Re: [PATCH V5 2/5] scsi: megaraid_sas: fix selection of reply queue

[Artem Bityutskiy]

On Tue, 2018-03-13 at 17:42 +0800, Ming Lei wrote:
> From 84676c1f21 (genirq/affinity: assign vectors to all possible CPUs),
> one msix vector can be created without any online CPU mapped, then
> command may be queued, and won't be notified after its completion.
> 
> This patch setups mapping between cpu and reply queue according to irq
> affinity info retrived by pci_irq_get_affinity(), and uses this info
> to choose reply queue for queuing one command.
> 
> Then the chosen reply queue has to be active, and fixes IO hang caused
> by using inactive reply queue which doesn't have any online CPU mapped.
> 
> Cc: Hannes Reinecke 
> Cc: "Martin K. Petersen" ,
> Cc: James Bottomley ,
> Cc: Christoph Hellwig ,
> Cc: Don Brace 
> Cc: Kashyap Desai 
> Cc: Laurence Oberman 
> Cc: Mike Snitzer 
> Cc: Meelis Roos 
> Cc: Artem Bityutskiy 
> Fixes: 84676c1f21e8 ("genirq/affinity: assign vectors to all possible CPUs")
> Signed-off-by: Ming Lei 

Checked v5 my Skylake Xeon and with this patch the regression that I reported 
is fixed.

Tested-by: Artem Bityutskiy 
Link: https://lkml.kernel.org/r/1519311270.2535.53.ca...@intel.com

Re: [PATCH V5 2/5] scsi: megaraid_sas: fix selection of reply queue

[Christoph Hellwig]

Same as for hpsa..

Reviewed-by: Christoph Hellwig 

RE: [PATCH V5 2/5] scsi: megaraid_sas: fix selection of reply queue

[Kashyap Desai]

> -Original Message-
> From: Ming Lei [mailto:ming@redhat.com]
> Sent: Tuesday, March 13, 2018 3:13 PM
> To: James Bottomley; Jens Axboe; Martin K . Petersen
> Cc: Christoph Hellwig; linux-s...@vger.kernel.org; linux-
> bl...@vger.kernel.org; Meelis Roos; Don Brace; Kashyap Desai; Laurence
> Oberman; Mike Snitzer; Paolo Bonzini; Ming Lei; Hannes Reinecke; James
> Bottomley; Artem Bityutskiy
> Subject: [PATCH V5 2/5] scsi: megaraid_sas: fix selection of reply queue
>
> From 84676c1f21 (genirq/affinity: assign vectors to all possible CPUs),
one
> msix vector can be created without any online CPU mapped, then command
> may be queued, and won't be notified after its completion.
>
> This patch setups mapping between cpu and reply queue according to irq
> affinity info retrived by pci_irq_get_affinity(), and uses this info to
choose
> reply queue for queuing one command.
>
> Then the chosen reply queue has to be active, and fixes IO hang caused
by
> using inactive reply queue which doesn't have any online CPU mapped.
>
> Cc: Hannes Reinecke 
> Cc: "Martin K. Petersen" ,
> Cc: James Bottomley ,
> Cc: Christoph Hellwig ,
> Cc: Don Brace 
> Cc: Kashyap Desai 
> Cc: Laurence Oberman 
> Cc: Mike Snitzer 
> Cc: Meelis Roos 
> Cc: Artem Bityutskiy 
> Fixes: 84676c1f21e8 ("genirq/affinity: assign vectors to all possible
CPUs")
> Signed-off-by: Ming Lei 


Side note - For a max performance, your below proposed patch/series is
required.  Without below patch, performance is going to be dropped due to
fewer reply queues are getting utilized one this particular patch is
included.
genirq/affinity: irq vector spread  among online CPUs as far as possible

Acked-by: Kashyap Desai 
Tested-by: Kashyap Desai