From: Paul Brook <paul@codesourcery.com>
To: "Andreas Färber" <afaerber@suse.de>
Cc: Zhi Yong Wu <zwu.kernel@gmail.com>,
Stefan Hajnoczi <stefanha@gmail.com>,
Alexander Graf <agraf@suse.de>,
qemu-devel@nongnu.org, Stefan Weil <sw@weilnetz.de>
Subject: Re: [Qemu-devel] Memory: how to determine the max memory size of one VM?
Date: Sat, 11 Feb 2012 00:46:23 +0000 [thread overview]
Message-ID: <201202110046.24433.paul@codesourcery.com> (raw)
In-Reply-To: <4F35B555.2050308@suse.de>
> Am 11.02.2012 00:25, schrieb Paul Brook:
> >> ii) Some tracing of mine indicates QEMU has a highly dynamic memory
> >> usage during runtime, be it due to network layer, block layer or
> >> whatever exactly.
> >
> > We do? Significant compared to the size of guest ram? That sounds like a
> > bug.
>
> Attached is a gnuplot from a simpletrace trace file while installing a
> SLES 11 SP2 Release Candidate over slirp to virtio with -m 8G on an 8
> GiB host (post-1.0 master).
>
> It's not fully scientifically correct (it doesn't take into account
> memory allocations not traced by QEMU itself, like pthreads) but it
> suggests that after the initial surge to ~8.7 GB we have a fluctuation
> of ~0.2 GB for 8 GiB guest RAM. It's larger than I'd expect at least.
>
> Since the user was close to the limit, this lead to an abort. In their
> case it was a pthread_create() that failed, and we used tap + virtio.
Hmm, yes, we're clearly allocating some very large buffers somewhere.
Paul
next prev parent reply other threads:[~2012-02-11 0:46 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-10 9:47 [Qemu-devel] Memory: how to determine the max memory size of one VM? Zhi Yong Wu
2012-02-10 10:35 ` Stefan Hajnoczi
2012-02-10 10:36 ` Stefan Hajnoczi
2012-02-10 16:40 ` Andreas Färber
2012-02-10 23:25 ` Paul Brook
2012-02-11 0:24 ` Andreas Färber
2012-02-11 0:46 ` Paul Brook [this message]
2012-02-10 11:00 ` Zhi Yong Wu
2012-02-10 11:10 ` Stefan Hajnoczi
2012-02-10 11:23 ` Zhi Yong Wu
2012-02-10 11:31 ` Stefan Hajnoczi
2012-02-10 11:53 ` Zhi Yong Wu
2012-02-10 14:08 ` Stefan Hajnoczi
2012-02-10 14:36 ` Zhi Yong Wu
2012-02-10 16:20 ` Andreas Färber
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