On 4/25/22 16:28, yukuai (C) wrote: > 在 2022/04/25 15:06, Damien Le Moal 写道: > >>>> By the way, did you check that doing something like: >>>> >>>> echo 2048 > /sys/block/sdX/queue/nr_requests >>>> >>>> improves performance for your high number of jobs test case ? >>> >>> Yes, performance will not degrade when numjobs is not greater than 256 >>> in this case. >> >> That is my thinking as well. I am asking if did check that (did you run it ?). > > Hi, > > I'm sure I ran it with 256 jobs before. > > However, I didn't run it with 512 jobs. And following is the result I > just tested: What was nr_requests ? The default 64 ? If you increase that number, do you see better throughput/more requests being sequential ? > > ratio of sequential io: 49.1% > > Read|Write seek > > cnt 99338, zero cnt 48753 > > >=(KB) .. <(KB) : count ratio |distribution > | > 0 .. 1 : 48753 49.1% > |########################################| > 1 .. 2 : 0 0.0% | > | > 2 .. 4 : 0 0.0% | > | > 4 .. 8 : 0 0.0% | > | > 8 .. 16 : 0 0.0% | > | > 16 .. 32 : 0 0.0% | > | > 32 .. 64 : 0 0.0% | > | > 64 .. 128 : 4975 5.0% |##### > | > 128 .. 256 : 4439 4.5% |#### > | > 256 .. 512 : 2615 2.6% |### > | > 512 .. 1024 : 967 1.0% |# > | > 1024 .. 2048 : 213 0.2% |# > | > 2048 .. 4096 : 375 0.4% |# > | > 4096 .. 8192 : 723 0.7% |# > | > 8192 .. 16384 : 1436 1.4% |## > | > 16384 .. 32768 : 2626 2.6% |### > | > 32768 .. 65536 : 4197 4.2% |#### > | > 65536 .. 131072 : 6431 6.5% |###### > | > 131072 .. 262144 : 7590 7.6% |####### > | > 262144 .. 524288 : 6433 6.5% |###### > | > 524288 .. 1048576 : 4583 4.6% |#### > | > 1048576 .. 2097152 : 2237 2.3% |## > | > 2097152 .. 4194304 : 489 0.5% |# > | > 4194304 .. 8388608 : 83 0.1% |# > | > 8388608 .. 16777216 : 36 0.0% |# > | > 16777216 .. 33554432 : 0 0.0% | > | > 33554432 .. 67108864 : 0 0.0% | > | > 67108864 .. 134217728 : 137 0.1% |# > | -- Damien Le Moal Western Digital Research
