From: Long Li <lon...@microsoft.com>
Properly set SRB flags when hosting device supports tagged queuing. This patch
improves the performance on Fiber Channel disks.
---
drivers/scsi/storvsc_drv.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index 8ccfc9e..a8f3e4c 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -136,6 +136,8 @@ struct hv_fc_wwn_packet {
#define SRB_FLAGS_PORT_DRIVER_RESERVED 0x0F000000
#define SRB_FLAGS_CLASS_DRIVER_RESERVED 0xF0000000
+#define SP_UNTAGGED ((unsigned char) ~0)
+#define SRB_SIMPLE_TAG_REQUEST 0x20
/*
* Platform neutral description of a scsi request -
@@ -1451,6 +1453,12 @@ static int storvsc_queuecommand(struct Scsi_Host *host,
struct scsi_cmnd *scmnd)
vm_srb->win8_extension.srb_flags |=
SRB_FLAGS_DISABLE_SYNCH_TRANSFER;
+ if(scmnd->device->tagged_supported) {
+ vm_srb->win8_extension.srb_flags |=
(SRB_FLAGS_QUEUE_ACTION_ENABLE | SRB_FLAGS_NO_QUEUE_FREEZE);
+ vm_srb->win8_extension.queue_tag = SP_UNTAGGED;
+ vm_srb->win8_extension.queue_action = SRB_SIMPLE_TAG_REQUEST;
+ }
+
/* Build the SRB */
switch (scmnd->sc_data_direction) {
case DMA_TO_DEVICE:
--
1.8.5.6
--
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