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Re: [RFC 0/3] block/file-posix: Work around XFS bug
From: |
Max Reitz |
Subject: |
Re: [RFC 0/3] block/file-posix: Work around XFS bug |
Date: |
Mon, 4 Nov 2019 17:07:23 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 |
On 04.11.19 16:49, Alberto Garcia wrote:
> On Mon 04 Nov 2019 04:14:56 PM CET, Max Reitz wrote:
>
>>>> No, what I meant was that the original problem that led to
>>>> c8bb23cbdbe would go away.
>>>
>>> Ah, right. Not quite, according to my numbers:
>>>
>>> |--------------+----------------+-----------------+-------------|
>>> | Cluster size | subclusters=on | subclusters=off | fallocate() |
>>> |--------------+----------------+-----------------+-------------|
>>> | 256 KB | 10182 IOPS | 966 IOPS | 14007 IOPS |
>>> | 512 KB | 7919 IOPS | 563 IOPS | 13442 IOPS |
>>> | 1024 KB | 5050 IOPS | 465 IOPS | 13887 IOPS |
>>> | 2048 KB | 2465 IOPS | 271 IOPS | 13885 IOPS |
>>> |--------------+----------------+-----------------+-------------|
>>>
>>> There's obviously no backing image, and only the last column uses
>>> handle_alloc_space() / fallocate().
>>
>> Thanks for providing some numbers!
>>
>> It was my impression, too, that subclusters wouldn’t solve it. But it
>> didn’t seem like that big of a difference to me. Did you run this
>> with aio=native? (Because that’s where we have the XFS problem)
>
> Here's with aio=native
>
> |--------------+----------------+-----------------+-------------|
> | Cluster size | subclusters=on | subclusters=off | fallocate() |
> |--------------+----------------+-----------------+-------------|
> | 256 KB | 19897 IOPS | 891 IOPS | 32194 IOPS |
> | 512 KB | 17881 IOPS | 436 IOPS | 33092 IOPS |
> | 1024 KB | 17050 IOPS | 341 IOPS | 32768 IOPS |
> | 2048 KB | 7854 IOPS | 207 IOPS | 30944 IOPS |
> |--------------+----------------+-----------------+-------------|
OK, thanks again. :-)
So it seems right not to revert the commit and just work around the XFS
bug in file-posix.
Max
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