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
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