fuse: max_background and congestion_threshold settings

From	Nikolaus Rath <Nikolaus@rath.org>
Newsgroups	linux.kernel
Subject	fuse: max_background and congestion_threshold settings
Date	2016-11-15 17:20 +0100
Message-ID	<sDOCJ-7gp-17@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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Hello,

Could someone explain to me the meaning of the max_background and
congestion_threshold settings of the fuse module?

At first I assumed that max_background specifies the maximum number of
pending requests (i.e., requests that have been send to userspace but
for which no reply was received yet). But looking at fs/fuse/dev.c, it
looks as if not every request is included in this number. 

I also figured out that if the number of background requests (whatever
they are) exceeds the congestion threshold, fuse calls
set_bdi_congested() for the backing device. But what does this do? And
does this become a no-op if there is no backing device?


Thanks,
-Nikolaus
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fuse: max_background and congestion_threshold settings Nikolaus Rath <Nikolaus@rath.org> - 2016-11-15 17:20 +0100
  Re: [fuse-devel] fuse: max_background and congestion_threshold settings Nikolaus Rath <Nikolaus@rath.org> - 2016-11-16 20:20 +0100
    Re: [fuse-devel] fuse: max_background and congestion_threshold settings Nikolaus Rath <Nikolaus@rath.org> - 2016-11-16 21:30 +0100
      Re: [fuse-devel] fuse: max_background and congestion_threshold settings Nikolaus Rath <Nikolaus@rath.org> - 2016-11-22 23:50 +0100
        Re: [fuse-devel] fuse: max_background and congestion_threshold settings Nikolaus Rath <Nikolaus@rath.org> - 2016-11-23 00:50 +0100

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