* [PATCH 1/3 V2] alua: implement 'implied transition timeout'
2012-05-18 18:08 [PATCH 0/3 V2] alua updates Rob Evers
@ 2012-05-18 18:08 ` Rob Evers
2012-05-18 18:17 ` Moger, Babu
2012-05-18 18:08 ` [PATCH 2/3 V2] alua: retry alua rtpg extended header for illegal request response Rob Evers
` (2 subsequent siblings)
3 siblings, 1 reply; 8+ messages in thread
From: Rob Evers @ 2012-05-18 18:08 UTC (permalink / raw)
To: linux-scsi
During alua transitions, an array can return transitioning
status in response to rtpg requests. These requests get
retried for a maximum of 60 seconds by default before timing
out. Sometimes this timeout isn't sufficient to allow the
array to complete the transition. T10-spc4 addresses this
under 'Report Target Port Groups' command.
This update retrieves the timeout value from the storage
array if available and retries the transitioning rtpgs
for up to the 'implied transitioning timeout' value
Signed-off-by: Rob Evers <revers@redhat.com>
---
drivers/scsi/device_handler/scsi_dh_alua.c | 41 ++++++++++++++++++++++++---
include/scsi/scsi.h | 2 +
2 files changed, 38 insertions(+), 5 deletions(-)
diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
index 04c5cea..6a7efd3 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -46,13 +46,16 @@
#define TPGS_SUPPORT_OFFLINE 0x40
#define TPGS_SUPPORT_TRANSITION 0x80
+#define RTPG_FMT_MASK 0x70
+#define RTPG_FMT_EXT_HDR 0x10
+
#define TPGS_MODE_UNINITIALIZED -1
#define TPGS_MODE_NONE 0x0
#define TPGS_MODE_IMPLICIT 0x1
#define TPGS_MODE_EXPLICIT 0x2
#define ALUA_INQUIRY_SIZE 36
-#define ALUA_FAILOVER_TIMEOUT (60 * HZ)
+#define ALUA_FAILOVER_TIMEOUT 60
#define ALUA_FAILOVER_RETRIES 5
struct alua_dh_data {
@@ -63,6 +66,7 @@ struct alua_dh_data {
unsigned char inq[ALUA_INQUIRY_SIZE];
unsigned char *buff;
int bufflen;
+ unsigned char transition_tmo;
unsigned char sense[SCSI_SENSE_BUFFERSIZE];
int senselen;
struct scsi_device *sdev;
@@ -123,7 +127,7 @@ static struct request *get_alua_req(struct scsi_device *sdev,
rq->cmd_flags |= REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
REQ_FAILFAST_DRIVER;
rq->retries = ALUA_FAILOVER_RETRIES;
- rq->timeout = ALUA_FAILOVER_TIMEOUT;
+ rq->timeout = ALUA_FAILOVER_TIMEOUT * HZ;
return rq;
}
@@ -180,7 +184,7 @@ static unsigned submit_rtpg(struct scsi_device *sdev, struct alua_dh_data *h)
/* Prepare the command. */
rq->cmd[0] = MAINTENANCE_IN;
- rq->cmd[1] = MI_REPORT_TARGET_PGS;
+ rq->cmd[1] = MI_REPORT_TARGET_PGS | MI_EXT_HDR_PARAM_FMT;
rq->cmd[6] = (h->bufflen >> 24) & 0xff;
rq->cmd[7] = (h->bufflen >> 16) & 0xff;
rq->cmd[8] = (h->bufflen >> 8) & 0xff;
@@ -514,8 +518,14 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h)
unsigned char *ucp;
unsigned err;
unsigned long expiry, interval = 1000;
