Re: [PATCH v6 4/5] MCS Lock: Barrier corrections

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Fri, Nov 29, 2013 at 04:44:41PM +0000, Linus Torvalds wrote:
> 
> On Nov 29, 2013 8:18 AM, "Will Deacon"
> <will.deacon@xxxxxxx<mailto:will.deacon@xxxxxxx>> wrote:
> >
> >  To get some sort of idea, I tried adding a dmb to the start of
> >  spin_unlock on ARMv7 and I saw a 3% performance hit in hackbench on my
> >  dual-cluster board.
> 
> Don't do a dmb. Just do a dummy release. You just said that on arm64 a
> unlock+lock is a memory barrier, so just make the mb__before_spinlock() be
> a dummy store with release to the stack..

Good idea! That should work quite nicely (I don't have anything sane I can
benchmark it on), so I think that solves the issue I was moaning about.

Will

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>




[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [IETF Annouce]     [Bugtraq]     [Linux]     [Linux OMAP]     [Linux MIPS]     [ECOS]     [Asterisk Internet PBX]     [Linux API]