On Fri, Feb 17 2017, Shaohua Li wrote: > Bump the flush stripe batch size to 2048. For my 12 disks raid > array, the stripes takes: > 12 * 4k * 2048 = 96MB > > This is still quite small. A hardware raid card generally has 1GB size, > which we suggest the raid5-cache has similar cache size. > > The advantage of a big batch size is we can dispatch a lot of IO in the > same time, then we can do some scheduling to make better IO pattern. > > Last patch prioritizes stripes, so we don't worry about a big flush > stripe batch will starve normal stripes. > > Signed-off-by: Shaohua Li <shli@xxxxxx> > --- > drivers/md/raid5-cache.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c > index 3f307be..b25512c 100644 > --- a/drivers/md/raid5-cache.c > +++ b/drivers/md/raid5-cache.c > @@ -43,7 +43,7 @@ > /* wake up reclaim thread periodically */ > #define R5C_RECLAIM_WAKEUP_INTERVAL (30 * HZ) > /* start flush with these full stripes */ > -#define R5C_FULL_STRIPE_FLUSH_BATCH 256 > +#define R5C_FULL_STRIPE_FLUSH_BATCH 2048 Fixed numbers are warning signs... I wonder if there is something better we could do? "conf->max_nr_stripes / 4" maybe? We use that sort of number elsewhere. Would that make sense? Thanks, NeilBrown > /* reclaim stripes in groups */ > #define R5C_RECLAIM_STRIPE_GROUP (NR_STRIPE_HASH_LOCKS * 2) > > -- > 2.9.3
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