Messages in this thread | | | Date | Tue, 19 Nov 2013 13:27:22 -0700 | From | Khalid Aziz <> | Subject | Re: [PATCH 0/3] mm: hugetlbfs: fix hugetlbfs optimization v2 |
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On 11/18/2013 11:04 AM, Khalid Aziz wrote: > 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
Hi Andrea,
I found that a background task running on my test server had influenced the performance numbers for 1M reads. I cleaned that problem up and re-ran the test. I am seeing 8456 MB/sec with all three patches applied, so 1M number is looking good as well.
-- Khalid
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