From: Dave Chinner <david@fromorbit.com>
To: Anton Gavriliuk <antosha20xx@gmail.com>
Cc: Laurence Oberman <loberman@redhat.com>,
linux-nvme@lists.infradead.org, linux-xfs@vger.kernel.org,
linux-block@vger.kernel.org
Subject: Re: Sequential read from NVMe/XFS twice slower on Fedora 42 than on Rocky 9.5
Date: Wed, 7 May 2025 07:46:01 +1000 [thread overview]
Message-ID: <aBqDGY1i3RePyzaB@dread.disaster.area> (raw)
In-Reply-To: <CAAiJnjo87CEeFrkHbXtQM-=+K9M8uEpythLthWTwM_-i4HMA_Q@mail.gmail.com>
On Tue, May 06, 2025 at 02:03:37PM +0300, Anton Gavriliuk wrote:
> > So is this MD chunk size related? i.e. what is the chunk size
> > the MD device? Is it smaller than the IO size (256kB) or larger?
> > Does the regression go away if the chunk size matches the IO size,
> > or if the IO size vs chunk size relationship is reversed?
>
> According to the output below, the chunk size is 512K,
Ok.
`iostat -dxm 5` output during the fio run on both kernels will give
us some indication of the differences in IO patterns, queue depths,
etc.
Silly question: if you use DM to create the same RAID 0 array
with a dm table such as:
0 75011629056 striped 12 1024 /dev/nvme7n1 0 /dev/nvme0n1 0 .... /dev/nvme12n1 0
to create a similar 38TB raid 0 array, do you see the same perf
degradation?
-Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2025-05-06 21:46 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-05-03 21:04 Sequential read from NVMe/XFS twice slower on Fedora 42 than on Rocky 9.5 Anton Gavriliuk
2025-05-03 22:16 ` Dave Chinner
2025-05-04 7:22 ` Anton Gavriliuk
2025-05-04 21:50 ` Dave Chinner
2025-05-05 12:29 ` Laurence Oberman
2025-05-05 13:21 ` Laurence Oberman
2025-05-05 17:39 ` Laurence Oberman
2025-05-22 15:07 ` Laurence Oberman
2025-05-23 9:39 ` Anton Gavriliuk
2025-05-05 22:56 ` Dave Chinner
2025-05-06 11:03 ` Anton Gavriliuk
2025-05-06 21:46 ` Dave Chinner [this message]
2025-05-07 12:26 ` Anton Gavriliuk
2025-05-07 21:59 ` Dave Chinner
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