Re: [PATCH] DAX: enable iostat for read/write

[Kani, Toshimitsu]

On Mon, 2016-10-17 at 11:55 -0700, Dan Williams wrote:
> On Mon, Oct 17, 2016 at 10:40 AM, Kani, Toshimitsu  m> wrote:
> > 
> > On Sat, 2016-10-15 at 18:54 +1100, Dave Chinner wrote:
> > > 
> > > On Fri, Oct 14, 2016 at 11:25:13AM -0600, Toshi Kani wrote:
> >  :
> > > 
> > > > 
> > > > +static void dax_iostat_start(struct gendisk *disk, struct
> > > > iov_iter
> > > > *iter,
> > > > + unsigned long *start)
> > > > +{
> > > > +int rw = iov_iter_rw(iter);
> > > > +int sec = iov_iter_count(iter) >> 9;
> > > > +int cpu = part_stat_lock();
> > > > +
> > > > +*start = jiffies;
> > > > +part_round_stats(cpu, >part0);
> > > > +part_stat_inc(cpu, >part0, ios[rw]);
> > > > +part_stat_add(cpu, >part0, sectors[rw], sec);
> > > > +part_inc_in_flight(>part0, rw);
> > > > +part_stat_unlock();
> > > > +}
> > > 
> > > Why reimplement generic_start_io_acct() and
> > > generic_end_io_acct()?
> > 
> > It was modeled after __nd_iostat_start() / nd_iostart_end().  I
> > agree that we can use generic_start_io_acct() and
> > generic_end_io_acct() here.
> > 
> > Should we also change the nd interface to use the generic version
> > as well?
> 
> Yes, sounds good to me.

Will do. Thanks!
-Toshi

Re: [PATCH] DAX: enable iostat for read/write

[Kani, Toshimitsu]

On Mon, 2016-10-17 at 11:55 -0700, Dan Williams wrote:
> On Mon, Oct 17, 2016 at 10:40 AM, Kani, Toshimitsu  m> wrote:
> > 
> > On Sat, 2016-10-15 at 18:54 +1100, Dave Chinner wrote:
> > > 
> > > On Fri, Oct 14, 2016 at 11:25:13AM -0600, Toshi Kani wrote:
> >  :
> > > 
> > > > 
> > > > +static void dax_iostat_start(struct gendisk *disk, struct
> > > > iov_iter
> > > > *iter,
> > > > + unsigned long *start)
> > > > +{
> > > > +int rw = iov_iter_rw(iter);
> > > > +int sec = iov_iter_count(iter) >> 9;
> > > > +int cpu = part_stat_lock();
> > > > +
> > > > +*start = jiffies;
> > > > +part_round_stats(cpu, >part0);
> > > > +part_stat_inc(cpu, >part0, ios[rw]);
> > > > +part_stat_add(cpu, >part0, sectors[rw], sec);
> > > > +part_inc_in_flight(>part0, rw);
> > > > +part_stat_unlock();
> > > > +}
> > > 
> > > Why reimplement generic_start_io_acct() and
> > > generic_end_io_acct()?
> > 
> > It was modeled after __nd_iostat_start() / nd_iostart_end().  I
> > agree that we can use generic_start_io_acct() and
> > generic_end_io_acct() here.
> > 
> > Should we also change the nd interface to use the generic version
> > as well?
> 
> Yes, sounds good to me.

Will do. Thanks!
-Toshi

Re: [PATCH] DAX: enable iostat for read/write

[Dan Williams]

On Mon, Oct 17, 2016 at 10:40 AM, Kani, Toshimitsu  wrote:
> On Sat, 2016-10-15 at 18:54 +1100, Dave Chinner wrote:
>> On Fri, Oct 14, 2016 at 11:25:13AM -0600, Toshi Kani wrote:
>  :
>> > +static void dax_iostat_start(struct gendisk *disk, struct iov_iter
>> > *iter,
>> > + unsigned long *start)
>> > +{
>> > +int rw = iov_iter_rw(iter);
>> > +int sec = iov_iter_count(iter) >> 9;
>> > +int cpu = part_stat_lock();
>> > +
>> > +*start = jiffies;
>> > +part_round_stats(cpu, >part0);
>> > +part_stat_inc(cpu, >part0, ios[rw]);
>> > +part_stat_add(cpu, >part0, sectors[rw], sec);
>> > +part_inc_in_flight(>part0, rw);
>> > +part_stat_unlock();
>> > +}
>>
>> Why reimplement generic_start_io_acct() and generic_end_io_acct()?
>
> It was modeled after __nd_iostat_start() / nd_iostart_end().  I agree
> that we can use generic_start_io_acct() and generic_end_io_acct() here.
>
> Should we also change the nd interface to use the generic version as
> well?