+ unsigned int tpg_desc_tbl_off;
+ unsigned char orig_transition_tmo;
+
+ if (!h->transition_tmo)
+ expiry = round_jiffies_up(jiffies + ALUA_FAILOVER_TIMEOUT * HZ);
+ else
+ expiry = round_jiffies_up(jiffies + h->transition_tmo * HZ);
- expiry = round_jiffies_up(jiffies + ALUA_FAILOVER_TIMEOUT);
retry:
err = submit_rtpg(sdev, h);
@@ -551,7 +561,28 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h)
goto retry;
}
- for (k = 4, ucp = h->buff + 4; k < len; k += off, ucp += off) {
+ orig_transition_tmo = h->transition_tmo;
+ if ((h->buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR && h->buff[5] != 0)
+ h->transition_tmo = h->buff[5];
+ else
+ h->transition_tmo = ALUA_FAILOVER_TIMEOUT;
+
+ if (orig_transition_tmo != h->transition_tmo) {
+ sdev_printk(KERN_INFO, sdev,
+ "%s: transition timeout set to %d seconds\n",
+ ALUA_DH_NAME, h->transition_tmo);
+ expiry = jiffies + h->transition_tmo * HZ;
+ }
+
+ if ((h->buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR)
+ tpg_desc_tbl_off = 8;
+ else
+ tpg_desc_tbl_off = 4;
+
+ for (k = tpg_desc_tbl_off, ucp = h->buff + tpg_desc_tbl_off;
+ k < len;
+ k += off, ucp += off) {
+
if (h->group_id == (ucp[2] << 8) + ucp[3]) {
h->state = ucp[0] & 0x0f;
valid_states = ucp[1];
diff --git a/include/scsi/scsi.h b/include/scsi/scsi.h
index f34a5a8..c6f0974 100644
--- a/include/scsi/scsi.h
+++ b/include/scsi/scsi.h
@@ -161,6 +161,8 @@ struct scsi_cmnd;
#define MI_REPORT_PRIORITY 0x0e
#define MI_REPORT_TIMESTAMP 0x0f
#define MI_MANAGEMENT_PROTOCOL_IN 0x10
+/* value for MI_REPORT_TARGET_PGS ext header */
+#define MI_EXT_HDR_PARAM_FMT 0x20
/* values for maintenance out */
#define MO_SET_IDENTIFYING_INFORMATION 0x06
#define MO_SET_TARGET_PGS 0x0a
--
1.7.7.2
^ permalink raw reply related [flat|nested] 8+ messages in thread* RE: [PATCH 1/3 V2] alua: implement 'implied transition timeout'
2012-05-18 18:08 ` [PATCH 1/3 V2] alua: implement 'implied transition timeout' Rob Evers
@ 2012-05-18 18:17 ` Moger, Babu
0 siblings, 0 replies; 8+ messages in thread
From: Moger, Babu @ 2012-05-18 18:17 UTC (permalink / raw)
To: Rob Evers, linux-scsi@vger.kernel.org
> -----Original Message-----
> From: linux-scsi-owner@vger.kernel.org [mailto:linux-scsi-
> owner@vger.kernel.org] On Behalf Of Rob Evers
> Sent: Friday, May 18, 2012 1:09 PM
> To: linux-scsi@vger.kernel.org
> Subject: [PATCH 1/3 V2] alua: implement 'implied transition timeout'
>
> During alua transitions, an array can return transitioning
> status in response to rtpg requests. These requests get
> retried for a maximum of 60 seconds by default before timing
> out. Sometimes this timeout isn't sufficient to allow the
> array to complete the transition. T10-spc4 addresses this
> under 'Report Target Port Groups' command.
