On Thu, Jul 18, 2024 at 10:24:13PM +0200, Martin Wilck wrote: > On Wed, 2024-07-17 at 14:11 -0400, Benjamin Marzinski wrote: > > multipathd's path checking can be very bursty, with all the paths > > running their path checkers at the same time, and then all doing > > nothing > > while waiting for the next check time. Alternatively, the paths in a > > multipath device might all run their path checkers at a different > > time, > > which can keep the multipath device from having a coherent view of > > the > > state of all of its paths. > > > > This patch makes all the paths of a multipath device converge to > > running > > their checkers at the same time, and spreads out when this time is > > for > > the different multipath devices. > > > > To do this, the checking time is divided into adjustment intervals > > (conf->adjust_int), so that the checkers run at some index within > > this > > interval. conf->adjust_int is chosen so that it is a multiple of all > > possible pp->checkint values. This means that regardless of > > pp->checkint, the path should always be checked on the same indexes, > > each adjustement interval. > > > > Each multipath device has a goal index. These are evenly spread out > > between 0 and conf->max_checkint. Every conf->adjust_int seconds, > > each > > multipath device should try to check all of its paths on its goal > > index. > > If the multipath device's check times are not aligned with the goal > > index, then pp->tick for the next check will be decremented by one, > > to > > align it over time. > > > > In order for the path checkers to run every pp->checkint seconds, > > multipathd needs to track how long a path check has been pending for, > > and subtract that time from the number of ticks till the checker is > > run > > again. If the checker has been pending for more that pp->checkint, > > the path will be rechecked on the next tick after the checker > > returns. > > > > Signed-off-by: Benjamin Marzinski <[email protected]> > > --- > > libmultipath/config.c | 12 ++++++ > > libmultipath/config.h | 1 + > > libmultipath/structs.c | 1 + > > libmultipath/structs.h | 1 + > > multipathd/main.c | 91 ++++++++++++++++++++++++++++++++++------ > > -- > > 5 files changed, 89 insertions(+), 17 deletions(-) > > > > diff --git a/libmultipath/config.c b/libmultipath/config.c > > index 83fa7369..a59533b5 100644 > > --- a/libmultipath/config.c > > +++ b/libmultipath/config.c > > @@ -982,6 +982,18 @@ int _init_config (const char *file, struct > > config *conf) > > conf->checkint = conf->max_checkint; > > condlog(3, "polling interval: %d, max: %d", > > conf->checkint, conf->max_checkint); > > + /* > > + * make sure that that adjust_int is a multiple of all > > possible values > > + * of pp->checkint. > > + */ > > + if (conf->max_checkint % conf->checkint == 0) { > > + conf->adjust_int = conf->max_checkint; > > + } else { > > + conf->adjust_int = conf->checkint; > > + while (2 * conf->adjust_int < conf->max_checkint) > > + conf->adjust_int *= 2; > > + conf->adjust_int *= conf->max_checkint; > > + } > > > > if (conf->blist_devnode == NULL) { > > conf->blist_devnode = vector_alloc(); > > diff --git a/libmultipath/config.h b/libmultipath/config.h > > index 384193ab..800c0ca9 100644 > > --- a/libmultipath/config.h > > +++ b/libmultipath/config.h > > @@ -147,6 +147,7 @@ struct config { > > int minio_rq; > > unsigned int checkint; > > unsigned int max_checkint; > > + unsigned int adjust_int; > > bool use_watchdog; > > int pgfailback; > > int rr_weight; > > diff --git a/libmultipath/structs.c b/libmultipath/structs.c > > index 0a26096a..232b4230 100644 > > --- a/libmultipath/structs.c > > +++ b/libmultipath/structs.c > > @@ -149,6 +149,7 @@ uninitialize_path(struct path *pp) > > pp->state = PATH_UNCHECKED; > > pp->uid_attribute = NULL; > > pp->checker_timeout = 0; > > + pp->pending_ticks = 0; > > > > if (checker_selected(&pp->checker)) > > checker_put(&pp->checker); > > diff --git a/libmultipath/structs.h b/libmultipath/structs.h > > index 002eeae1..457d7836 100644 > > --- a/libmultipath/structs.h > > +++ b/libmultipath/structs.h > > @@ -360,6 +360,7 @@ struct path { > > unsigned long long size; > > unsigned int checkint; > > unsigned int tick; > > + unsigned int pending_ticks; > > int bus; > > int offline; > > int state; > > diff --git a/multipathd/main.c b/multipathd/main.c > > index 84450906..87ddb101 100644 > > --- a/multipathd/main.c > > +++ b/multipathd/main.c > > @@ -2388,7 +2388,7 @@ enum check_path_return { > > }; > > > > static int > > -check_path (struct vectors * vecs, struct path * pp, unsigned int > > ticks) > > +do_check_path (struct vectors * vecs, struct path * pp) > > { > > int newstate; > > int new_path_up = 0; > > @@ -2400,14 +2400,6 @@ check_path (struct vectors * vecs, struct path > > * pp, unsigned int ticks) > > int marginal_pathgroups, marginal_changed = 0; > > bool need_reload; > > > > - if (pp->initialized == INIT_REMOVED) > > - return CHECK_PATH_SKIPPED; > > - > > - if (pp->tick) > > - pp->tick -= (pp->tick > ticks) ? ticks : pp->tick; > > - if (pp->tick) > > - return CHECK_PATH_SKIPPED; > > - > > conf = get_multipath_config(); > > checkint = conf->checkint; > > max_checkint = conf->max_checkint; > > @@ -2419,12 +2411,6 @@ check_path (struct vectors * vecs, struct path > > * pp, unsigned int ticks) > > pp->checkint = checkint; > > }; > > > > - /* > > - * provision a next check soonest, > > - * in case we exit abnormally from here > > - */ > > - pp->tick = checkint; > > - > > newstate = check_path_state(pp); > > if (newstate == PATH_WILD || newstate == PATH_UNCHECKED) > > return CHECK_PATH_SKIPPED; > > @@ -2587,7 +2573,6 @@ check_path (struct vectors * vecs, struct path > > * pp, unsigned int ticks) > > condlog(4, "%s: delay next check > > %is", > > pp->dev_t, pp->checkint); > > } > > - pp->tick = pp->checkint; > > } > > } > > else if (newstate != PATH_UP && newstate != PATH_GHOST) { > > @@ -2640,6 +2625,77 @@ check_path (struct vectors * vecs, struct path > > * pp, unsigned int ticks) > > return CHECK_PATH_CHECKED; > > } > > > > +static int > > +check_path (struct vectors * vecs, struct path * pp, unsigned int > > ticks, > > + time_t start_secs) > > +{ > > + int r; > > + unsigned int adjust_int, max_checkint; > > + struct config *conf; > > + time_t next_idx, goal_idx; > > + > > + if (pp->initialized == INIT_REMOVED) > > + return CHECK_PATH_SKIPPED; > > + > > + if (pp->tick) > > + pp->tick -= (pp->tick > ticks) ? ticks : pp->tick; > > + if (pp->tick) > > + return CHECK_PATH_SKIPPED; > > + > > + conf = get_multipath_config(); > > + max_checkint = conf->max_checkint; > > + adjust_int = conf->adjust_int; > > + put_multipath_config(conf); > > + > > + r = do_check_path(vecs, pp); > > + > > + /* > > + * do_check_path() removed or orphaned the path. > > + */ > > + if (r < 0 || !pp->mpp) > > + return r; > > do_check_path() returns an enum now, so this should be r == > CHECK_PATH_REMOVED.
Oops. Good catch. -Ben >
