hey Eric: On Wed, Dec 11, 2019 at 11:32:40AM +0800, zhou xianrong wrote: > From: "xianrong.zhou" <[email protected]> > > If check_at_most_once enabled, just like verity work the prefetching > work should check for data block bitmap firstly before reading hash > block as well. Skip bit-set data blocks from both ends of data block > range by testing the validated bitmap. This can reduce the amounts of > data blocks which need to read hash blocks. > > Launching 91 apps every 15s and repeat 21 rounds on Android Q. > In prefetching work we can let only 2602/360312 = 0.72% data blocks > really need to read hash blocks. > > But the reduced data blocks range would be enlarged again by > dm_verity_prefetch_cluster later. > > Signed-off-by: xianrong.zhou <[email protected]> > Signed-off-by: yuanjiong.gao <[email protected]> > Tested-by: ruxian.feng <[email protected]> > --- > drivers/md/dm-verity-target.c | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > > diff --git a/drivers/md/dm-verity-target.c > b/drivers/md/dm-verity-target.c index 4fb33e7562c5..7b8eb754c0b6 > 100644 > --- a/drivers/md/dm-verity-target.c > +++ b/drivers/md/dm-verity-target.c > @@ -581,6 +581,22 @@ static void verity_prefetch_io(struct work_struct *work) > struct dm_verity *v = pw->v; > int i; > > + if (v->validated_blocks) { > + while (pw->n_blocks) { > + if (unlikely(!test_bit(pw->block, v->validated_blocks))) > + break; > + pw->block++; > + pw->n_blocks--; > + } > + while (pw->n_blocks) { > + if (unlikely(!test_bit(pw->block + pw->n_blocks - 1, > + v->validated_blocks))) > + break; > + pw->n_blocks--; > + } > + if (!pw->n_blocks) > + return; > + }
This is a good idea, but shouldn't this logic go in verity_submit_prefetch() prior to the struct dm_verity_prefetch_work being allocated? Then if no prefeching is needed, allocating and scheduling the work object can be skipped. Eric, Do you mean it is more suitable in dm_bufio_prefetch which is called on different paths even though prefeching is disabled ? Also note that you're currently leaking the work object with the early return. Right! I leaked this. always so. Thanks!!! - Eric -- dm-devel mailing list [email protected] https://www.redhat.com/mailman/listinfo/dm-devel