Yes, sounds good to me.

Re: [PATCH] DAX: enable iostat for read/write

[Dan Williams]

On Mon, Oct 17, 2016 at 10:40 AM, Kani, Toshimitsu  wrote:
> On Sat, 2016-10-15 at 18:54 +1100, Dave Chinner wrote:
>> On Fri, Oct 14, 2016 at 11:25:13AM -0600, Toshi Kani wrote:
>  :
>> > +static void dax_iostat_start(struct gendisk *disk, struct iov_iter
>> > *iter,
>> > + unsigned long *start)
>> > +{
>> > +int rw = iov_iter_rw(iter);
>> > +int sec = iov_iter_count(iter) >> 9;
>> > +int cpu = part_stat_lock();
>> > +
>> > +*start = jiffies;
>> > +part_round_stats(cpu, >part0);
>> > +part_stat_inc(cpu, >part0, ios[rw]);
>> > +part_stat_add(cpu, >part0, sectors[rw], sec);
>> > +part_inc_in_flight(>part0, rw);
>> > +part_stat_unlock();
>> > +}
>>
>> Why reimplement generic_start_io_acct() and generic_end_io_acct()?
>
> It was modeled after __nd_iostat_start() / nd_iostart_end().  I agree
> that we can use generic_start_io_acct() and generic_end_io_acct() here.
>
> Should we also change the nd interface to use the generic version as
> well?

Yes, sounds good to me.

Re: [PATCH] DAX: enable iostat for read/write

[Kani, Toshimitsu]

On Sat, 2016-10-15 at 18:54 +1100, Dave Chinner wrote:
> On Fri, Oct 14, 2016 at 11:25:13AM -0600, Toshi Kani wrote:
 :
> > +static void dax_iostat_start(struct gendisk *disk, struct iov_iter
> > *iter,
> > +    unsigned long *start)
> > +{
> > +   int rw = iov_iter_rw(iter);
> > +   int sec = iov_iter_count(iter) >> 9;
> > +   int cpu = part_stat_lock();
> > +
> > +   *start = jiffies;
> > +   part_round_stats(cpu, >part0);
> > +   part_stat_inc(cpu, >part0, ios[rw]);
> > +   part_stat_add(cpu, >part0, sectors[rw], sec);
> > +   part_inc_in_flight(>part0, rw);
> > +   part_stat_unlock();
> > +}
> 
> Why reimplement generic_start_io_acct() and generic_end_io_acct()?

It was modeled after __nd_iostat_start() / nd_iostart_end().  I agree
that we can use generic_start_io_acct() and generic_end_io_acct() here.

Should we also change the nd interface to use the generic version as
well?

Thanks,
-Toshi

ps.
Sorry I realized this comment after sending out v2...

Re: [PATCH] DAX: enable iostat for read/write

[Kani, Toshimitsu]

On Sat, 2016-10-15 at 18:54 +1100, Dave Chinner wrote:
> On Fri, Oct 14, 2016 at 11:25:13AM -0600, Toshi Kani wrote:
 :
> > +static void dax_iostat_start(struct gendisk *disk, struct iov_iter
> > *iter,
> > +    unsigned long *start)
> > +{
> > +   int rw = iov_iter_rw(iter);
> > +   int sec = iov_iter_count(iter) >> 9;
> > +   int cpu = part_stat_lock();
> > +
> > +   *start = jiffies;
> > +   part_round_stats(cpu, >part0);
> > +   part_stat_inc(cpu, >part0, ios[rw]);
> > +   part_stat_add(cpu, >part0, sectors[rw], sec);
> > +   part_inc_in_flight(>part0, rw);
> > +   part_stat_unlock();
> > +}
> 
> Why reimplement generic_start_io_acct() and generic_end_io_acct()?

It was modeled after __nd_iostat_start() / nd_iostart_end().  I agree
that we can use generic_start_io_acct() and generic_end_io_acct() here.

Should we also change the nd interface to use the generic version as
well?

Thanks,
-Toshi

ps.
Sorry I realized this comment after sending out v2...