>
> This update retrieves the timeout value from the storage
> array if available and retries the transitioning rtpgs
> for up to the 'implied transitioning timeout' value
>
> Signed-off-by: Rob Evers <revers@redhat.com>
Reviewed-by: Babu Moger <babu.moger@netapp.com>
> ---
> drivers/scsi/device_handler/scsi_dh_alua.c | 41
> ++++++++++++++++++++++++---
> include/scsi/scsi.h | 2 +
> 2 files changed, 38 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c
> b/drivers/scsi/device_handler/scsi_dh_alua.c
> index 04c5cea..6a7efd3 100644
> --- a/drivers/scsi/device_handler/scsi_dh_alua.c
> +++ b/drivers/scsi/device_handler/scsi_dh_alua.c
> @@ -46,13 +46,16 @@
> #define TPGS_SUPPORT_OFFLINE 0x40
> #define TPGS_SUPPORT_TRANSITION 0x80
>
> +#define RTPG_FMT_MASK 0x70
> +#define RTPG_FMT_EXT_HDR 0x10
> +
> #define TPGS_MODE_UNINITIALIZED -1
> #define TPGS_MODE_NONE 0x0
> #define TPGS_MODE_IMPLICIT 0x1
> #define TPGS_MODE_EXPLICIT 0x2
>
> #define ALUA_INQUIRY_SIZE 36
> -#define ALUA_FAILOVER_TIMEOUT (60 * HZ)
> +#define ALUA_FAILOVER_TIMEOUT 60
> #define ALUA_FAILOVER_RETRIES 5
>
> struct alua_dh_data {
> @@ -63,6 +66,7 @@ struct alua_dh_data {
> unsigned char inq[ALUA_INQUIRY_SIZE];
> unsigned char *buff;
> int bufflen;
> + unsigned char transition_tmo;
> unsigned char sense[SCSI_SENSE_BUFFERSIZE];
> int senselen;
> struct scsi_device *sdev;
> @@ -123,7 +127,7 @@ static struct request *get_alua_req(struct scsi_device
> *sdev,
> rq->cmd_flags |= REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT
> |
> REQ_FAILFAST_DRIVER;
> rq->retries = ALUA_FAILOVER_RETRIES;
> - rq->timeout = ALUA_FAILOVER_TIMEOUT;
> + rq->timeout = ALUA_FAILOVER_TIMEOUT * HZ;
>
> return rq;
> }
> @@ -180,7 +184,7 @@ static unsigned submit_rtpg(struct scsi_device *sdev,
> struct alua_dh_data *h)
>
> /* Prepare the command. */
> rq->cmd[0] = MAINTENANCE_IN;
> - rq->cmd[1] = MI_REPORT_TARGET_PGS;
> + rq->cmd[1] = MI_REPORT_TARGET_PGS |
> MI_EXT_HDR_PARAM_FMT;
> rq->cmd[6] = (h->bufflen >> 24) & 0xff;
> rq->cmd[7] = (h->bufflen >> 16) & 0xff;
> rq->cmd[8] = (h->bufflen >> 8) & 0xff;
> @@ -514,8 +518,14 @@ static int alua_rtpg(struct scsi_device *sdev, struct
> alua_dh_data *h)
> unsigned char *ucp;
> unsigned err;
> unsigned long expiry, interval = 1000;
> + unsigned int tpg_desc_tbl_off;
> + unsigned char orig_transition_tmo;
> +
> + if (!h->transition_tmo)
> + expiry = round_jiffies_up(jiffies +
> ALUA_FAILOVER_TIMEOUT * HZ);
> + else
> + expiry = round_jiffies_up(jiffies + h->transition_tmo * HZ);
>
> - expiry = round_jiffies_up(jiffies + ALUA_FAILOVER_TIMEOUT);
> retry:
> err = submit_rtpg(sdev, h);
>
> @@ -551,7 +561,28 @@ static int alua_rtpg(struct scsi_device *sdev, struct
> alua_dh_data *h)
> goto retry;
> }
>
> - for (k = 4, ucp = h->buff + 4; k < len; k += off, ucp += off) {
> + orig_transition_tmo = h->transition_tmo;
> + if ((h->buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR && h-
> >buff[5] != 0)
> + h->transition_tmo = h->buff[5];
> + else
> + h->transition_tmo = ALUA_FAILOVER_TIMEOUT;
> +
> + if (orig_transition_tmo != h->transition_tmo) {
> + sdev_printk(KERN_INFO, sdev,
> + "%s: transition timeout set to %d seconds\n",
> + ALUA_DH_NAME, h->transition_tmo);
> + expiry = jiffies + h->transition_tmo * HZ;
> + }
> +
> + if ((h->buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR)
> + tpg_desc_tbl_off = 8;
> + else
> + tpg_desc_tbl_off = 4;
> +
> + for (k = tpg_desc_tbl_off, ucp = h->buff + tpg_desc_tbl_off;
> + k < len;
> + k += off, ucp += off) {
> +
> if (h->group_id == (ucp[2] << 8) + ucp[3]) {
> h->state = ucp[0] & 0x0f;
> valid_states = ucp[1];
