[PATCH] NVMe: Set affinity after allocating request queues

[Jens Axboe]

On 09/23/2015 02:37 PM, Keith Busch wrote:
> On Thu, 3 Sep 2015, Keith Busch wrote:
>> The asynchronous namespace scanning caused affinity hints to be set
>> before
>> its tagset initialized, so there was no cpu mask to set the hint. This
>> patch moves the affinity hint setting to after namespaces are scanned.
>
> Hi Jens,
>
> Would it be okay to get this merged in for 4.3? The affinity hint is
> very important to top out performance, so this should be considered a
> bug that the setting wasn't correct.

I haven't seen this patch, but yes if it's not setting the right hints, 
then it should be fixed as that is certainly a potentially big 
performance issue. In general we're still in dire need of having a 
proper way of having this done without a lot of driver interaction. I'd 
really love to see a framework that just has the driver ask blk-mq for a 
set of handlers, and blk-mq will set with the hints that it has already 
assigned. I might even have promised to write this, I should get around 
to do that... But I don't think it should be a gating factor for this 
fix, though it still needs to get done.

-- 
Jens Axboe