* Slower write performance in RHEL6
@ 2011-07-26 11:22 Li Liu
2011-07-26 11:38 ` Ric Wheeler
0 siblings, 1 reply; 2+ messages in thread
From: Li Liu @ 2011-07-26 11:22 UTC (permalink / raw)
To: linux-scsi
Dear all,
In RHEL6(linux-2.6.32-71.el6), I added some codes in
scsi_softirq_done to check the result of execute scsi commands:
WRITE_6, WRITE_10, WRITE_12, WRITE_16 when I executed "dd if=/dev/zero
of=/dev/xda bs=64k count=10000". I found a lot of write error messages
in scsi_softirq_done, the disposition(variable) was ADD_TO_MLQUEUE and
the speed was 78MB/s.
Then I changed MPT_SCSI_CMD_PER_DEV_HIGH from 64 to 32 in
mptscsih_change_queue_depth, the speed was 140MB/s and none error
messages.
* /dev/xda is a scsi disk.
* the scsi host is LSI1064E.
* MPT_SCSI_CMD_PER_DEV_HIGH will be assigned to blk_queue_tag->max_depth.
My questions are:
Is the TCQ depth limited by hard disk, how can I get the limited?
Why the speed was drop to 78MB/s when MPT_SCSI_CMD_PER_DEV_HIGH was 64?
Could I change MPT_SCSI_CMD_PER_DEV_HIGH to 32 or 16 or 8, Will it
cause any problem?
Thanks for any ideas.
Thanks,
Alex Liu
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Slower write performance in RHEL6
2011-07-26 11:22 Slower write performance in RHEL6 Li Liu
@ 2011-07-26 11:38 ` Ric Wheeler
0 siblings, 0 replies; 2+ messages in thread
From: Ric Wheeler @ 2011-07-26 11:38 UTC (permalink / raw)
To: Li Liu; +Cc: linux-scsi
On 07/26/2011 07:22 AM, Li Liu wrote:
> Dear all,
>
> In RHEL6(linux-2.6.32-71.el6), I added some codes in
> scsi_softirq_done to check the result of execute scsi commands:
> WRITE_6, WRITE_10, WRITE_12, WRITE_16 when I executed "dd if=/dev/zero
> of=/dev/xda bs=64k count=10000". I found a lot of write error messages
> in scsi_softirq_done, the disposition(variable) was ADD_TO_MLQUEUE and
> the speed was 78MB/s.
> Then I changed MPT_SCSI_CMD_PER_DEV_HIGH from 64 to 32 in
> mptscsih_change_queue_depth, the speed was 140MB/s and none error
> messages.
> * /dev/xda is a scsi disk.
> * the scsi host is LSI1064E.
> * MPT_SCSI_CMD_PER_DEV_HIGH will be assigned to blk_queue_tag->max_depth.
>
> My questions are:
> Is the TCQ depth limited by hard disk, how can I get the limited?
> Why the speed was drop to 78MB/s when MPT_SCSI_CMD_PER_DEV_HIGH was 64?
> Could I change MPT_SCSI_CMD_PER_DEV_HIGH to 32 or 16 or 8, Will it
> cause any problem?
>
> Thanks for any ideas.
>
> Thanks,
> Alex Liu
When you have a vendor specific issues, it is probably best to raise a ticket
with the vendor's support organization....
Thanks!
Ric
^ permalink raw reply [flat|nested] 2+ messages in thread
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