> diff --git a/include/scsi/scsi.h b/include/scsi/scsi.h
> index f34a5a8..c6f0974 100644
> --- a/include/scsi/scsi.h
> +++ b/include/scsi/scsi.h
> @@ -161,6 +161,8 @@ struct scsi_cmnd;
> #define MI_REPORT_PRIORITY 0x0e
> #define MI_REPORT_TIMESTAMP 0x0f
> #define MI_MANAGEMENT_PROTOCOL_IN 0x10
> +/* value for MI_REPORT_TARGET_PGS ext header */
> +#define MI_EXT_HDR_PARAM_FMT 0x20
> /* values for maintenance out */
> #define MO_SET_IDENTIFYING_INFORMATION 0x06
> #define MO_SET_TARGET_PGS 0x0a
> --
> 1.7.7.2
>
> --
> 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
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH 2/3 V2] alua: retry alua rtpg extended header for illegal request response
2012-05-18 18:08 [PATCH 0/3 V2] alua updates Rob Evers
2012-05-18 18:08 ` [PATCH 1/3 V2] alua: implement 'implied transition timeout' Rob Evers
@ 2012-05-18 18:08 ` Rob Evers
2012-05-18 18:19 ` Moger, Babu
2012-05-18 18:08 ` [PATCH 3/3 V2] alua: backoff alua rtpg retry linearly vs. geometrically Rob Evers
2012-06-05 16:38 ` [PATCH 0/3 V2] alua updates Rob Evers
3 siblings, 1 reply; 8+ messages in thread
From: Rob Evers @ 2012-05-18 18:08 UTC (permalink / raw)
To: linux-scsi
Some storage arrays are known to return 'illegal request'
when an rtpg extended header request is made. T10 says the
array should ignore the bit, and return the non-extended
rtpg as the array doesn't support the request. Working
around this by retrying the rtpg request without the extended
header bit set when the extended rtpg request results in
illegal request.
Signed-off-by: Rob Evers <revers@redhat.com>
---
drivers/scsi/device_handler/scsi_dh_alua.c | 26 +++++++++++++++++++++++---
1 files changed, 23 insertions(+), 3 deletions(-)
diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
index 6a7efd3..51d8cf6 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -173,7 +173,8 @@ done:
* submit_rtpg - Issue a REPORT TARGET GROUP STATES command
* @sdev: sdev the command should be sent to
*/
-static unsigned submit_rtpg(struct scsi_device *sdev, struct alua_dh_data *h)
+static unsigned submit_rtpg(struct scsi_device *sdev, struct alua_dh_data *h,
+ bool rtpg_ext_hdr_req)
{
struct request *rq;
int err = SCSI_DH_RES_TEMP_UNAVAIL;
@@ -184,7 +185,10 @@ static unsigned submit_rtpg(struct scsi_device *sdev, struct alua_dh_data *h)
/* Prepare the command. */
rq->cmd[0] = MAINTENANCE_IN;
- rq->cmd[1] = MI_REPORT_TARGET_PGS | MI_EXT_HDR_PARAM_FMT;
+ if (rtpg_ext_hdr_req)
+ rq->cmd[1] = MI_REPORT_TARGET_PGS | MI_EXT_HDR_PARAM_FMT;
+ else
+ rq->cmd[1] = MI_REPORT_TARGET_PGS;
rq->cmd[6] = (h->bufflen >> 24) & 0xff;
rq->cmd[7] = (h->bufflen >> 16) & 0xff;
rq->cmd[8] = (h->bufflen >> 8) & 0xff;
@@ -517,6 +521,7 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h)
int len, k, off, valid_states = 0;
unsigned char *ucp;
unsigned err;
+ bool rtpg_ext_hdr_req = 1;
unsigned long expiry, interval = 1000;
unsigned int tpg_desc_tbl_off;
unsigned char orig_transition_tmo;
@@ -527,7 +532,7 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h)
expiry = round_jiffies_up(jiffies + h->transition_tmo * HZ);
retry:
- err = submit_rtpg(sdev, h);
+ err = submit_rtpg(sdev, h, rtpg_ext_hdr_req);
if (err == SCSI_DH_IO && h->senselen > 0) {
err = scsi_normalize_sense(h->sense, SCSI_SENSE_BUFFERSIZE,
@@ -535,6 +540,21 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h)
if (!err)
return SCSI_DH_IO;
+ /*
+ * submit_rtpg() has failed on existing arrays
+ * when requesting extended header info, and
+ * the array doesn't support extended headers,
+ * even though it shouldn't according to T10.
