Messages in this thread |  | | Date | Mon, 18 Nov 2013 11:04:23 -0700 | From | Khalid Aziz <> | Subject | Re: [PATCH 0/3] mm: hugetlbfs: fix hugetlbfs optimization v2 |
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On 11/15/2013 10:47 AM, Andrea Arcangeli wrote: > Hi, > > 1/3 is a bugfix so it should be applied more urgently. 1/3 is not as > fast as the current upstream code in the hugetlbfs + directio extreme > 8GB/sec benchmark (but 3/3 should fill the gap later). The code is > identical to the one I posted in v1 just rebased on upstream and was > developed in collaboration with Khalid who already tested it. > > 2/3 and 3/3 had very little testing yet, and they're incremental > optimization. 2/3 is minor and most certainly worth applying later. > > 3/3 instead complicates things a bit and adds more branches to the THP > fast paths, so it should only be applied if the benchmarks of > hugetlbfs + directio show that it is very worthwhile (that has not > been verified yet). If it's not worthwhile 3/3 should be dropped (and > the gap should be filled in some other way if the gap is not caused by > the _mapcount mangling as I guessed). Ideally this should bring even > more performance than current upstream code, as current upstream code > still increased the _mapcount in gup_fast by mistake, while this > eliminates the locked op on the tail page cacheline in gup_fast too > (which is required for correctness too).
Hi Andrea,
I ran directio benchmark and here are the performance numbers (MBytes/sec):
Block size 3.12 3.12+patch 1 3.12+patch 1,2,3 ---------- ---- ------------ ---------------- 1M 8467 8114 7648 64K 4049 4043 4175
Performance numbers with 64K reads look good but there is further deterioration with 1M reads.
-- Khalid
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