* [PATCH] scsi: sd: Add a comment about limiting max_sectors to shost optimal limit
@ 2022-07-19 9:51 John Garry
2022-07-19 10:06 ` Damien Le Moal
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: John Garry @ 2022-07-19 9:51 UTC (permalink / raw)
To: jejb, martin.petersen, hch, damien.lemoal
Cc: linux-scsi, linux-kernel, iommu, John Garry
Add a comment about limiting the default the SCSI disk request_queue
max_sectors initial value to that of the SCSI host optimal sectors limit.
Suggested-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: John Garry <john.garry@huawei.com>
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 3eaee1f7aaca..ed9f43f9512e 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3296,6 +3296,11 @@ static int sd_revalidate_disk(struct gendisk *disk)
(sector_t)BLK_DEF_MAX_SECTORS);
}
+ /*
+ * Limit default to SCSI host optimal sector limit if set. There may be
+ * an impact on performance for when the size of a request exceeds this
+ * host limit.
+ */
rw_max = min_not_zero(rw_max, sdp->host->opt_sectors);
/* Do not exceed controller limit */
--
2.35.3
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH] scsi: sd: Add a comment about limiting max_sectors to shost optimal limit
2022-07-19 9:51 [PATCH] scsi: sd: Add a comment about limiting max_sectors to shost optimal limit John Garry
@ 2022-07-19 10:06 ` Damien Le Moal
2022-07-20 1:21 ` Martin K. Petersen
2022-07-22 15:15 ` Christoph Hellwig
2 siblings, 0 replies; 4+ messages in thread
From: Damien Le Moal @ 2022-07-19 10:06 UTC (permalink / raw)
To: John Garry, jejb, martin.petersen, hch; +Cc: linux-scsi, linux-kernel, iommu
On 7/19/22 18:51, John Garry wrote:
> Add a comment about limiting the default the SCSI disk request_queue
> max_sectors initial value to that of the SCSI host optimal sectors limit.
>
> Suggested-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
> Signed-off-by: John Garry <john.garry@huawei.com>
>
> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
> index 3eaee1f7aaca..ed9f43f9512e 100644
> --- a/drivers/scsi/sd.c
> +++ b/drivers/scsi/sd.c
> @@ -3296,6 +3296,11 @@ static int sd_revalidate_disk(struct gendisk *disk)
> (sector_t)BLK_DEF_MAX_SECTORS);
> }
>
> + /*
> + * Limit default to SCSI host optimal sector limit if set. There may be
> + * an impact on performance for when the size of a request exceeds this
> + * host limit.
> + */
> rw_max = min_not_zero(rw_max, sdp->host->opt_sectors);
>
> /* Do not exceed controller limit */
Looks good.
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
--
Damien Le Moal
Western Digital Research
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] scsi: sd: Add a comment about limiting max_sectors to shost optimal limit
2022-07-19 9:51 [PATCH] scsi: sd: Add a comment about limiting max_sectors to shost optimal limit John Garry
2022-07-19 10:06 ` Damien Le Moal
@ 2022-07-20 1:21 ` Martin K. Petersen
2022-07-22 15:15 ` Christoph Hellwig
2 siblings, 0 replies; 4+ messages in thread
From: Martin K. Petersen @ 2022-07-20 1:21 UTC (permalink / raw)
To: John Garry
Cc: jejb, martin.petersen, hch, damien.lemoal, linux-scsi,
linux-kernel, iommu
John,
> Add a comment about limiting the default the SCSI disk request_queue
> max_sectors initial value to that of the SCSI host optimal sectors limit.
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
--
Martin K. Petersen Oracle Linux Engineering
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] scsi: sd: Add a comment about limiting max_sectors to shost optimal limit
2022-07-19 9:51 [PATCH] scsi: sd: Add a comment about limiting max_sectors to shost optimal limit John Garry
2022-07-19 10:06 ` Damien Le Moal
2022-07-20 1:21 ` Martin K. Petersen
@ 2022-07-22 15:15 ` Christoph Hellwig
2 siblings, 0 replies; 4+ messages in thread
From: Christoph Hellwig @ 2022-07-22 15:15 UTC (permalink / raw)
To: John Garry
Cc: jejb, martin.petersen, hch, damien.lemoal, linux-scsi,
linux-kernel, iommu
Thanks, applied.
^ permalink raw reply [flat|nested] 4+ messages in thread
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2022-07-19 9:51 [PATCH] scsi: sd: Add a comment about limiting max_sectors to shost optimal limit John Garry
2022-07-19 10:06 ` Damien Le Moal
2022-07-20 1:21 ` Martin K. Petersen
2022-07-22 15:15 ` Christoph Hellwig
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