From: Shakeel Butt <shakeelb@google.com>
To: Daniel Xu <dxu@dxuuu.xyz>
Cc: bpf <bpf@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Linux MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Kernel Team <kernel-team@fb.com>,
jolsa@kernel.org, Johannes Weiner <hannes@cmpxchg.org>,
Yonghong Song <yhs@fb.com>
Subject: Re: [RFC bpf-next 0/1] bpf: Add page cache iterator
Date: Thu, 8 Apr 2021 14:33:43 -0700 [thread overview]
Message-ID: <CALvZod4kefNWPAwKZdpO8z29sJ2jDh74_C5Y_FSgXFB8s5ZXGA@mail.gmail.com> (raw)
In-Reply-To: <cover.1617831474.git.dxu@dxuuu.xyz>
On Wed, Apr 7, 2021 at 2:47 PM Daniel Xu <dxu@dxuuu.xyz> wrote:
>
> There currently does not exist a way to answer the question: "What is in
> the page cache?". There are various heuristics and counters but nothing
> that can tell you anything like:
>
> * 3M from /home/dxu/foo.txt
> * 5K from ...
> * etc.
>
So, you need the list of inodes for a filesystem that are in memory.
With that list, you can open, map and do mincore on them?
I don't know of a way to get that inode list.
> The answer to the question is particularly useful in the stacked
> container world. Stacked containers implies multiple containers are run
> on the same physical host. Memory is precious resource on some (if not
> most) of these systems. On these systems, it's useful to know how much
> duplicated data is in the page cache. Once you know the answer, you can
> do something about it. One possible technique would be bind mount common
> items from the root host into each container.
>
Oh you want to share page cache between different containers/jobs?
That would complicate charging.
next prev parent reply other threads:[~2021-04-08 21:33 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-07 21:46 [RFC bpf-next 0/1] bpf: Add page cache iterator Daniel Xu
2021-04-07 21:46 ` [RFC bpf-next 1/1] bpf: Introduce iter_pagecache Daniel Xu
2021-04-08 6:14 ` Matthew Wilcox
2021-04-08 19:48 ` Daniel Xu
2021-04-08 21:29 ` Matthew Wilcox
2021-04-08 8:19 ` Christian Brauner
2021-04-08 20:44 ` Daniel Xu
2021-04-08 16:45 ` Al Viro
2021-04-08 20:49 ` Daniel Xu
2021-04-08 21:04 ` Al Viro
2021-04-08 22:11 ` Dave Chinner
2021-04-08 7:51 ` [RFC bpf-next 0/1] bpf: Add page cache iterator Christian Brauner
2021-04-08 16:08 ` Daniel Xu
2021-04-08 21:33 ` Shakeel Butt [this message]
2021-04-08 23:13 ` Darrick J. Wong
2021-04-09 0:24 ` Daniel Xu
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