On 09/13/2016 06:01 PM, Mike Snitzer wrote: > Return DM_MAPIO_DELAY_REQUEUE from .clone_and_map_rq. Also, return > false from .busy, if all paths are down, so that blk-mq requests get > mapped via .clone_and_map_rq -- which results in DM_MAPIO_DELAY_REQUEUE > being returned to dm-rq. > > This change allows for a noticeable reduction in cpu utilization > (reduced kworker load) while all paths are down, e.g.: > > system CPU idleness (as measured by fio's --idle-prof=system): > before: system: 87.53% > after: system: 97.07% > > Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx> > --- > drivers/md/dm-mpath.c | 15 +++++++++------ > 1 file changed, 9 insertions(+), 6 deletions(-) > Reviewed-by: Hannes Reinecke <hare@xxxxxxxx> Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@xxxxxxx +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg) -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
