From: Paolo Bonzini <pbonzini@redhat.com>
To: "Benoît Canet" <benoit@irqsave.net>
Cc: kwolf@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com
Subject: Re: [Qemu-devel] [PATCH V4 3/5] block: Enable the new throttling code in the block layer.
Date: Thu, 08 Aug 2013 17:30:25 +0200 [thread overview]
Message-ID: <5203B991.90405@redhat.com> (raw)
In-Reply-To: <1375972194-3090-4-git-send-email-benoit@irqsave.net>
Il 08/08/2013 16:29, Benoît Canet ha scritto:
> tip: Do not ever use the cfg scheduler in the guest with this code.
> It gives incorrect throttling.
This is not really accurate; the cfq scheduler reorders reads and writes
to have longer bursts, and these sometimes exceed the rate you set. I
understood this is mostly for separate rd/wr settings, or did you
reproduce it with "total" rates too?
Also, it would be better to have a workaround for this. Perhaps we
could simply make the default value of max nonzero? In the old
throttling code the slice time is 0.1s, so perhaps we could see what
happens with max=0.1*avg.
Paolo
next prev parent reply other threads:[~2013-08-08 15:31 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-08 14:29 [Qemu-devel] [PATCH V4 0/5] Continuous Leaky Bucket Throttling Benoît Canet
2013-08-08 14:29 ` [Qemu-devel] [PATCH V4 1/5] throttle: Add a new throttling API implementing continuous leaky bucket Benoît Canet
2013-08-08 14:29 ` [Qemu-devel] [PATCH V4 2/5] throttle: Add units tests Benoît Canet
2013-08-08 14:29 ` [Qemu-devel] [PATCH V4 3/5] block: Enable the new throttling code in the block layer Benoît Canet
2013-08-08 15:30 ` Paolo Bonzini [this message]
2013-08-08 15:43 ` [Qemu-devel] [PATCH V4 3/5] block: Enable the new throttling code in the block layer.o Benoît Canet
2013-08-08 15:56 ` [Qemu-devel] [PATCH V4 3/5] block: Enable the new throttling code in the block layer Benoît Canet
2013-08-08 14:29 ` [Qemu-devel] [PATCH V4 4/5] block: Add support for throttling burst max in QMP and the command line Benoît Canet
2013-08-08 14:29 ` [Qemu-devel] [PATCH V4 5/5] block: Add iops_sector_count to do the iops accounting for a given io size Benoît Canet
2013-08-09 12:05 ` [Qemu-devel] [PATCH V4 0/5] Continuous Leaky Bucket Throttling* Benoît Canet
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