Re: REGRESSION in 2.6.13-rc1: Massive slowdown with Adaptec SCSI

[Neil Brown]

On Tuesday July 5, neilb@xxxxxxxxxxxxxxx wrote:
> On Tuesday July 5, matthew@xxxxxx wrote:
> > On Tue, Jul 05, 2005 at 11:08:17AM +1000, Neil Brown wrote:
> > >  On 2.6.13-rc1 the same test takes just short on 1 minute and reports
> > >  slightly less than 2 M/Second.
> > 
> > That sounds like your drives have negotiated an asynchronous transfer
> > agreement.  Could you provide your dmesg to confirm that diagnosis?
> 
> Yes, that looks right.


I just noticed:


> From: James Bottomley <James.Bottomley@xxxxxxxxxxxx>
> To: Tony Vroon <chainsaw@xxxxxxxxxx>
> Cc: Linux Kernel <linux-kernel@xxxxxxxxxxxxxxx>,
>         SCSI Mailing List <linux-scsi@xxxxxxxxxxxxxxx>,
>         Andy Whitcroft <apw@xxxxxxxxxxxx>
> Subject: Re: aic7xxx regression occuring after 2.6.12 final
> Date: 	Sat, 02 Jul 2005 14:46:14 -0500

which had the following patch which fixes this problem nicely.  Sorry for the
extra noise.

(Thanks James)

NeilBrown


diff --git a/drivers/scsi/aic7xxx/aic7xxx_osm.c b/drivers/scsi/aic7xxx/aic7xxx_osm.c
--- a/drivers/scsi/aic7xxx/aic7xxx_osm.c
+++ b/drivers/scsi/aic7xxx/aic7xxx_osm.c
@@ -2633,6 +2633,11 @@ static void ahc_linux_set_dt(struct scsi
 	ahc_unlock(ahc, &flags);
 }
 
+#if 0
+/* FIXME: This code claims to support IU and QAS.  However, the actual
+ * sequencer code and aic7xxx_core have no support for these parameters and
+ * will get into a bad state if they're negotiated.  Do not enable this
+ * unless you know what you're doing */
 static void ahc_linux_set_qas(struct scsi_target *starget, int qas)
 {
 	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
@@ -2688,6 +2693,7 @@ static void ahc_linux_set_iu(struct scsi
 			 ppr_options, AHC_TRANS_GOAL, FALSE);
 	ahc_unlock(ahc, &flags);
 }
+#endif
 
 static struct spi_function_template ahc_linux_transport_functions = {
 	.set_offset	= ahc_linux_set_offset,
@@ -2698,10 +2704,12 @@ static struct spi_function_template ahc_
 	.show_width	= 1,
 	.set_dt		= ahc_linux_set_dt,
 	.show_dt	= 1,
+#if 0
 	.set_iu		= ahc_linux_set_iu,
 	.show_iu	= 1,
 	.set_qas	= ahc_linux_set_qas,
 	.show_qas	= 1,
+#endif
 };
 
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