Messages in this thread | | | Date | Wed, 29 Jan 2014 14:43:50 +0800 | From | Fengguang Wu <> | Subject | Re: [PATCH] mm: slub: fix page->_count corruption (again) |
| |
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 <dave@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.
| |