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From: Jingbo Xu <jefflexu@linux.alibaba.com>
To: Alexander Larsson <alexl@redhat.com>, lsf-pc@lists.linux-foundation.org
Cc: linux-fsdevel@vger.kernel.org,
	Amir Goldstein <amir73il@gmail.com>,
	Christian Brauner <brauner@kernel.org>,
	Gao Xiang <hsiangkao@linux.alibaba.com>,
	Giuseppe Scrivano <gscrivan@redhat.com>,
	Dave Chinner <david@fromorbit.com>,
	Vivek Goyal <vgoyal@redhat.com>,
	Miklos Szeredi <miklos@szeredi.hu>
Subject: Re: [LSF/MM/BFP TOPIC] Composefs vs erofs+overlay
Date: Sat, 4 Mar 2023 08:46:49 +0800	[thread overview]
Message-ID: <6ecbe86b-f97f-30f6-9a6e-cb3090ec35cf@linux.alibaba.com> (raw)
In-Reply-To: <CAL7ro1E7KY5yUJOLu6TY0RtAC5304sM3Lvk=zSCrqDrxTPW2og@mail.gmail.com>



On 3/3/23 9:57 PM, Alexander Larsson wrote:
> On Mon, Feb 27, 2023 at 10:22 AM Alexander Larsson <alexl@redhat.com> wrote:
> 
> * Erofs on top of direct-io enabled loopback causes quite a drop in
>   performance, which I don't really understand. Especially since its
>   reporting the same memory use as non-direct io. I guess the
>   double-cacheing in the later case isn't properly attributed to the
>   cgroup so the difference is not measured. However, why would the
>   double cache improve performance?  Maybe I'm not completely
>   understanding how these things interact.
> 

Loop in BUFFERED mode actually calls .read_iter() of the backing file to
read from it, e.g. ext4_file_read_iter()->generic_file_read_iter(),
where heuristic readahead is also done.

-- 
Thanks,
Jingbo

  parent reply	other threads:[~2023-03-04  0:46 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-27  9:22 [LSF/MM/BFP TOPIC] Composefs vs erofs+overlay Alexander Larsson
2023-02-27 10:45 ` Gao Xiang
2023-02-27 10:58   ` Christian Brauner
2023-04-27 16:11     ` [Lsf-pc] " Amir Goldstein
2023-03-01  3:47   ` Jingbo Xu
2023-03-03 14:41     ` Alexander Larsson
2023-03-03 15:48       ` Gao Xiang
2023-02-27 11:37 ` Jingbo Xu
2023-03-03 13:57 ` Alexander Larsson
2023-03-03 15:13   ` Gao Xiang
2023-03-03 17:37     ` Gao Xiang
2023-03-04 14:59       ` Colin Walters
2023-03-04 15:29         ` Gao Xiang
2023-03-04 16:22           ` Gao Xiang
2023-03-07  1:00           ` Colin Walters
2023-03-07  3:10             ` Gao Xiang
2023-03-07 10:15     ` Christian Brauner
2023-03-07 11:03       ` Gao Xiang
2023-03-07 12:09       ` Alexander Larsson
2023-03-07 12:55         ` Gao Xiang
2023-03-07 15:16         ` Christian Brauner
2023-03-07 19:33           ` Giuseppe Scrivano
2023-03-08 10:31             ` Christian Brauner
2023-03-07 13:38       ` Jeff Layton
2023-03-08 10:37         ` Christian Brauner
2023-03-04  0:46   ` Jingbo Xu [this message]
2023-03-06 11:33   ` Alexander Larsson
2023-03-06 12:15     ` Gao Xiang
2023-03-06 15:49     ` Jingbo Xu
2023-03-06 16:09       ` Alexander Larsson
2023-03-06 16:17         ` Gao Xiang
2023-03-07  8:21           ` Alexander Larsson
2023-03-07  8:33             ` Gao Xiang
2023-03-07  8:48               ` Gao Xiang
2023-03-07  9:07               ` Alexander Larsson
2023-03-07  9:26                 ` Gao Xiang
2023-03-07  9:38                   ` Gao Xiang
2023-03-07  9:56                     ` Alexander Larsson
2023-03-07 10:06                       ` Gao Xiang
2023-03-07  9:46                   ` Alexander Larsson
2023-03-07 10:01                     ` Gao Xiang
2023-03-07 10:00       ` Jingbo Xu

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