Re: [PATCH] DAX: enable iostat for read/write

[Dave Chinner]

On Fri, Oct 14, 2016 at 11:25:13AM -0600, Toshi Kani wrote:
> DAX IO path does not support iostat, but its metadata IO path does.
> Therefore, iostat shows metadata IO statistics only, which has been
> confusing to users.
> 
> Add iostat support to the DAX read/write path.
> 
> Note, iostat still does not support the DAX mmap path as it allows
> user applications to access directly.
> 
> Signed-off-by: Toshi Kani 
> Cc: Andrew Morton 
> Cc: Alexander Viro 
> Cc: Dan Williams 
> Cc: Ross Zwisler 
> ---
>  fs/dax.c |   37 +
>  1 file changed, 37 insertions(+)
> 
> diff --git a/fs/dax.c b/fs/dax.c
> index 014defd..3c2 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -144,6 +144,34 @@ static sector_t to_sector(const struct buffer_head *bh,
>   return sector;
>  }
>  
> +static void dax_iostat_start(struct gendisk *disk, struct iov_iter *iter,
> +  unsigned long *start)
> +{
> + int rw = iov_iter_rw(iter);
> + int sec = iov_iter_count(iter) >> 9;
> + int cpu = part_stat_lock();
> +
> + *start = jiffies;
> + part_round_stats(cpu, >part0);
> + part_stat_inc(cpu, >part0, ios[rw]);
> + part_stat_add(cpu, >part0, sectors[rw], sec);
> + part_inc_in_flight(>part0, rw);
> + part_stat_unlock();
> +}

Why reimplement generic_start_io_acct() and generic_end_io_acct()?

-Dave.
-- 
Dave Chinner
da...@fromorbit.com

Re: [PATCH] DAX: enable iostat for read/write

[Dave Chinner]

On Fri, Oct 14, 2016 at 11:25:13AM -0600, Toshi Kani wrote:
> DAX IO path does not support iostat, but its metadata IO path does.
> Therefore, iostat shows metadata IO statistics only, which has been
> confusing to users.
> 
> Add iostat support to the DAX read/write path.
> 
> Note, iostat still does not support the DAX mmap path as it allows
> user applications to access directly.
> 
> Signed-off-by: Toshi Kani 
> Cc: Andrew Morton 
> Cc: Alexander Viro 
> Cc: Dan Williams 
> Cc: Ross Zwisler 
> ---
>  fs/dax.c |   37 +
>  1 file changed, 37 insertions(+)
> 
> diff --git a/fs/dax.c b/fs/dax.c
> index 014defd..3c2 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -144,6 +144,34 @@ static sector_t to_sector(const struct buffer_head *bh,
>   return sector;
>  }
>  
> +static void dax_iostat_start(struct gendisk *disk, struct iov_iter *iter,
> +  unsigned long *start)
> +{
> + int rw = iov_iter_rw(iter);
> + int sec = iov_iter_count(iter) >> 9;
> + int cpu = part_stat_lock();
> +
> + *start = jiffies;
> + part_round_stats(cpu, >part0);
> + part_stat_inc(cpu, >part0, ios[rw]);
> + part_stat_add(cpu, >part0, sectors[rw], sec);
> + part_inc_in_flight(>part0, rw);
> + part_stat_unlock();
> +}

Why reimplement generic_start_io_acct() and generic_end_io_acct()?

-Dave.
-- 
Dave Chinner
da...@fromorbit.com

Re: [PATCH] DAX: enable iostat for read/write

[Kani, Toshimitsu]

On Fri, 2016-10-14 at 10:35 -0700, Dan Williams wrote:
> On Fri, Oct 14, 2016 at 10:25 AM, Toshi Kani 
> wrote:
> > 
> > DAX IO path does not support iostat, but its metadata IO path does.
> > Therefore, iostat shows metadata IO statistics only, which has been
> > confusing to users.
> > 
> > Add iostat support to the DAX read/write path.
> > 
> > Note, iostat still does not support the DAX mmap path as it allows
> > user applications to access directly.
> > 
> > Signed-off-by: Toshi Kani 
> > Cc: Andrew Morton 
> > Cc: Alexander Viro 
> > Cc: Dan Williams 
> > Cc: Ross Zwisler 
> > ---
> >  fs/dax.c |   37 +
> >  1 file changed, 37 insertions(+)
> > 
> > diff --git a/fs/dax.c b/fs/dax.c
> > index 014defd..3c2 100644
> > --- a/fs/dax.c
> > +++ b/fs/dax.c
> > @@ -144,6 +144,34 @@ static sector_t to_sector(const struct
> > buffer_head *bh,
> > return sector;
> >  }
> > 
> > +static void dax_iostat_start(struct gendisk *disk, struct iov_iter
> > *iter,
> > +unsigned long *start)
> > +{
> > +   int rw = iov_iter_rw(iter);
> > +   int sec = iov_iter_count(iter) >> 9;
> 
> Should this be a minimum of one sector since we allow unaligned
> transfers through this interface?
> 
> ...or is iov_iter_count() somehow guaranteed to be sector aligned
> here?

