 2019 at 09:00:50PM -0500, Waiman Long wrote:
> > +static inline int __down_read_trylock(struct rw_semaphore *sem)
> > +{
> > + long tmp;
> > +
> > + while ((tmp = atomic_long_read(>count)) >= 0) {
> > +
On Sun, Feb 10, 2019 at 09:00:50PM -0500, Waiman Long wrote:
> diff --git a/kernel/locking/rwsem.h b/kernel/locking/rwsem.h
> index bad2bca..067e265 100644
> --- a/kernel/locking/rwsem.h
> +++ b/kernel/locking/rwsem.h
> @@ -32,6 +32,26 @@
> # define DEBUG_RWSEMS_WARN_ON(c)
> #endif
>
> +/*
> +
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