Re: [PATCH v3] aic94xx: Increase can_queue for better performance

["Darrick J. Wong" <djwong@us.ibm.com>]

Darrick J. Wong wrote:
> Hi all,
> 
> Below is a patch that sets can_queue in the aic94xx driver's scsi_host
> to better performing values than what's there currently.  It seems that
> asd_ha->seq.can_queue reflects the number of requests that can be
> queued per controller; so long as there's one scsi_host per controller,
> it seems logical that the scsi_host ought to have the same can_queue
> value.  To the best of my (still limited) knowledge, this method
> provides the correct value.
> 
> The effect of leaving this value set to 1 is terrible performance in
> the case of either (a) certain Maxtor SAS drives flying solo or (b)
> flooding several disks with I/O simultaneously (md-raid).  There may be
> more scenarios where we see similar problems that I haven't uncovered.

Let's try this again, after kicking Thunderbird in the head.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>

diff --git a/drivers/scsi/aic94xx/aic94xx_init.c b/drivers/scsi/aic94xx/aic94xx_init.c
index 3e25e31..5c6d457 100644
--- a/drivers/scsi/aic94xx/aic94xx_init.c
+++ b/drivers/scsi/aic94xx/aic94xx_init.c
@@ -623,6 +623,8 @@ static int __devinit asd_pci_probe(struc
 		   asd_ha->hw_prof.bios.present ? "build " : "not present",
 		   asd_ha->hw_prof.bios.bld);
 
+	shost->can_queue = asd_ha->seq.can_queue;
+
 	if (use_msi)
 		pci_enable_msi(asd_ha->pcidev);