Re: [PATCH 2 08/24] hpsa: choose number of reply queues more intelligently.

[scameron@beardog.cce.hp.com]

On Mon, Jun 02, 2014 at 02:27:51AM -0700, Christoph Hellwig wrote:
> On Thu, May 29, 2014 at 10:53:02AM -0500, Stephen M. Cameron wrote:
> > From: Stephen M. Cameron <scameron@beardog.cce.hp.com>
> > 
> > No sense having 8 or 16 reply queues if you only have 4 cpus,
> > and likewise no sense limiting to 8 reply queues if you have
> > many more cpus.
> 
> I've applied this as it looks good as-is, but shouldn't we also
> cap the number of MSI-X vectors in common code so that we avoid
> adding this as boilerplate code to lots of drivers?

Maybe so.  Thinking about CPU hotplug, is num_online_cpus()
the right cap?  Maybe num_possible_cpus() is better in case
additional cpus coming online are anticipated?

-- steve

> 
> > 
> > Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
> > Reviewed-by: Mike Miller <michael.miller@canonical.com>
> > Reviewed-by: Scott Teel <scott.teel@hp.com>
> > ---
> >  drivers/scsi/hpsa.c     |    2 ++
> >  drivers/scsi/hpsa_cmd.h |    2 +-
> >  2 files changed, 3 insertions(+), 1 deletions(-)
> > 
> > diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c
> > index b1ecfd8..b903e86 100644
> > --- a/drivers/scsi/hpsa.c
> > +++ b/drivers/scsi/hpsa.c
> > @@ -6157,6 +6157,8 @@ static void hpsa_interrupt_mode(struct ctlr_info *h)
> >  	if (pci_find_capability(h->pdev, PCI_CAP_ID_MSIX)) {
> >  		dev_info(&h->pdev->dev, "MSIX\n");
> >  		h->msix_vector = MAX_REPLY_QUEUES;
> > +		if (h->msix_vector > num_online_cpus())
> > +			h->msix_vector = num_online_cpus();
> >  		err = pci_enable_msix(h->pdev, hpsa_msix_entries,
> >  				      h->msix_vector);
> >  		if (err > 0) {
> > diff --git a/drivers/scsi/hpsa_cmd.h b/drivers/scsi/hpsa_cmd.h
> > index db89245..104b67b 100644
> > --- a/drivers/scsi/hpsa_cmd.h
> > +++ b/drivers/scsi/hpsa_cmd.h
> > @@ -615,7 +615,7 @@ struct TransTable_struct {
> >  	u32            RepQCount;
> >  	u32            RepQCtrAddrLow32;
> >  	u32            RepQCtrAddrHigh32;
> > -#define MAX_REPLY_QUEUES 8
> > +#define MAX_REPLY_QUEUES 64
> >  	struct vals32  RepQAddr[MAX_REPLY_QUEUES];
> >  };
> >  
> > 
> > --
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