Re: [PATCH] mm: slub: fix page->_count corruption (again)

From: David Rientjes
Date: Wed Jan 29 2014 - 03:30:33 EST


On Tue, 28 Jan 2014, Dave Hansen wrote:

> It has measurable performance benefits, and the benefits go up as the
> cost of en/disabling interrupts goes up (like if it takes you a hypercall).
>
> Fengguang, could you run a set of tests for the top patch in this branch
> to see if we'd be giving much up by axing the code?
>
> https://github.com/hansendc/linux/tree/slub-nocmpxchg-for-Fengguang-20140128
>
> I was talking with one of the distros about turning it off as well.
> They mentioned that they saw a few performance regressions when it was
> turned off. I'll share details when I get them.
>

FWIW, I've compared netperf TCP_RR on all machine types I have available
with and without cmpxchg_double and I've never measured a regression.
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