+ * The retry without rtpg_ext_hdr_req set
+ * handles this.
+ */
+ if (rtpg_ext_hdr_req == 1 &&
+ sense_hdr.sense_key == ILLEGAL_REQUEST &&
+ sense_hdr.asc == 0x24 && sense_hdr.ascq == 0) {
+ rtpg_ext_hdr_req = 0;
+ goto retry;
+ }
+
err = alua_check_sense(sdev, &sense_hdr);
if (err == ADD_TO_MLQUEUE && time_before(jiffies, expiry))
goto retry;
--
1.7.7.2
^ permalink raw reply related [flat|nested] 8+ messages in thread* RE: [PATCH 2/3 V2] alua: retry alua rtpg extended header for illegal request response
2012-05-18 18:08 ` [PATCH 2/3 V2] alua: retry alua rtpg extended header for illegal request response Rob Evers
@ 2012-05-18 18:19 ` Moger, Babu
0 siblings, 0 replies; 8+ messages in thread
From: Moger, Babu @ 2012-05-18 18:19 UTC (permalink / raw)
To: Rob Evers, linux-scsi@vger.kernel.org
> -----Original Message-----
> From: linux-scsi-owner@vger.kernel.org [mailto:linux-scsi-
> owner@vger.kernel.org] On Behalf Of Rob Evers
> Sent: Friday, May 18, 2012 1:09 PM
> To: linux-scsi@vger.kernel.org
> Subject: [PATCH 2/3 V2] alua: retry alua rtpg extended header for illegal
> request response
>
> Some storage arrays are known to return 'illegal request'
> when an rtpg extended header request is made. T10 says the
> array should ignore the bit, and return the non-extended
> rtpg as the array doesn't support the request. Working
> around this by retrying the rtpg request without the extended
> header bit set when the extended rtpg request results in
> illegal request.
>
> Signed-off-by: Rob Evers <revers@redhat.com>
Reviewed-by: Babu Moger <babu.moger@netapp.com>
> ---
> drivers/scsi/device_handler/scsi_dh_alua.c | 26
> +++++++++++++++++++++++---
> 1 files changed, 23 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c
> b/drivers/scsi/device_handler/scsi_dh_alua.c
> index 6a7efd3..51d8cf6 100644
> --- a/drivers/scsi/device_handler/scsi_dh_alua.c
> +++ b/drivers/scsi/device_handler/scsi_dh_alua.c
> @@ -173,7 +173,8 @@ done:
> * submit_rtpg - Issue a REPORT TARGET GROUP STATES command
> * @sdev: sdev the command should be sent to
> */
> -static unsigned submit_rtpg(struct scsi_device *sdev, struct alua_dh_data
> *h)
> +static unsigned submit_rtpg(struct scsi_device *sdev, struct alua_dh_data
> *h,
> + bool rtpg_ext_hdr_req)
> {
> struct request *rq;
> int err = SCSI_DH_RES_TEMP_UNAVAIL;
> @@ -184,7 +185,10 @@ static unsigned submit_rtpg(struct scsi_device
> *sdev, struct alua_dh_data *h)
>
> /* Prepare the command. */
> rq->cmd[0] = MAINTENANCE_IN;
> - rq->cmd[1] = MI_REPORT_TARGET_PGS |
> MI_EXT_HDR_PARAM_FMT;
> + if (rtpg_ext_hdr_req)
> + rq->cmd[1] = MI_REPORT_TARGET_PGS |
> MI_EXT_HDR_PARAM_FMT;
> + else
> + rq->cmd[1] = MI_REPORT_TARGET_PGS;
> rq->cmd[6] = (h->bufflen >> 24) & 0xff;
> rq->cmd[7] = (h->bufflen >> 16) & 0xff;
> rq->cmd[8] = (h->bufflen >> 8) & 0xff;
> @@ -517,6 +521,7 @@ static int alua_rtpg(struct scsi_device *sdev, struct
> alua_dh_data *h)
> int len, k, off, valid_states = 0;
> unsigned char *ucp;
> unsigned err;
> + bool rtpg_ext_hdr_req = 1;
> unsigned long expiry, interval = 1000;
> unsigned int tpg_desc_tbl_off;
> unsigned char orig_transition_tmo;
> @@ -527,7 +532,7 @@ static int alua_rtpg(struct scsi_device *sdev, struct
> alua_dh_data *h)
> expiry = round_jiffies_up(jiffies + h->transition_tmo * HZ);
>
> retry:
> - err = submit_rtpg(sdev, h);
> + err = submit_rtpg(sdev, h, rtpg_ext_hdr_req);
>
> if (err == SCSI_DH_IO && h->senselen > 0) {
> err = scsi_normalize_sense(h->sense,
> SCSI_SENSE_BUFFERSIZE,
> @@ -535,6 +540,21 @@ static int alua_rtpg(struct scsi_device *sdev, struct
> alua_dh_data *h)
> if (!err)
> return SCSI_DH_IO;
>
> + /*
> + * submit_rtpg() has failed on existing arrays
> + * when requesting extended header info, and
> + * the array doesn't support extended headers,
> + * even though it shouldn't according to T10.
