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Message-ID: <44F600A9.4050207@us.ibm.com>
Date: Wed, 30 Aug 2006 14:18:33 -0700
From: "Darrick J. Wong" <djwong@...ibm.com>
To: "Darrick J. Wong" <djwong@...ibm.com>,
linux-scsi <linux-scsi@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] aic94xx: Increase can_queue for better performance
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@...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);
-
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