From: Linus Torvalds <torvalds@linux-foundation.org>
To: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Jens Axboe <axboe@kernel.dk>, Michal Hocko <mhocko@suse.com>,
Dave Chinner <david@fromorbit.com>, Mel Gorman <mgorman@suse.de>,
Johannes Weiner <hannes@cmpxchg.org>, Tejun Heo <tj@kernel.org>
Subject: Re: [PATCH v2] mm: implement write-behind policy for sequential file writes
Date: Fri, 20 Sep 2019 16:05:17 -0700 [thread overview]
Message-ID: <CAHk-=whmCZvYcR10Pe9fEy912fc8xywbiP9mn054Jg_9+0TqCg@mail.gmail.com> (raw)
In-Reply-To: <156896493723.4334.13340481207144634918.stgit@buzz>
On Fri, Sep 20, 2019 at 12:35 AM Konstantin Khlebnikov
<khlebnikov@yandex-team.ru> wrote:
>
> This patch implements write-behind policy which tracks sequential writes
> and starts background writeback when file have enough dirty pages.
Apart from a spelling error ("contigious"), my only reaction is that
I've wanted this for the multi-file writes, not just for single big
files.
Yes, single big files may be a simpler and perhaps the "10% effort for
90% of the gain", and thus the right thing to do, but I do wonder if
you've looked at simply extending it to cover multiple files when
people copy a whole directory (or unpack a tar-file, or similar).
Now, I hear you say "those are so small these days that it doesn't
matter". And maybe you're right. But partiocularly for slow media,
triggering good streaming write behavior has been a problem in the
past.
So I'm wondering whether the "writebehind" state should perhaps be
considered be a process state, rather than "struct file" state, and
also start triggering for writing smaller files.
Maybe this was already discussed and people decided that the big-file
case was so much easier that it wasn't worth worrying about
writebehind for multiple files.
Linus
next prev parent reply other threads:[~2019-09-20 23:05 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-20 7:35 [PATCH v2] mm: implement write-behind policy for sequential file writes Konstantin Khlebnikov
2019-09-20 7:39 ` Konstantin Khlebnikov
2019-09-23 14:52 ` Tejun Heo
2019-09-23 15:06 ` Konstantin Khlebnikov
2019-09-23 15:19 ` Tejun Heo
2019-09-24 7:39 ` Dave Chinner
2019-09-24 9:00 ` Konstantin Khlebnikov
2019-09-25 7:18 ` Dave Chinner
2019-09-25 8:15 ` Konstantin Khlebnikov
2019-09-25 23:25 ` Dave Chinner
2019-09-25 12:54 ` Theodore Y. Ts'o
2019-09-24 19:08 ` Linus Torvalds
2019-09-25 8:00 ` Dave Chinner
2019-09-20 23:05 ` Linus Torvalds [this message]
2019-09-20 23:10 ` Linus Torvalds
2019-09-23 15:36 ` Jens Axboe
2019-09-23 16:05 ` Konstantin Khlebnikov
2019-09-24 9:29 ` Konstantin Khlebnikov
2019-09-22 7:47 ` kbuild test robot
2019-09-23 0:36 ` [mm] e0e7df8d5b: will-it-scale.per_process_ops -7.3% regression kernel test robot
2019-09-23 19:11 ` Konstantin Khlebnikov
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