You are right. I will update to set a minimum of one sector in v2. 

Thanks!
-Toshi

Re: [PATCH] DAX: enable iostat for read/write

[Kani, Toshimitsu]

On Fri, 2016-10-14 at 10:35 -0700, Dan Williams wrote:
> On Fri, Oct 14, 2016 at 10:25 AM, Toshi Kani 
> wrote:
> > 
> > DAX IO path does not support iostat, but its metadata IO path does.
> > Therefore, iostat shows metadata IO statistics only, which has been
> > confusing to users.
> > 
> > Add iostat support to the DAX read/write path.
> > 
> > Note, iostat still does not support the DAX mmap path as it allows
> > user applications to access directly.
> > 
> > Signed-off-by: Toshi Kani 
> > Cc: Andrew Morton 
> > Cc: Alexander Viro 
> > Cc: Dan Williams 
> > Cc: Ross Zwisler 
> > ---
> >  fs/dax.c |   37 +
> >  1 file changed, 37 insertions(+)
> > 
> > diff --git a/fs/dax.c b/fs/dax.c
> > index 014defd..3c2 100644
> > --- a/fs/dax.c
> > +++ b/fs/dax.c
> > @@ -144,6 +144,34 @@ static sector_t to_sector(const struct
> > buffer_head *bh,
> > return sector;
> >  }
> > 
> > +static void dax_iostat_start(struct gendisk *disk, struct iov_iter
> > *iter,
> > +unsigned long *start)
> > +{
> > +   int rw = iov_iter_rw(iter);
> > +   int sec = iov_iter_count(iter) >> 9;
> 
> Should this be a minimum of one sector since we allow unaligned
> transfers through this interface?
> 
> ...or is iov_iter_count() somehow guaranteed to be sector aligned
> here?

You are right. I will update to set a minimum of one sector in v2. 

Thanks!
-Toshi

Re: [PATCH] DAX: enable iostat for read/write

[Dan Williams]

On Fri, Oct 14, 2016 at 10:25 AM, Toshi Kani  wrote:
> DAX IO path does not support iostat, but its metadata IO path does.
> Therefore, iostat shows metadata IO statistics only, which has been
> confusing to users.
>
> Add iostat support to the DAX read/write path.
>
> Note, iostat still does not support the DAX mmap path as it allows
> user applications to access directly.
>
> Signed-off-by: Toshi Kani 
> Cc: Andrew Morton 
> Cc: Alexander Viro 
> Cc: Dan Williams 
> Cc: Ross Zwisler 
> ---
>  fs/dax.c |   37 +
>  1 file changed, 37 insertions(+)
>
> diff --git a/fs/dax.c b/fs/dax.c
> index 014defd..3c2 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -144,6 +144,34 @@ static sector_t to_sector(const struct buffer_head *bh,
> return sector;
>  }
>
> +static void dax_iostat_start(struct gendisk *disk, struct iov_iter *iter,
> +unsigned long *start)
> +{
> +   int rw = iov_iter_rw(iter);
> +   int sec = iov_iter_count(iter) >> 9;

Should this be a minimum of one sector since we allow unaligned
transfers through this interface?

...or is iov_iter_count() somehow guaranteed to be sector aligned here?

Re: [PATCH] DAX: enable iostat for read/write

[Dan Williams]

On Fri, Oct 14, 2016 at 10:25 AM, Toshi Kani  wrote:
> DAX IO path does not support iostat, but its metadata IO path does.
> Therefore, iostat shows metadata IO statistics only, which has been
> confusing to users.
>
> Add iostat support to the DAX read/write path.
>
> Note, iostat still does not support the DAX mmap path as it allows
> user applications to access directly.
>
> Signed-off-by: Toshi Kani 
> Cc: Andrew Morton 
> Cc: Alexander Viro 
> Cc: Dan Williams 
> Cc: Ross Zwisler 
> ---
>  fs/dax.c |   37 +
>  1 file changed, 37 insertions(+)
>
> diff --git a/fs/dax.c b/fs/dax.c
> index 014defd..3c2 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -144,6 +144,34 @@ static sector_t to_sector(const struct buffer_head *bh,
> return sector;
>  }
>
> +static void dax_iostat_start(struct gendisk *disk, struct iov_iter *iter,
> +unsigned long *start)
> +{
> +   int rw = iov_iter_rw(iter);
> +   int sec = iov_iter_count(iter) >> 9;

Should this be a minimum of one sector since we allow unaligned
transfers through this interface?

...or is iov_iter_count() somehow guaranteed to be sector aligned here?