Hi,
Tagged queueing feature of a VMware virtual disk connected with SCSI
has been disabled since the cam quirk was added.
# this quirk is needed to find the drive by SCSI HA.
I modified this quirk to allow tagged queueing while finding out causes
of low disk performance.
This modification improve the throughput of the disk I/O on VMware ESX
Server 3, at least. (4MBps -> 18Mbps, by some easy measurements using dd).
I think following modification to be applicable to RELENG_[456] and MAIN.
I applied this patch to my RELENG_5 (virtual) box and do 'make -j4
buildworld' now and at present, the problem has not occurred.
--- sys/cam/cam_xpt.c.orig Fri Sep 8 18:10:14 2006
+++ sys/cam/cam_xpt.c Fri Sep 8 17:43:57 2006
@@ -359,7 +359,7 @@
{
/* Does not support other than LUN 0 */
{ T_DIRECT, SIP_MEDIA_FIXED, "VMware*", "*",
"*" },
- CAM_QUIRK_NOLUNS, /*mintags*/0, /*maxtags*/0
+ CAM_QUIRK_NOLUNS, /*mintags*/2, /*maxtags*/255
},
thank you.
--
Shunsuke SHINOMIYA <shino@fornext.org>