From: "Benoît Canet" <benoit.canet@irqsave.net>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Chris Friesen <chris.friesen@windriver.com>, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] is there a limit on the number of in-flight I/O operations?
Date: Sat, 19 Jul 2014 10:45:37 +0200 [thread overview]
Message-ID: <20140719084537.GA3058@irqsave.net> (raw)
In-Reply-To: <53CA1D06.9090601@redhat.com>
The Saturday 19 Jul 2014 à 09:23:50 (+0200), Paolo Bonzini wrote :
> Il 19/07/2014 08:27, Chris Friesen ha scritto:
> > Does it track in-flight operations though? Or just how many operations
> > can be requested in a given amount of time?
>
> It should track in flight operations. However, I'm not sure it supports
> the iops=0 case properly, since I do not see anything in
> tracked_request_end that ceases the accounting of the current operation.
> Benoit, can you answer?
>
> Paolo
I think in the throttling case the number of in flight operation is limited by
the emulated hardware queue. Else request would pile up and throttling would be
inefective.
So this number should be around: #define VIRTIO_PCI_QUEUE_MAX 64 or something like than that.
>
> > If it tracks how many operations can be requested, then if the "iops"
> > parameter is larger than what the server can maintain then the number of
> > in-flight operations could still grow indefinitely.
> >
> > I suppose I'll have to check the code. :)
>
next prev parent reply other threads:[~2014-07-19 8:46 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-18 14:58 [Qemu-devel] is there a limit on the number of in-flight I/O operations? Chris Friesen
2014-07-18 15:24 ` Paolo Bonzini
2014-07-18 16:22 ` Chris Friesen
2014-07-18 20:13 ` Paolo Bonzini
2014-07-18 22:48 ` Chris Friesen
2014-07-19 5:49 ` Paolo Bonzini
2014-07-19 6:27 ` Chris Friesen
2014-07-19 7:23 ` Paolo Bonzini
2014-07-19 8:45 ` Benoît Canet [this message]
2014-07-21 14:59 ` Chris Friesen
2014-07-21 15:15 ` Benoît Canet
2014-07-21 15:35 ` Chris Friesen
2014-07-21 15:54 ` Benoît Canet
2014-07-21 16:10 ` Benoît Canet
2014-08-23 0:59 ` Chris Friesen
2014-08-23 7:56 ` Benoît Canet
2014-08-25 15:12 ` Chris Friesen
2014-08-25 17:43 ` Chris Friesen
2015-08-27 16:37 ` Stefan Hajnoczi
2015-08-27 16:33 ` Stefan Hajnoczi
2014-08-25 21:50 ` Chris Friesen
2014-08-27 5:43 ` Chris Friesen
2015-05-14 13:42 ` Andrey Korolyov
2015-08-26 17:10 ` Andrey Korolyov
2015-08-26 23:31 ` Josh Durgin
2015-08-26 23:47 ` Andrey Korolyov
2015-08-27 0:56 ` Josh Durgin
2015-08-27 16:48 ` Stefan Hajnoczi
2015-08-27 17:05 ` Stefan Hajnoczi
2015-08-27 16:49 ` Stefan Hajnoczi
2015-08-28 0:31 ` Josh Durgin
2015-08-28 8:31 ` Andrey Korolyov
2014-07-21 19:47 ` Benoît Canet
2014-07-21 21:12 ` Chris Friesen
2014-07-21 22:04 ` Benoît Canet
2014-07-18 15:54 ` Andrey Korolyov
2014-07-18 16:26 ` Chris Friesen
2014-07-18 16:30 ` Andrey Korolyov
2014-07-18 16:46 ` Chris Friesen
[not found] <1000957815.25879188.1441820902018.JavaMail.zimbra@redhat.com>
2015-09-09 18:51 ` Jason Dillaman
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