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From: Johannes Weiner <>
To: Matthew Wilcox <>
Cc: Shakeel Butt <>,
	Andrew Morton <>,
	Linux MM <>,
	linux-fsdevel <>,
	LKML <>,
	Kernel Team <>
Subject: Re: xarray breaks thrashing detection and cgroup isolation
Date: Fri, 24 May 2019 13:06:42 -0400	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Fri, May 24, 2019 at 09:11:46AM -0700, Matthew Wilcox wrote:
> On Thu, May 23, 2019 at 03:59:33PM -0400, Johannes Weiner wrote:
> > My point is that we cannot have random drivers' internal data
> > structures charge to and pin cgroups indefinitely just because they
> > happen to do the modprobing or otherwise interact with the driver.
> > 
> > It makes no sense in terms of performance or cgroup semantics.
> But according to Roman, you already have that problem with the page
> cache.
> So this argument doesn't make sense to me.

You haven't addressed the rest of the argument though: why every user
of the xarray, and data structures based on it, should incur the
performance cost of charging memory to a cgroup, even when we have no
interest in tracking those allocations on behalf of a cgroup.

Which brings me to repeating the semantics argument: it doesn't make
sense to charge e.g. driver memory, which is arguably a shared system
resource, to whoever cgroup happens to do the modprobe / ioctl etc.

Anyway, this seems like a fairly serious regression, and it would make
sense to find a self-contained, backportable fix instead of something
that has subtle implications for every user of the xarray / ida code.

  reply	other threads:[~2019-05-24 17:06 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-23 17:43 Johannes Weiner
2019-05-23 18:37 ` Matthew Wilcox
2019-05-23 18:49   ` Shakeel Butt
2019-05-23 19:00     ` Matthew Wilcox
2019-05-23 19:21       ` Johannes Weiner
2019-05-23 19:41         ` Matthew Wilcox
2019-05-23 19:59           ` Johannes Weiner
2019-05-24 16:11             ` Matthew Wilcox
2019-05-24 17:06               ` Johannes Weiner [this message]
2019-05-24 17:18                 ` Shakeel Butt

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