| Message ID | 1440679281-13234-23-git-send-email-hare@suse.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Aug 27, 2015 at 02:41:20PM +0200, Hannes Reinecke wrote: > Sending a 'REPORT TARGET PORT GROUP' command is a costly operation, > as the array has to gather information about all ports. > So instead of using RTPG to poll for a status update when a port > is in transitioning we should be sending a TEST UNIT READY, and > wait for the sense code to report success. The extra state variabe doesn't really help you as it might be stale just as quickly. But otherwise looks fine: Reviewed-by: Christoph Hellwig <hch@lst.de> -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, 2015-08-27 at 14:41 +0200, Hannes Reinecke wrote: > Sending a 'REPORT TARGET PORT GROUP' command is a costly operation, > as the array has to gather information about all ports. > So instead of using RTPG to poll for a status update when a port > is in transitioning we should be sending a TEST UNIT READY, and > wait for the sense code to report success. > > Signed-off-by: Hannes Reinecke <hare@suse.de> > --- > drivers/scsi/device_handler/scsi_dh_alua.c | 33 ++++++++++++++++++++++++++++++ > 1 file changed, 33 insertions(+) > > diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c > index 2fa985e..3c6b365 100644 > --- a/drivers/scsi/device_handler/scsi_dh_alua.c > +++ b/drivers/scsi/device_handler/scsi_dh_alua.c > @@ -467,6 +467,30 @@ static int alua_check_sense(struct scsi_device *sdev, > } > > /* > + * alua_tur - Send a TEST UNIT READY > + * @sdev: device to which the TEST UNIT READY command should be send > + * > + * Send a TEST UNIT READY to @sdev to figure out the device state > + * Returns SCSI_DH_RETRY if the sense code is NOT READY/ALUA TRANSITIONING, > + * SCSI_DH_OK if no error occured, and SCSI_DH_IO otherwise. > + */ > +static int alua_tur(struct scsi_device *sdev) > +{ > + struct scsi_sense_hdr sense_hdr; > + int retval; > + > + retval = scsi_test_unit_ready(sdev, ALUA_FAILOVER_TIMEOUT * HZ, > + ALUA_FAILOVER_RETRIES, &sense_hdr); > + if (sense_hdr.sense_key == NOT_READY && > + sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a) > + return SCSI_DH_RETRY; > + else if (retval) > + return SCSI_DH_IO; > + else > + return SCSI_DH_OK; > +} > + > +/* > * alua_rtpg - Evaluate REPORT TARGET GROUP STATES > * @sdev: the device to be evaluated. > * > @@ -725,7 +749,16 @@ static void alua_rtpg_work(struct work_struct *work) > return; > } > if (pg->flags & ALUA_PG_RUN_RTPG) { > + int state = pg->state; > spin_unlock_irqrestore(&pg->rtpg_lock, flags); > + if (state == TPGS_STATE_TRANSITIONING) { > + if (alua_tur(sdev) == SCSI_DH_RETRY) { > + queue_delayed_work(pg->work_q, &pg->rtpg_work, > + pg->interval * HZ); > + return; > + } > + /* Send RTPG on failure or if TUR indicates SUCCESS */ > + } > err = alua_rtpg(sdev, pg); > if (err == SCSI_DH_RETRY) { > queue_delayed_work(pg->work_q, &pg->rtpg_work, Reviewed-by: Ewan D. Milne <emilne@redhat.com> -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c index 2fa985e..3c6b365 100644 --- a/drivers/scsi/device_handler/scsi_dh_alua.c +++ b/drivers/scsi/device_handler/scsi_dh_alua.c @@ -467,6 +467,30 @@ static int alua_check_sense(struct scsi_device *sdev, } /* + * alua_tur - Send a TEST UNIT READY + * @sdev: device to which the TEST UNIT READY command should be send + * + * Send a TEST UNIT READY to @sdev to figure out the device state + * Returns SCSI_DH_RETRY if the sense code is NOT READY/ALUA TRANSITIONING, + * SCSI_DH_OK if no error occured, and SCSI_DH_IO otherwise. + */ +static int alua_tur(struct scsi_device *sdev) +{ + struct scsi_sense_hdr sense_hdr; + int retval; + + retval = scsi_test_unit_ready(sdev, ALUA_FAILOVER_TIMEOUT * HZ, + ALUA_FAILOVER_RETRIES, &sense_hdr); + if (sense_hdr.sense_key == NOT_READY && + sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a) + return SCSI_DH_RETRY; + else if (retval) + return SCSI_DH_IO; + else + return SCSI_DH_OK; +} + +/* * alua_rtpg - Evaluate REPORT TARGET GROUP STATES * @sdev: the device to be evaluated. * @@ -725,7 +749,16 @@ static void alua_rtpg_work(struct work_struct *work) return; } if (pg->flags & ALUA_PG_RUN_RTPG) { + int state = pg->state; spin_unlock_irqrestore(&pg->rtpg_lock, flags); + if (state == TPGS_STATE_TRANSITIONING) { + if (alua_tur(sdev) == SCSI_DH_RETRY) { + queue_delayed_work(pg->work_q, &pg->rtpg_work, + pg->interval * HZ); + return; + } + /* Send RTPG on failure or if TUR indicates SUCCESS */ + } err = alua_rtpg(sdev, pg); if (err == SCSI_DH_RETRY) { queue_delayed_work(pg->work_q, &pg->rtpg_work,
Sending a 'REPORT TARGET PORT GROUP' command is a costly operation, as the array has to gather information about all ports. So instead of using RTPG to poll for a status update when a port is in transitioning we should be sending a TEST UNIT READY, and wait for the sense code to report success. Signed-off-by: Hannes Reinecke <hare@suse.de> --- drivers/scsi/device_handler/scsi_dh_alua.c | 33 ++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+)