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

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

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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