[PATCH 1/3] storvsc: use tagged SRB requests if supported by the device

[Johannes Thumshirn]

On Tue, Sep 06, 2016 at 02:25:41PM -0700, Long Li wrote:
> From: Long Li <longli at microsoft.com>
> 
> Properly set SRB flags when hosting device supports tagged queuing. This patch improves the performance on Fiber Channel disks.

ENOSIGNEDOFF and please use checkpatch.pl on the patch. 

> 
> ---
>  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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-- 
Johannes Thumshirn                                          Storage
jthumshirn at suse.de                                +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
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