Christoph,
> Apparently the optimal IO sizes reported by the ASMedia ASM105x is
> bogus.
>
> Not sure whether the kernel provides means to work around quirks at
> this level, but in case it does it would be nice if some reasonable
> value could be used to override the opt io of 33553920.
We have had devices with bogus values before. The problem in this case
is that 32M is a large, but not entirely unreasonable, stripe I/O width
for a storage array.
Does this fix it for you?
--
Martin K. Petersen Oracle Linux Engineering
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 9421d9877730..4e2fdfa870c2 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3126,12 +3126,13 @@ static int sd_revalidate_disk(struct gendisk *disk)
/*
* Determine the device's preferred I/O size for reads and writes
- * unless the reported value is unreasonably small, large, or
- * garbage.
+ * unless the reported value is unreasonably small, large, not a
+ * multiple of the physical block size, or simply garbage.
*/
if (sdkp->opt_xfer_blocks &&
sdkp->opt_xfer_blocks <= dev_max &&
sdkp->opt_xfer_blocks <= SD_DEF_XFER_BLOCKS &&
+ sdkp->opt_xfer_blocks & sdkp->physical_block_size - 1 != 0 &&
logical_to_bytes(sdp, sdkp->opt_xfer_blocks) >= PAGE_SIZE) {
q->limits.io_opt = logical_to_bytes(sdp, sdkp->opt_xfer_blocks);
rw_max = logical_to_sectors(sdp, sdkp->opt_xfer_blocks);
