* Reply [PATCH] dm-verity: unnecessary data blocks that need not read hash blocks
@ 2019-12-16 2:02 xianrong.zhou(周先荣)
2019-12-16 18:50 ` Eric Biggers
0 siblings, 1 reply; 3+ messages in thread
From: xianrong.zhou(周先荣) @ 2019-12-16 2:02 UTC (permalink / raw)
To: Eric Biggers
Cc: dm-devel, weimin.mao(毛卫民),
haizhou.song(宋海舟),
snitzer, wanbin.wang(汪万斌),
linux-kernel, yuanjiong.gao(高渊炯),
ruxian.feng(冯儒娴),
agk
hey Eric:
On Wed, Dec 11, 2019 at 11:32:40AM +0800, zhou xianrong wrote:
> From: "xianrong.zhou" <xianrong.zhou@transsion.com>
>
> 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 <xianrong.zhou@transsion.com>
> Signed-off-by: yuanjiong.gao <yuanjiong.gao@transsion.com>
> Tested-by: ruxian.feng <ruxian.feng@transsion.com>
> ---
> 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
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] dm-verity: unnecessary data blocks that need not read hash blocks
2019-12-16 2:02 Reply [PATCH] dm-verity: unnecessary data blocks that need not read hash blocks xianrong.zhou(周先荣)
@ 2019-12-16 18:50 ` Eric Biggers
2020-01-03 18:24 ` [dm-devel] " Eric Biggers
0 siblings, 1 reply; 3+ messages in thread
From: Eric Biggers @ 2019-12-16 18:50 UTC (permalink / raw)
To: xianrong.zhou(周先荣)
Cc: dm-devel, weimin.mao(毛卫民),
haizhou.song(宋海舟),
snitzer, wanbin.wang(汪万斌),
linux-kernel, yuanjiong.gao(高渊炯),
ruxian.feng(冯儒娴),
agk
On Mon, Dec 16, 2019 at 02:02:33AM +0000, xianrong.zhou(周先荣) wrote:
> hey Eric:
>
> On Wed, Dec 11, 2019 at 11:32:40AM +0800, zhou xianrong wrote:
> > From: "xianrong.zhou" <xianrong.zhou@transsion.com>
> >
> > 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 <xianrong.zhou@transsion.com>
> > Signed-off-by: yuanjiong.gao <yuanjiong.gao@transsion.com>
> > Tested-by: ruxian.feng <ruxian.feng@transsion.com>
> > ---
> > 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 ?
>
No, I'm talking about verity_submit_prefetch(). verity_submit_prefetch()
allocates and schedules a work object, which executes verity_prefetch_io().
If all data blocks in the I/O request were already validated, there's no need to
allocate and schedule the prefetch work.
- Eric
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [dm-devel] [PATCH] dm-verity: unnecessary data blocks that need not read hash blocks
2019-12-16 18:50 ` Eric Biggers
@ 2020-01-03 18:24 ` Eric Biggers
0 siblings, 0 replies; 3+ messages in thread
From: Eric Biggers @ 2020-01-03 18:24 UTC (permalink / raw)
To: xianrong.zhou(周先荣)
Cc: weimin.mao(毛卫民),
haizhou.song(宋海舟),
snitzer, wanbin.wang(汪万斌),
linux-kernel, yuanjiong.gao(高渊炯),
dm-devel, ruxian.feng(冯儒娴),
agk
On Mon, Dec 16, 2019 at 10:50:26AM -0800, Eric Biggers wrote:
> On Mon, Dec 16, 2019 at 02:02:33AM +0000, xianrong.zhou(周先荣) wrote:
> > hey Eric:
> >
> > On Wed, Dec 11, 2019 at 11:32:40AM +0800, zhou xianrong wrote:
> > > From: "xianrong.zhou" <xianrong.zhou@transsion.com>
> > >
> > > 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 <xianrong.zhou@transsion.com>
> > > Signed-off-by: yuanjiong.gao <yuanjiong.gao@transsion.com>
> > > Tested-by: ruxian.feng <ruxian.feng@transsion.com>
> > > ---
> > > 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 ?
> >
>
> No, I'm talking about verity_submit_prefetch(). verity_submit_prefetch()
> allocates and schedules a work object, which executes verity_prefetch_io().
> If all data blocks in the I/O request were already validated, there's no need to
> allocate and schedule the prefetch work.
>
> - Eric
>
Are you planning to send a new version of this patch?
- Eric
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-01-03 18:24 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2019-12-16 2:02 Reply [PATCH] dm-verity: unnecessary data blocks that need not read hash blocks xianrong.zhou(周先荣)
2019-12-16 18:50 ` Eric Biggers
2020-01-03 18:24 ` [dm-devel] " Eric Biggers
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