> + * The retry without rtpg_ext_hdr_req set
> + * handles this.
> + */
> + if (rtpg_ext_hdr_req == 1 &&
> + sense_hdr.sense_key == ILLEGAL_REQUEST &&
> + sense_hdr.asc == 0x24 && sense_hdr.ascq == 0) {
> + rtpg_ext_hdr_req = 0;
> + goto retry;
> + }
> +
> err = alua_check_sense(sdev, &sense_hdr);
> if (err == ADD_TO_MLQUEUE && time_before(jiffies,
> expiry))
> goto retry;
> --
> 1.7.7.2
>
> --
> 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
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH 3/3 V2] alua: backoff alua rtpg retry linearly vs. geometrically
2012-05-18 18:08 [PATCH 0/3 V2] alua updates Rob Evers
2012-05-18 18:08 ` [PATCH 1/3 V2] alua: implement 'implied transition timeout' Rob Evers
2012-05-18 18:08 ` [PATCH 2/3 V2] alua: retry alua rtpg extended header for illegal request response Rob Evers
@ 2012-05-18 18:08 ` Rob Evers
2012-05-18 18:19 ` Moger, Babu
2012-06-05 16:38 ` [PATCH 0/3 V2] alua updates Rob Evers
3 siblings, 1 reply; 8+ messages in thread
From: Rob Evers @ 2012-05-18 18:08 UTC (permalink / raw)
To: linux-scsi
Currently the backoff algorithm for when to retry alua rtpg
requests progresses geometrically as so:
2, 4, 8, 16, 32, 64... seconds.
This progression can lead to un-needed delay in retrying
alua rtpg requests when the rtpgs are delayed. A less
aggressive backoff algorithm that is additive would not
lead to such large jumps when delays start getting long, but
would backoff linearly:
2, 4, 6, 8, 10... seconds.
Signed-off-by: Martin George <marting@netapp.com>
Signed-off-by: Rob Evers <revers@redhat.com>
---
drivers/scsi/device_handler/scsi_dh_alua.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
index 51d8cf6..7eb9dea 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -522,7 +522,7 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h)
unsigned char *ucp;
unsigned err;
bool rtpg_ext_hdr_req = 1;
- unsigned long expiry, interval = 1000;
+ unsigned long expiry, interval = 0;
unsigned int tpg_desc_tbl_off;
unsigned char orig_transition_tmo;
@@ -625,7 +625,7 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h)
case TPGS_STATE_TRANSITIONING:
if (time_before(jiffies, expiry)) {
/* State transition, retry */
- interval *= 2;
+ interval += 2000;
msleep(interval);
goto retry;
}
--
1.7.7.2
^ permalink raw reply related [flat|nested] 8+ messages in thread* RE: [PATCH 3/3 V2] alua: backoff alua rtpg retry linearly vs. geometrically
2012-05-18 18:08 ` [PATCH 3/3 V2] alua: backoff alua rtpg retry linearly vs. geometrically Rob Evers
@ 2012-05-18 18:19 ` Moger, Babu
0 siblings, 0 replies; 8+ messages in thread
From: Moger, Babu @ 2012-05-18 18:19 UTC (permalink / raw)
To: Rob Evers, linux-scsi@vger.kernel.org
> -----Original Message-----
> From: linux-scsi-owner@vger.kernel.org [mailto:linux-scsi-
> owner@vger.kernel.org] On Behalf Of Rob Evers
> Sent: Friday, May 18, 2012 1:09 PM
> To: linux-scsi@vger.kernel.org
> Subject: [PATCH 3/3 V2] alua: backoff alua rtpg retry linearly vs. geometrically
>
> Currently the backoff algorithm for when to retry alua rtpg
> requests progresses geometrically as so:
>
> 2, 4, 8, 16, 32, 64... seconds.
