From: "Vlastimil Babka (SUSE)" <vbabka@kernel.org>
To: Christoph Hellwig <hch@infradead.org>,
changfengnan <changfengnan@bytedance.com>
Cc: Dave Chinner <david@fromorbit.com>,
Harry Yoo <harry.yoo@oracle.com>, Hao Li <hao.li@linux.dev>,
guzebing <guzebing1612@gmail.com>,
brauner@kernel.org, djwong@kernel.org, linux-xfs@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
guzebing@bytedance.com, syzbot@syzkaller.appspotmail.com,
linux-mm@kvack.org
Subject: Re: [PATCH v3] iomap: add allocation cache for iomap_dio
Date: Tue, 17 Mar 2026 10:21:08 +0100 [thread overview]
Message-ID: <aab8aebb-9703-4b6d-8ac6-e4811e972898@kernel.org> (raw)
In-Reply-To: <abkbE_zh79iCd5zs@infradead.org>
On 3/17/26 10:12, Christoph Hellwig wrote:
> On Tue, Mar 17, 2026 at 04:33:24PM +0800, changfengnan wrote:
>> > IO is not my area but getting from 1.19M to 1.20M doesn't look like it's
>> > worth the custom code? (possibly from 1.17M to 1.20M it also wasn't).
>> Yes, at least for now, there’s no need for a per-CPU.
>> It might be better to replace kmalloc with a new cache, but my tests so far
>> haven’t shown any performance improvements. I’ll look into it further.
>
> Does using a kmem_cache help? That should generally be a nice win
> anyway due to keeping the objects together.
I think that's exactly what "It might be better to replace kmalloc with a
new cache" meant, and apparently with no improvements.
You might want to try create it with SLAB_NO_MERGE flag so it's really a
separate cache. Custom sheaf_capacity might also achieve that effect, but in
order to have deterministic results, the flag is a sure way.
prev parent reply other threads:[~2026-03-17 9:21 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-15 2:11 [PATCH v3] iomap: add allocation cache for iomap_dio guzebing
2026-01-15 5:02 ` Dave Chinner
2026-03-16 11:22 ` changfengnan
2026-03-16 16:54 ` Vlastimil Babka (SUSE)
2026-03-17 7:28 ` changfengnan
2026-03-17 8:27 ` Vlastimil Babka (SUSE)
2026-03-17 8:33 ` changfengnan
2026-03-17 9:12 ` Christoph Hellwig
2026-03-17 9:19 ` changfengnan
2026-03-17 9:21 ` Vlastimil Babka (SUSE) [this message]
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