Messages in this thread | | | From | Andi Kleen <> | Subject | Re: [GIT PULL] Lockless SLUB slowpaths for v3.1-rc1 | Date | Sun, 31 Jul 2011 10:39:58 -0700 |
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Linus Torvalds <torvalds@linux-foundation.org> writes:
> On Sat, Jul 30, 2011 at 8:27 AM, Linus Torvalds > <torvalds@linux-foundation.org> wrote: >> >> Do we allocate the page map array sufficiently aligned that we >> actually don't ever have the case of straddling a cacheline? I didn't >> check. > > Oh, and another thing worth checking: did somebody actually check the > timings for:
I would like to see a followon patch that moves the mem_cgroup pointer back into struct page. Copying some mem_cgroup people.
> > - *just* the alignment change? > > IOW, maybe some of the netperf improvement isn't from the lockless > path, but exactly from 'struct page' always being in a single > cacheline? > > - check performance with cmpxchg16b *without* the alignment. > > Sometimes especially intel is so good at unaligned accesses that > you wouldn't see an issue. Now, locked ops are usually special (and
As Eric pointed out CMPXCHG16B requires alignment, it #GPs otherwise.
-Andi -- ak@linux.intel.com -- Speaking for myself only
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