Re: SCSI I/O performance problems when CONFIG_HIGHIO is off

From: Stephen Lord (lord@sgi.com)
Date: Mon Nov 18 2002 - 09:05:13 EST

On Mon, 2002-11-18 at 06:05, Jens Axboe wrote:

>
> Steve,
>
> Something isn't quite making sense. If we go over every single instance
> of checking ->highmem_io, they all look sane (ie checking on non-highmem
> setup must yield 0). So that part looks good.
>
> However, I think a typo snuck in there, in exactly the spot you pasted
> above. Could you try 2.4.20-rc2 with this patch applied?
>
> ===== drivers/scsi/scsi_merge.c 1.9 vs edited =====
> --- 1.9/drivers/scsi/scsi_merge.c Mon Sep 16 09:25:10 2002
> +++ edited/drivers/scsi/scsi_merge.c Mon Nov 18 13:04:41 2002
> @@ -835,7 +835,7 @@
> * case.
> */
> if (count == 1 && !SCpnt->host->highmem_io) {
> - this_count = req->current_nr_sectors;
> + this_count = req->nr_sectors;
> goto single_segment;
> }

That looks like it does it, performance is pretty much what I was
getting with HIGHIO on.

Thanks

  Steve
  

-- 
Stephen  Lord <lord@sgi.com>

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This archive was generated by hypermail 2b29 : Sat Nov 23 2002 - 22:00:22 EST