On Tue, Jan 28, 2014 at 03:52:47PM -0800, Dave Hansen wrote: > On 01/28/2014 03:29 PM, Andrew Morton wrote: > > On Tue, 28 Jan 2014 15:17:22 -0800 Dave Hansen <d...@sr71.net> wrote: > > This code is borderline insane. > > No argument here. > > > Yes, struct page is special and it's worth spending time and doing > > weird things to optimise it. But sheesh. > > > > An alternative is to make that cmpxchg quietly go away. Is it more > > trouble than it is worth? > > 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
Sure, I've queued tests for the branch. Will report back after 1-2 days. Thanks, Fengguang > 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. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
