5.3-RELEASE: WARNING - WRITE_DMA interrupt timout

[Zoltan Frombach]

I will apply this patch first thing tomorrow. But I don't see how will I see 
any difference? Does it put something into a log file? Shouldn't it?

Zoltan

Poul-Henning Kamp wrote:
> In message <4195E1FF.5090906 at DeepCore.dk>, 
> =?ISO-8859-1?Q?S=F8ren_Schmidt?= wri
> tes:
>
>
>>>>Timeout is 5 secs, which is a pretty long time in this context IMHO..
>>>
>>>Five seconds counted from when ?
>>
>>Now thats the nasty part :)
>>ATA starts the timeout when the request is issued to the device, so 
>>theoretically the disk could take 4.9999 secs to complete the request and 
>>then the timeout fires before the taskqueue gets its chance at it, but 
>>IMHO thats pretty unlikely...
>
> I find that far more likely than kernel threads being stalled for that
> long.  ATA disks doing bad-block stuff takes several seconds on some
> of the disks I've had my hands on.
>
>>Anyhow, I can just remove the warning from ATA if that makes anyone happy, 
>>since its just a warning and ATA doesn't do anything with it at all.
>>However, IMNHO this points at a problem somewhere that we should better 
>>understand and fix instead.
>
> I would prefer you reset the timer to five seconds in your interrupt
> routine so we can see exactly on which side of that the time is spent.

It would be even better to time how long both ops take and be able to
get that via a sysctl or something (I have that on my TODO list but its
loooong :) ).

Anyhow resetting it is easy (patch against 5.3R):

Index: ata-queue.c
===================================================================
RCS file: /home/ncvs/src/sys/dev/ata/ata-queue.c,v
retrieving revision 1.32.2.5
diff -u -r1.32.2.5 ata-queue.c
--- ata-queue.c 24 Oct 2004 09:27:37 -0000      1.32.2.5
+++ ata-queue.c 13 Nov 2004 10:44:40 -0000
@@ -216,6 +216,9 @@
         ata_completed(request, 0);
      }
      else {
+       if (!dumping)
+           callout_reset(&request->callout, request->timeout * hz,
+                         (timeout_t*)ata_timeout, request);
         if (request->bio && !(request->flags & ATA_R_TIMEOUT)) {
             ATA_DEBUG_RQ(request, "finish bio_taskqueue");
             bio_taskqueue(request->bio, (bio_task_t *)ata_completed,
request);

-- 

-Søren