change_queue_depth allows changing per-target queue depth via sysfs. It also allows the SCSI midlayer to ramp down the number of concurrent inflight requests in response to a SCSI BUSY status response and allows the midlayer to ramp the count back up to the device maximum when the BUSY condition has resolved. Signed-off-by: Venkatesh Srinivas <venkateshs@xxxxxxxxxx> --- drivers/scsi/virtio_scsi.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c index db3b494..6cd39cd 100644 --- a/drivers/scsi/virtio_scsi.c +++ b/drivers/scsi/virtio_scsi.c @@ -26,6 +26,7 @@ #include <scsi/scsi_host.h> #include <scsi/scsi_device.h> #include <scsi/scsi_cmnd.h> +#include <scsi/scsi_tcq.h> #define VIRTIO_SCSI_MEMPOOL_SZ 64 #define VIRTIO_SCSI_EVENT_LEN 8 @@ -633,6 +634,36 @@ static int virtscsi_device_reset(struct scsi_cmnd *sc) return virtscsi_tmf(vscsi, cmd); } +/** + * virtscsi_change_queue_depth() - Change a virtscsi target's queue depth + * @sdev: Virtscsi target whose queue depth to change + * @qdepth: New queue depth + * @reason: Reason for the queue depth change. + */ +static int virtscsi_change_queue_depth(struct scsi_device *sdev, + int qdepth, + int reason) +{ + struct Scsi_Host *shost = sdev->host; + int max_depth = shost->cmd_per_lun; + + switch (reason) { + case SCSI_QDEPTH_QFULL: /* Drop qdepth in response to BUSY state */ + scsi_track_queue_full(sdev, qdepth); + break; + case SCSI_QDEPTH_RAMP_UP: /* Raise qdepth after BUSY state resolved */ + case SCSI_QDEPTH_DEFAULT: /* Manual change via sysfs */ + scsi_adjust_queue_depth(sdev, + scsi_get_tag_type(sdev), + min(max_depth, qdepth)); + break; + default: + return -EOPNOTSUPP; + } + + return sdev->queue_depth; +} + static int virtscsi_abort(struct scsi_cmnd *sc) { struct virtio_scsi *vscsi = shost_priv(sc->device->host); @@ -684,6 +715,7 @@ static struct scsi_host_template virtscsi_host_template_single = { .proc_name = "virtio_scsi", .this_id = -1, .queuecommand = virtscsi_queuecommand_single, + .change_queue_depth = virtscsi_change_queue_depth, .eh_abort_handler = virtscsi_abort, .eh_device_reset_handler = virtscsi_device_reset, @@ -700,6 +732,7 @@ static struct scsi_host_template virtscsi_host_template_multi = { .proc_name = "virtio_scsi", .this_id = -1, .queuecommand = virtscsi_queuecommand_multi, + .change_queue_depth = virtscsi_change_queue_depth, .eh_abort_handler = virtscsi_abort, .eh_device_reset_handler = virtscsi_device_reset, -- 1.9.1.423.g4596e3a _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization