From: Jakob Unterwurzacher <jakobunt@gmail.com>
To: Tejun Heo <tj@kernel.org>, Miklos Szeredi <miklos@szeredi.hu>
Cc: fuse-devel <fuse-devel@lists.sourceforge.net>,
Linux-Fsdevel <linux-fsdevel@vger.kernel.org>,
Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [fuse-devel] Horrible mmap write performance (kernel writeback issue?)
Date: Mon, 11 Apr 2016 10:04:42 +0200 [thread overview]
Message-ID: <570B5A9A.6070104@gmail.com> (raw)
In-Reply-To: <20160330184732.GO7822@mtj.duckdns.org>
On 30.03.2016 20:47, Tejun Heo wrote:
> Hmmm... cgroup writeback support shouldn't affect fuse at all as the
> backing device doesn't enable cgroup support. I probably made some
> silly mistake. Is there a simple reproducer I can play with?
Hi Tejun! A simple reproducer is at https://github.com/rfjakob/mmapwrite .
What seems to be happening in the kernel is that the estimated device bandwith
drops to zero. I'm not even sure how this works for FUSE, but that's what I
gathered from some printk debugging.
What I also found is that once mmapwrite is hung, you can unblock it for some
time by running something like
cat /dev/zero > /var/tmp/foo
mmapwrite will then steam ahead as long as cat is writing, even though encfs
writes to /tmp (tmpfs) and /var is on the ext4 disk.
Note that the hang happens regardless of the backing device, on both tmpfs and
ext4.
Best regards,
Jakob
next prev parent reply other threads:[~2016-04-11 8:04 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAPv9Zmm7WOQvMTTJjvxgXfRXzF7nes5zmJvnAo7GKqY7muWwhA@mail.gmail.com>
[not found] ` <CAPv9ZmkXnzkTAv+60GzVizjB9mrc_LwdSQ7-iimEFpeoV0Opug@mail.gmail.com>
[not found] ` <56E7C009.3070008@gmail.com>
2016-03-16 9:44 ` [fuse-devel] Horrible mmap write performance (kernel writeback issue?) Miklos Szeredi
2016-03-26 21:42 ` Jakob Unterwurzacher
2016-03-28 19:45 ` Miklos Szeredi
2016-03-30 18:47 ` Tejun Heo
[not found] ` <20160330184732.GO7822-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2016-03-31 16:58 ` Antonio SJ Musumeci
2016-04-02 6:34 ` [fuse-devel] " Sedat Dilek
2016-04-11 8:04 ` Jakob Unterwurzacher [this message]
2016-04-12 0:24 ` Tejun Heo
2016-04-12 9:24 ` Ashish Sangwan
2016-04-12 11:09 ` Tejun Heo
2016-04-13 7:20 ` Sedat Dilek
2016-04-18 21:06 ` Jakob Unterwurzacher
2016-04-20 1:35 ` Howard Cochran
2016-04-25 8:07 ` Sedat Dilek
2016-05-02 9:39 ` Sedat Dilek
[not found] ` <CA+icZUXjBim3cNhTLK3V0ko_iRsYAKV9Nhavg4pm24bNKTnp-A-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-05-10 22:55 ` Jakob Unterwurzacher
2016-05-11 7:07 ` [fuse-devel] " Sedat Dilek
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