Re: IB_CQ_VECTOR_LEAST_ATTACHED

[Shirley Ma <shirley.ma-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>]

On 12/04/2014 10:43 AM, Bart Van Assche wrote:
> On 12/04/14 17:47, Shirley Ma wrote:
>> What's the history of this patch?
>>     http://lists.openfabrics.org/pipermail/general/2008-May/050813.html
>>
>> I am working on multiple QPs workload. And I created a similar approach
>> with IB_CQ_VECTOR_LEAST_ATTACHED, which can bring up about 17% small I/O
>> performance. I think this CQ_VECTOR loading balance should be maintained
>> in provider not the caller. I didn't see this patch was submitted to
>> mainline kernel, wonder any reason behind?
> 
> My interpretation is that an approach similar to IB_CQ_VECTOR_LEAST_ATTACHED is useful on single-socket systems but suboptimal on multi-socket systems. Hence the code for associating CQ sets with CPU sockets in the SRP initiator. These changes have been queued for kernel 3.19. See also branch drivers-for-3.19 in git repo git://git.infradead.org/users/hch/scsi-queue.git.

What I did is that I manually controlled IRQ and working thread on the same socket. The CQ is created when mounting the file system in NFS/RDMA, but the workload thread might start from different socket, so per-cpu based implementation might not apply. I will look at SRP implementation.

Thanks,
Shirley
 
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