[SCSI] scsi_dh_alua: backoff alua rtpg retry linearly vs. geometrically
authorRob Evers <revers@redhat.com>
Fri, 18 May 2012 18:08:56 +0000 (14:08 -0400)
committerJames Bottomley <JBottomley@Parallels.com>
Fri, 20 Jul 2012 07:58:33 +0000 (08:58 +0100)
commitbc97f4bb4490ff31b2be8e006f750d4187ef0c7e
treed6099236a840c8027dca206835541dede00f63af
parent8e67ce6072a0ab7fcefbbd2913fa4eaf3fdd8d68
[SCSI] scsi_dh_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>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
drivers/scsi/device_handler/scsi_dh_alua.c