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Message-ID: <adae6bff-8401-b641-438c-d212b20a7430@huaweicloud.com>
Date: Wed, 13 Nov 2024 09:18:14 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: Dragan Milivojević <galileo@...-inc.com>,
Yu Kuai <yukuai1@...weicloud.com>, "yukuai (C)" <yukuai3@...wei.com>
Cc: Song Liu <song@...nel.org>, linux-raid@...r.kernel.org,
linux-kernel@...r.kernel.org, yi.zhang@...wei.com, yangerkun@...wei.com,
"Luse, Paul E" <paul.e.luse@...el.com>
Subject: Re: [PATCH md-6.13] md: remove bitmap file support
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
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