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Date: Thu, 04 Sep 2014 15:53:46 -0700 From: Dave Hansen <dave.hansen@...el.com> To: Dave Hansen <dave@...1.net>, Michal Hocko <mhocko@...e.cz> CC: Johannes Weiner <hannes@...xchg.org>, Hugh Dickins <hughd@...gle.com>, Tejun Heo <tj@...nel.org>, Linux-MM <linux-mm@...ck.org>, Andrew Morton <akpm@...ux-foundation.org>, Linus Torvalds <torvalds@...ux-foundation.org>, Vladimir Davydov <vdavydov@...allels.com>, LKML <linux-kernel@...r.kernel.org> Subject: Re: regression caused by cgroups optimization in 3.17-rc2 On 09/04/2014 01:27 PM, Dave Hansen wrote: > On 09/04/2014 07:27 AM, Michal Hocko wrote: >> Ouch. free_pages_and_swap_cache completely kills the uncharge batching >> because it reduces it to PAGEVEC_SIZE batches. >> >> I think we really do not need PAGEVEC_SIZE batching anymore. We are >> already batching on tlb_gather layer. That one is limited so I think >> the below should be safe but I have to think about this some more. There >> is a risk of prolonged lru_lock wait times but the number of pages is >> limited to 10k and the heavy work is done outside of the lock. If this >> is really a problem then we can tear LRU part and the actual >> freeing/uncharging into a separate functions in this path. >> >> Could you test with this half baked patch, please? I didn't get to test >> it myself unfortunately. > > 3.16 settled out at about 11.5M faults/sec before the regression. This > patch gets it back up to about 10.5M, which is good. The top spinlock > contention in the kernel is still from the resource counter code via > mem_cgroup_commit_charge(), though. > > I'm running Johannes' patch now. This looks pretty good. The area where it plateaus (above 80 threads where hyperthreading kicks in) might be a bit slower than it was in 3.16, but that could easily be from other things. > https://www.sr71.net/~dave/intel/bb.html?1=3.16.0-rc4-g67b9d76/&2=3.17.0-rc3-g57b252f Feel free to add my Tested-by: -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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