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Message-ID: <20150616105732.2bc37714@redhat.com> Date: Tue, 16 Jun 2015 10:57:32 +0200 From: Jesper Dangaard Brouer <brouer@...hat.com> To: Joonsoo Kim <iamjoonsoo.kim@....com> Cc: linux-mm@...ck.org, Christoph Lameter <cl@...ux.com>, Andrew Morton <akpm@...ux-foundation.org>, netdev@...r.kernel.org, Alexander Duyck <alexander.duyck@...il.com>, brouer@...hat.com Subject: Re: [PATCH 7/7] slub: initial bulk free implementation On Tue, 16 Jun 2015 10:21:10 +0200 Jesper Dangaard Brouer <brouer@...hat.com> wrote: > > On Tue, 16 Jun 2015 16:28:06 +0900 Joonsoo Kim <iamjoonsoo.kim@....com> wrote: > > > Is this really better than just calling __kmem_cache_free_bulk()? > > Yes, as can be seen by cover-letter, but my cover-letter does not seem > to have reached mm-list. > > Measurements for the entire patchset: > > Bulk - Fallback bulking - fastpath-bulking > 1 - 47 cycles(tsc) 11.921 ns - 45 cycles(tsc) 11.461 ns improved 4.3% > 2 - 46 cycles(tsc) 11.649 ns - 28 cycles(tsc) 7.023 ns improved 39.1% > 3 - 46 cycles(tsc) 11.550 ns - 22 cycles(tsc) 5.671 ns improved 52.2% > 4 - 45 cycles(tsc) 11.398 ns - 19 cycles(tsc) 4.967 ns improved 57.8% > 8 - 45 cycles(tsc) 11.303 ns - 17 cycles(tsc) 4.298 ns improved 62.2% > 16 - 44 cycles(tsc) 11.221 ns - 17 cycles(tsc) 4.423 ns improved 61.4% > 30 - 75 cycles(tsc) 18.894 ns - 57 cycles(tsc) 14.497 ns improved 24.0% > 32 - 73 cycles(tsc) 18.491 ns - 56 cycles(tsc) 14.227 ns improved 23.3% > 34 - 75 cycles(tsc) 18.962 ns - 58 cycles(tsc) 14.638 ns improved 22.7% > 48 - 80 cycles(tsc) 20.049 ns - 64 cycles(tsc) 16.247 ns improved 20.0% > 64 - 87 cycles(tsc) 21.929 ns - 74 cycles(tsc) 18.598 ns improved 14.9% > 128 - 98 cycles(tsc) 24.511 ns - 89 cycles(tsc) 22.295 ns improved 9.2% > 158 - 101 cycles(tsc) 25.389 ns - 93 cycles(tsc) 23.390 ns improved 7.9% > 250 - 104 cycles(tsc) 26.170 ns - 100 cycles(tsc) 25.112 ns improved 3.8% > > I'll do a compare against the previous patch, and post the results. Compare against previous patch: Run: previous-patch - this patch 1 - 49 cycles(tsc) 12.378 ns - 43 cycles(tsc) 10.775 ns improved 12.2% 2 - 37 cycles(tsc) 9.297 ns - 26 cycles(tsc) 6.652 ns improved 29.7% 3 - 33 cycles(tsc) 8.348 ns - 21 cycles(tsc) 5.347 ns improved 36.4% 4 - 31 cycles(tsc) 7.930 ns - 18 cycles(tsc) 4.669 ns improved 41.9% 8 - 30 cycles(tsc) 7.693 ns - 17 cycles(tsc) 4.404 ns improved 43.3% 16 - 32 cycles(tsc) 8.059 ns - 17 cycles(tsc) 4.493 ns improved 46.9% 30 - 65 cycles(tsc) 16.345 ns - 59 cycles(tsc) 14.858 ns improved 9.2% 32 - 64 cycles(tsc) 16.170 ns - 56 cycles(tsc) 14.074 ns improved 12.5% 34 - 66 cycles(tsc) 16.645 ns - 55 cycles(tsc) 13.882 ns improved 16.7% 48 - 78 cycles(tsc) 19.581 ns - 65 cycles(tsc) 16.266 ns improved 16.7% 64 - 81 cycles(tsc) 20.428 ns - 77 cycles(tsc) 19.432 ns improved 4.9% 128 - 92 cycles(tsc) 23.030 ns - 78 cycles(tsc) 19.650 ns improved 15.2% 158 - 94 cycles(tsc) 23.581 ns - 83 cycles(tsc) 20.953 ns improved 11.7% 250 - 96 cycles(tsc) 24.175 ns - 93 cycles(tsc) 23.444 ns improved 3.1% This mostly amortize the less-heavy none-locked cmpxchg_double used on fastpath. As I demonstrated earlier this fastpath cmpxchg is approx 38% of the fastpath cost. Thus, yes, doing bulk free this way is faster ;-) -- Best regards, Jesper Dangaard Brouer MSc.CS, Sr. Network Kernel Developer at Red Hat Author of http://www.iptv-analyzer.org LinkedIn: http://www.linkedin.com/in/brouer -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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