>
> This progression can lead to un-needed delay in retrying
> alua rtpg requests when the rtpgs are delayed. A less
> aggressive backoff algorithm that is additive would not
> lead to such large jumps when delays start getting long, but
> would backoff linearly:
>
> 2, 4, 6, 8, 10... seconds.
>
> Signed-off-by: Martin George <marting@netapp.com>
> Signed-off-by: Rob Evers <revers@redhat.com>
Reviewed-by: Babu Moger <babu.moger@netapp.com>
> ---
> drivers/scsi/device_handler/scsi_dh_alua.c | 4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c
> b/drivers/scsi/device_handler/scsi_dh_alua.c
> index 51d8cf6..7eb9dea 100644
> --- a/drivers/scsi/device_handler/scsi_dh_alua.c
> +++ b/drivers/scsi/device_handler/scsi_dh_alua.c
> @@ -522,7 +522,7 @@ static int alua_rtpg(struct scsi_device *sdev, struct
> alua_dh_data *h)
> unsigned char *ucp;
> unsigned err;
> bool rtpg_ext_hdr_req = 1;
> - unsigned long expiry, interval = 1000;
> + unsigned long expiry, interval = 0;
> unsigned int tpg_desc_tbl_off;
> unsigned char orig_transition_tmo;
>
> @@ -625,7 +625,7 @@ static int alua_rtpg(struct scsi_device *sdev, struct
> alua_dh_data *h)
> case TPGS_STATE_TRANSITIONING:
> if (time_before(jiffies, expiry)) {
> /* State transition, retry */
> - interval *= 2;
> + interval += 2000;
> msleep(interval);
> goto retry;
> }
> --
> 1.7.7.2
>
> --
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> More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 0/3 V2] alua updates
2012-05-18 18:08 [PATCH 0/3 V2] alua updates Rob Evers
` (2 preceding siblings ...)
2012-05-18 18:08 ` [PATCH 3/3 V2] alua: backoff alua rtpg retry linearly vs. geometrically Rob Evers
@ 2012-06-05 16:38 ` Rob Evers
3 siblings, 0 replies; 8+ messages in thread
From: Rob Evers @ 2012-06-05 16:38 UTC (permalink / raw)
To: Hannes Reinecke; +Cc: linux-scsi
Hannes,
Do you have any feedback on these patches?
Thanks, Rob
On 05/18/2012 02:08 PM, Rob Evers wrote:
> A few minor updates to the previous alua patchset...
>
> alua: retry alua rtpg extended header for illegal request response:
> - Added entry condition to alua_rtpg ILLEGAL_REQUEST retry to avoid
> possible infinite loop. Infinte loop could occur if an array fails
> non-extended format rtpg request.
>
> - Fixed a few comment typos
>
> alua: backoff alua rtpg retry linearly vs. geometrically:
> - Added Martin George's signoff on patch as he contributed this.
>
> Rob Evers (3):
> alua: implement 'implied transition timeout'
> alua: retry alua rtpg extended header for illegal request response
> alua: backoff alua rtpg retry linearly vs. geometrically
>
> drivers/scsi/device_handler/scsi_dh_alua.c | 69 ++++++++++++++++++++++++----
> include/scsi/scsi.h | 2 +
> 2 files changed, 62 insertions(+), 9 deletions(-)
>
^ permalink raw reply [flat|nested] 8+ messages in thread