From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: Chaitanya Kulkarni <chaitanyak@nvidia.com>,
Saeed Mirzamohammadi <saeed.mirzamohammadi@oracle.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
Ramanan Govindarajan <ramanan.govindarajan@oracle.com>,
Sagi Grimberg <sagi@grimberg.me>,
Paul Webb <paul.x.webb@oracle.com>,
Christoph Hellwig <hch@lst.de>, Keith Busch <kbusch@kernel.org>
Subject: Re: [bug-report] 5-9% FIO randomwrite ext4 perf regression on 6.12.y kernel
Date: Thu, 21 Nov 2024 05:57:14 +0100 [thread overview]
Message-ID: <20241121045714.GA20680@lst.de> (raw)
In-Reply-To: <d6049cd0-5755-48ee-87af-eb928016f95b@kernel.dk>
On Wed, Nov 20, 2024 at 06:20:12PM -0700, Jens Axboe wrote:
> There's no way that commit is involved, the test as quoted doesn't even
> touch write zeroes. Hence if there really is a regression here, then
> it's either not easily bisectable, some error was injected while
> bisecting, or the test itself is bimodal.
ext4 actually has some weird lazy init code using write zeroes. So
if the test actually wasn't a steady state one but only run for a short
time after init, and the mentioned commit dropped the intel hack for
deallocate as write zeroes it might actually make a difference.
To check for that do a :
/sys/block/nvmeXn1/queue/write_zeroes_max_bytes
with and without that commit.
next prev parent reply other threads:[~2024-11-21 4:57 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-11-20 21:35 [bug-report] 5-9% FIO randomwrite ext4 perf regression on 6.12.y kernel Saeed Mirzamohammadi
2024-11-21 0:00 ` Chaitanya Kulkarni
2024-11-21 1:20 ` Jens Axboe
2024-11-21 4:57 ` Christoph Hellwig [this message]
2024-11-21 14:48 ` Jens Axboe
2024-11-21 11:30 ` Phil Auld
2024-11-21 14:49 ` Jens Axboe
[not found] ` <181bcb70-e0bf-4024-80b7-e79276d6eaf7@oracle.com>
2024-11-21 21:19 ` [External] : " Phil Auld
2024-11-22 12:13 ` Christoph Hellwig
2024-11-22 17:18 ` Paul Webb
2024-11-22 18:26 ` Saeed Mirzamohammadi
2024-11-22 21:09 ` Keith Busch
2024-11-25 6:46 ` Christoph Hellwig
2024-11-25 18:28 ` Saeed Mirzamohammadi
2024-11-26 4:55 ` Christoph Hellwig
2024-11-26 18:06 ` Saeed Mirzamohammadi
2024-11-26 18:09 ` Christoph Hellwig
2024-11-26 18:13 ` Saeed Mirzamohammadi
2024-11-22 17:13 ` Paul Webb
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