Re: "multi-queue-max-queues" key not present on Xen host - is it possible to enable it?

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Thu, Apr 28, 2016 at 07:34:32PM +0000, Pawar, Sangram wrote:
> Hi,
> My name is Sangram Pawar, a developer at NetApp. I'm currently measuring the performance of multi-queue support added to the netfront driver (in Jan'16).
> 
> I noticed the backend is not advertising the "multi-queue-max-queues" key. So whenever netfront driver (freebsd vm) checks for the "multi-queue-max-queues" key, it receives error 2 due to which it continues with the single queue.
> 
> # dmesg | grep Xen\ version
> [    0.000000] Xen version: 4.3.0 (preserve-AD)
> 
> # uname -a
> Linux xenhost 3.9.11-200.fc18.x86_64 #1 SMP Mon Jul 22 21:04:50 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
> 
> # xl info
> host                   : xenhost
> release                : 3.9.11-200.fc18.x86_64
> version                : #1 SMP Mon Jul 22 21:04:50 UTC 2013
> machine                : x86_64
> nr_cpus                : 8
> max_cpu_id             : 7
> nr_nodes               : 2
> cores_per_socket       : 4
> threads_per_core       : 1
> cpu_mhz                : 2194
> hw_caps                : bfebfbff:2c100800:00000000:00003f00:17bee3ff:00000000:00000001:00000000
> virt_caps              : hvm hvm_directio
> total_memory           : 24548
> free_memory            : 452
> sharing_freed_memory   : 0
> sharing_used_memory    : 0
> outstanding_claims     : 0
> free_cpus              : 0
> xen_major              : 4
> xen_minor              : 3
> xen_extra              : .0
> xen_caps               : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32 hvm-3.0-x86_32p hvm-3.0-x86_64 
> xen_scheduler          : credit
> xen_pagesize           : 4096
> platform_params        : virt_start=0xffff800000000000
> xen_changeset          : 
> xen_commandline        : placeholder
> cc_compiler            : gcc (GCC) 4.7.2 20121109 (Red Hat 4.7.2-8)
> cc_compile_by          : root
> cc_compile_domain      : 
> cc_compile_date        : Fri Mar 14 11:56:09 EDT 2014
> xend_config_format     : 4
> 
> 
> 
> I followed the thread (http://lists.xenproject.org/archives/html/xen-devel/2013-06/msg02654.html) and noticed the dl at the bottom, so sending you few questions.
> 
> 
> From this thread:
> In addition to the feature flag, a backend which supports feature-multi-queue would advertise a maximum number of queues, via the key:
> /local/domain/0/backend/vif/X/Y/multi-queue-max-queues
> 
> So it is clear that the backend doesn't support multi queue VIFs. Could you please tell the reason? Am I running too old Xen version? If yes, which Xen version has support for it? If not, is it possible to enable this feature so backend can advertise it using this key?
> 

It is your version of backend. Aka - the driver in Linux kernel.

I would recommend you upgrade to say 4.4.

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