From: annie li <annie.li@oracle.com>
To: Ian Campbell <ian.campbell@citrix.com>,
xen-devel <xen-devel@lists.xen.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Wei Liu <wei.liu2@citrix.com>,
David Vrabel <david.vrabel@citrix.com>
Subject: Re: netfront/netback multiqueue exhausting grants
Date: Wed, 20 Jan 2016 11:18:48 -0500 [thread overview]
Message-ID: <569FB368.6050306@oracle.com> (raw)
In-Reply-To: <1453292623.26343.95.camel@citrix.com>
On 2016/1/20 7:23, Ian Campbell wrote:
> There have been a few reports recently[0] which relate to a failure of
> netfront to allocate sufficient grant refs for all the queues:
>
> [ 0.533589] xen_netfront: can't alloc rx grant refs
> [ 0.533612] net eth0: only created 31 queues
>
> Which can be worked around by increasing the number of grants on the
> hypervisor command line or by limiting the number of queues permitted by
> either back or front using a module param (which was broken but is now
> fixed on both sides, but I'm not sure it has been backported everywhere
> such that it is a reliable thing to always tell users as a workaround).
Following are the patches to fix module param, they exist since v4.3.
xen-netfront: respect user provided max_queues
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=32a844056fd43dda647e1c3c6b9983bdfa04d17d
xen-netback: respect user provided max_queues
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=4c82ac3c37363e8c4ded6a5fe1ec5fa756b34df3
>
> Is there any plan to do anything about the default/out of the box
> experience? Either limiting the number of queues or making both ends cope
> more gracefully with failure to create some queues (or both) might be
> sufficient?
We run into similar issue recently, and guess it is better to suggest
user to set netback module parameter with the default value as 8? see
this link,
http://wiki.xenproject.org/wiki/Xen-netback_and_xen-netfront_multi-queue_performance_testing
Probably more test are needed to get the default number of best experience.
>
> I think the crash after the above in the first link at [0] is fixed? I
> think that was the purpose of ca88ea1247df "xen-netfront: update num_queues
> to real created" which was in 4.3.
Correct.
Thanks
Annie
>
> Ian.
>
> [0] http://lists.xen.org/archives/html/xen-users/2016-01/msg00100.html
> http://lists.xen.org/archives/html/xen-users/2016-01/msg00072.html
> some before hte xmas break too IIRC
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel
next prev parent reply other threads:[~2016-01-20 16:18 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-20 12:23 netfront/netback multiqueue exhausting grants Ian Campbell
2016-01-20 14:40 ` Boris Ostrovsky
2016-01-20 14:52 ` Ian Campbell
2016-01-20 15:02 ` David Vrabel
2016-01-20 15:10 ` Boris Ostrovsky
2016-01-20 15:16 ` Ian Campbell
2016-01-21 10:12 ` Ian Campbell
2016-01-21 10:25 ` Wei Liu
2016-01-21 10:37 ` Ian Campbell
2016-01-21 10:52 ` Wei Liu
2016-01-20 16:18 ` annie li [this message]
2016-01-21 10:56 ` David Vrabel
2016-01-21 12:19 ` Ian Campbell
2016-01-21 14:17 ` David Vrabel
2016-01-21 15:11 ` annie li
2016-01-22 3:36 ` Bob Liu
2016-01-22 7:53 ` Jan Beulich
2016-01-22 10:40 ` Bob Liu
2016-01-22 11:02 ` Jan Beulich
2016-01-23 0:29 ` Bob Liu
2016-01-25 9:53 ` Jan Beulich
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