在 2022/04/25 19:20, Damien Le Moal 写道:
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 ?
Sorry if I didn't explain this clearly.
If nr_requests is 64, numjobs is 512, the ratio of sequential is about
20%. If nr_requests is 2048, numjobs is 512, the ratio is 49.1%.
Then yes, increase nr_requests can improve performance in the test case.
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% |#
|
