Hello, Few weeks back I posted some issues w.r.t the way path priorities are used during path switching. Here is Hannes's latest response (http://marc.info/?l=dm-devel&m=124573807907764&w=2) and this patch is based on his suggestion. regards, chandra ----------------------------------------------------------------------- Failback happens only when the sum of priorities of all paths (on the higher priority path group) is greater than the sum of priorities of all paths on the lower priority path group. This leads into problems when there are more than one paths in each of the path groups, and the sum of all paths in the lower priority path group is greater than that of path priority of a single high priority path. This patch fixes the problem by using average priority of a path group in deciding path group switch over. Signed-off-by: Chandra Seetharaman <sekharan@xxxxxxxxxx> --- libmultipath/structs.h | 1 + libmultipath/switchgroup.c | 23 ++++++++++++++++++----- 2 files changed, 19 insertions(+), 5 deletions(-) Index: multipath-tools-mainline/libmultipath/structs.h =================================================================== --- multipath-tools-mainline.orig/libmultipath/structs.h +++ multipath-tools-mainline/libmultipath/structs.h @@ -202,6 +202,7 @@ struct pathgroup { long id; int status; int priority; + int up_paths; vector paths; char * selector; }; Index: multipath-tools-mainline/libmultipath/switchgroup.c =================================================================== --- multipath-tools-mainline.orig/libmultipath/switchgroup.c +++ multipath-tools-mainline/libmultipath/switchgroup.c @@ -14,13 +14,16 @@ path_group_prio_update (struct pathgroup int priority = 0; struct path * pp; + pgp->up_paths = 0; if (!pgp->paths) { pgp->priority = 0; return; } vector_foreach_slot (pgp->paths, pp, i) { - if (pp->state != PATH_DOWN) + if (pp->state != PATH_DOWN) { priority += pp->priority; + pgp->up_paths++; + } } pgp->priority = priority; } @@ -29,8 +32,9 @@ extern int select_path_group (struct multipath * mpp) { int i; - int highest = 0; + int highest_avg = 0; int bestpg = 1; + int avg_priority, highest_up_paths = 1; struct pathgroup * pgp; if (!mpp->pg) @@ -41,9 +45,18 @@ select_path_group (struct multipath * mp continue; path_group_prio_update(pgp); - if (pgp->priority > highest) { - highest = pgp->priority; - bestpg = i + 1; + if (pgp->up_paths) { + avg_priority = pgp->priority / pgp->up_paths; + if (avg_priority > highest_avg) { + highest_avg = avg_priority; + highest_up_paths = pgp->up_paths; + bestpg = i + 1; + } else if (avg_priority == highest_avg) { + if (pgp->up_paths > highest_up_paths) { + highest_up_paths = pgp->up_paths; + bestpg = i + 1; + } + } } } return bestpg; -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
