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From: Tejun Heo <tj@kernel.org>
To: Michael Stapelberg <michael+lkml@stapelberg.ch>
Cc: Miklos Szeredi <miklos@szeredi.hu>,
	Jack Smith <smith.jack.sidman@gmail.com>,
	fuse-devel <fuse-devel@lists.sourceforge.net>,
	linux-fsdevel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [fuse-devel] Writing to FUSE via mmap extremely slow (sometimes) on some machines?
Date: Tue, 3 Mar 2020 09:25:12 -0500	[thread overview]
Message-ID: <20200303142512.GC189690@mtj.thefacebook.com> (raw)
In-Reply-To: <CANnVG6=9mYACk5tR2xD08r_sGWEeZ0rHZAmJ90U-8h3+iSMvbA@mail.gmail.com>

On Tue, Mar 03, 2020 at 03:21:47PM +0100, Michael Stapelberg wrote:
> Find attached trace.log (cat /sys/kernel/debug/tracing/trace) and
> fuse-debug.log (FUSE daemon with timestamps).
> 
> Does that tell you something, or do we need more data? (If so, how?)

This is likely the culprit.

 .... 1319822.406198: balance_dirty_pages: ... bdi_dirty=68 dirty_ratelimit=28 ...

For whatever reason, bdp calculated that the dirty throttling
threshold for the fuse device is 28 pages which is extremely low. Need
to track down how that number came to be. I'm afraid from here on it'd
mostly be reading source code and sprinkling printks around but the
debugging really comes down to figuring out how we ended up with 68
and 28.

Thanks.

-- 
tejun

  reply	other threads:[~2020-03-03 14:25 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-24 13:29 Writing to FUSE via mmap extremely slow (sometimes) on some machines? Michael Stapelberg
     [not found] ` <CACQJH27s4HKzPgUkVT+FXWLGqJAAMYEkeKe7cidcesaYdE2Vog@mail.gmail.com>
     [not found]   ` <CANnVG6=Ghu5r44mTkr0uXx_ZrrWo2N5C_UEfM59110Zx+HApzw@mail.gmail.com>
     [not found]     ` <CAJfpegvzhfO7hg1sb_ttQF=dmBeg80WVkV8srF3VVYHw9ybV0w@mail.gmail.com>
     [not found]       ` <CANnVG6kSJJw-+jtjh-ate7CC3CsB2=ugnQpA9ACGFdMex8sftg@mail.gmail.com>
2020-02-26 19:59         ` [fuse-devel] " Miklos Szeredi
2020-03-03 10:34           ` Michael Stapelberg
2020-03-03 10:34             ` Michael Stapelberg
2020-03-03 13:04           ` Tejun Heo
2020-03-03 14:03             ` Michael Stapelberg
2020-03-03 14:03               ` Michael Stapelberg
2020-03-03 14:13               ` Tejun Heo
2020-03-03 14:21                 ` Michael Stapelberg
2020-03-03 14:21                   ` Michael Stapelberg
2020-03-03 14:25                   ` Tejun Heo [this message]
2020-03-05 14:45                     ` Michael Stapelberg
2020-03-09 14:32                       ` Michael Stapelberg
2020-03-09 14:32                         ` Michael Stapelberg
2020-03-09 14:36                         ` Miklos Szeredi
2020-03-09 14:36                           ` Miklos Szeredi
2020-03-09 15:11                           ` Michael Stapelberg
2020-03-09 15:11                             ` Michael Stapelberg
2020-03-12 15:45                             ` Michael Stapelberg
2020-03-12 15:45                               ` Michael Stapelberg

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