Hi,
在 2024/11/11 22:07, Dragan Milivojević 写道:
Reads are fine but writes are many times slower ...
I still can't believe your test result, and I can't figure out why
internal bitmap is so slow. Hence I use ramdisk(10GB) to create a raid5,
and use the same fio script to test, the result is quite different from
yours:
ram0: 981MiB/s
non-bitmap: 132MiB/s
internal-bitmap: 95.5MiB/s
So, I waited for Paul to have a chance to give it a test for real disks,
still, results are similar to above.
I don't know, I can provide full fio test logs including fio "tracing"
for these iodepth 8
tests if that would make any difference.
No, I don't need fio logs.
There is absolutely something wrong here, it doesn't make sense to me
that internal bitmap is so slow. However, I have no idea until you can
provide the perf result.
I may be able to find time to do that over the weekend, but don’t hold
me to it.
The test setup will not be the same, server is in production ...
I did leave some "spare" partitions on all drives to investigate this
issue further
but did not find the time.
Please send me an example of how would you like me to run the perf tool,
I haven't used
it much.
You can see examples here:
https://github.com/brendangregg/FlameGraph
To be short, while test is running:
perf record -a -g -- sleep 10
perf script -i perf.data | ./stackcollapse-perf.pl | ./flamegraph.pl
BTW, you said that you're using production environment, this will
probably make it hard to analyze performance.
Thanks,
Kuai
