On 08/03/2010 10:26 PM, michaelc@xxxxxxxxxxx wrote: > From: Mike Christie <mchristi@xxxxxxxxxx> > > We have been seeing the flush request timeout with a wide > range of hardware from tgt+iser to FC targets from a major vendor. > > I did this patch which added a flush timeout: > http://marc.info/?l=linux-scsi&m=127957359200466&w=2 > > A problem with that patch is how to determine what value > should be set and when you need to set it. You will > not know that you need to increase until it times out > and fails, then to figure out what to set it to you > need to set the timeout and try it out a couple times. > > So this patch just increases the flush/sync cache timeout > to 2 minutes. In testing, it has taken at most around 60 > seconds to complete the operation, so I thought 120 would > be safe and not add that long of delay if the device was > really jammed and needed the scsi eh. > > Signed-off-by: Mike Christie <michaelc@xxxxxxxxxxx> I'm not sure either way, but you might also use the request_queue's timeout which is settable from user-mode, times a factor like "request_queue->timeout * 4" A slow device might be slower on flush as well. Or not, just an option ;-) (Or be really smart like can_queue * single_io_timeout / 2) Boaz > --- > drivers/scsi/sd.c | 4 ++-- > drivers/scsi/sd.h | 1 + > 2 files changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c > index 108daea..3ef08bd 100644 > --- a/drivers/scsi/sd.c > +++ b/drivers/scsi/sd.c > @@ -477,7 +477,7 @@ static int scsi_setup_discard_cmnd(struct scsi_device *sdp, struct request *rq) > > static int scsi_setup_flush_cmnd(struct scsi_device *sdp, struct request *rq) > { > - rq->timeout = SD_TIMEOUT; > + rq->timeout = SD_FLUSH_TIMEOUT; > rq->retries = SD_MAX_RETRIES; > rq->cmd[0] = SYNCHRONIZE_CACHE; > rq->cmd_len = 10; > @@ -1064,7 +1064,7 @@ static int sd_sync_cache(struct scsi_disk *sdkp) > * flush everything. > */ > res = scsi_execute_req(sdp, cmd, DMA_NONE, NULL, 0, &sshdr, > - SD_TIMEOUT, SD_MAX_RETRIES, NULL); > + SD_FLUSH_TIMEOUT, SD_MAX_RETRIES, NULL); > if (res == 0) > break; > } > diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h > index f81a930..86e6dc3 100644 > --- a/drivers/scsi/sd.h > +++ b/drivers/scsi/sd.h > @@ -19,6 +19,7 @@ > */ > #define SD_TIMEOUT (30 * HZ) > #define SD_MOD_TIMEOUT (75 * HZ) > +#define SD_FLUSH_TIMEOUT (120 * HZ) > > /* > * Number of allowed retries -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
