| Message ID | 20171009073730.8939-2-mlyle@lyle.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 2017/10/9 下午3:37, Michael Lyle wrote: > The previous code artificially limited writeback rate to 1000000 > blocks/second (NSEC_PER_MSEC), which is a rate that can be met on fast > hardware. The rate limiting code works fine (though with decreased > precision) up to 3 orders of magnitude faster, so use NSEC_PER_SEC. > > Additionally, ensure that uint32_t is used as a type for rate throughout > the rate management so that type checking/clamp_t can work properly. > > bch_next_delay should be rewritten for increased precision and better > handling of high rates and long sleep periods, but this is adequate for > now. > > Signed-off-by: Michael Lyle <mlyle@lyle.org> > Reported-by: Coly Li <colyli@suse.de> Current maximum rate number is around 488.2M/sec, it could be easily a bottleneck for md raid0 deivce with SATA SSD or more hard drives. The new maximum rate (476G/sec) should be enough for most of common hardware configurations :-) Reviewed-by: Coly Li <colyli@suse.de> Thanks. Coly Li > --- > drivers/md/bcache/bcache.h | 2 +- > drivers/md/bcache/util.h | 4 ++-- > drivers/md/bcache/writeback.c | 7 ++++--- > 3 files changed, 7 insertions(+), 6 deletions(-) > > diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h > index df0b2ccfca8d..2f9c380c4692 100644 > --- a/drivers/md/bcache/bcache.h > +++ b/drivers/md/bcache/bcache.h > @@ -363,7 +363,7 @@ struct cached_dev { > int64_t writeback_rate_proportional; > int64_t writeback_rate_integral; > int64_t writeback_rate_integral_scaled; > - int64_t writeback_rate_change; > + int32_t writeback_rate_change; > > unsigned writeback_rate_update_seconds; > unsigned writeback_rate_i_term_inverse; > diff --git a/drivers/md/bcache/util.h b/drivers/md/bcache/util.h > index cb8d2ccbb6c6..8f509290bb02 100644 > --- a/drivers/md/bcache/util.h > +++ b/drivers/md/bcache/util.h > @@ -441,10 +441,10 @@ struct bch_ratelimit { > uint64_t next; > > /* > - * Rate at which we want to do work, in units per nanosecond > + * Rate at which we want to do work, in units per second > * The units here correspond to the units passed to bch_next_delay() > */ > - unsigned rate; > + uint32_t rate; > }; > > static inline void bch_ratelimit_reset(struct bch_ratelimit *d) > diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c > index d63356a60001..42d087b9fb56 100644 > --- a/drivers/md/bcache/writeback.c > +++ b/drivers/md/bcache/writeback.c > @@ -52,7 +52,8 @@ static void __update_writeback_rate(struct cached_dev *dc) > int64_t error = dirty - target; > int64_t proportional_scaled = > div_s64(error, dc->writeback_rate_p_term_inverse); > - int64_t integral_scaled, new_rate; > + int64_t integral_scaled; > + uint32_t new_rate; > > if ((error < 0 && dc->writeback_rate_integral > 0) || > (error > 0 && time_before64(local_clock(), > @@ -74,8 +75,8 @@ static void __update_writeback_rate(struct cached_dev *dc) > integral_scaled = div_s64(dc->writeback_rate_integral, > dc->writeback_rate_i_term_inverse); > > - new_rate = clamp_t(int64_t, (proportional_scaled + integral_scaled), > - dc->writeback_rate_minimum, NSEC_PER_MSEC); > + new_rate = clamp_t(int32_t, (proportional_scaled + integral_scaled), > + dc->writeback_rate_minimum, NSEC_PER_SEC); > > dc->writeback_rate_proportional = proportional_scaled; > dc->writeback_rate_integral_scaled = integral_scaled;
diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h index df0b2ccfca8d..2f9c380c4692 100644 --- a/drivers/md/bcache/bcache.h +++ b/drivers/md/bcache/bcache.h @@ -363,7 +363,7 @@ struct cached_dev { int64_t writeback_rate_proportional; int64_t writeback_rate_integral; int64_t writeback_rate_integral_scaled; - int64_t writeback_rate_change; + int32_t writeback_rate_change; unsigned writeback_rate_update_seconds; unsigned writeback_rate_i_term_inverse; diff --git a/drivers/md/bcache/util.h b/drivers/md/bcache/util.h index cb8d2ccbb6c6..8f509290bb02 100644 --- a/drivers/md/bcache/util.h +++ b/drivers/md/bcache/util.h @@ -441,10 +441,10 @@ struct bch_ratelimit { uint64_t next; /* - * Rate at which we want to do work, in units per nanosecond + * Rate at which we want to do work, in units per second * The units here correspond to the units passed to bch_next_delay() */ - unsigned rate; + uint32_t rate; }; static inline void bch_ratelimit_reset(struct bch_ratelimit *d) diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c index d63356a60001..42d087b9fb56 100644 --- a/drivers/md/bcache/writeback.c +++ b/drivers/md/bcache/writeback.c @@ -52,7 +52,8 @@ static void __update_writeback_rate(struct cached_dev *dc) int64_t error = dirty - target; int64_t proportional_scaled = div_s64(error, dc->writeback_rate_p_term_inverse); - int64_t integral_scaled, new_rate; + int64_t integral_scaled; + uint32_t new_rate; if ((error < 0 && dc->writeback_rate_integral > 0) || (error > 0 && time_before64(local_clock(), @@ -74,8 +75,8 @@ static void __update_writeback_rate(struct cached_dev *dc) integral_scaled = div_s64(dc->writeback_rate_integral, dc->writeback_rate_i_term_inverse); - new_rate = clamp_t(int64_t, (proportional_scaled + integral_scaled), - dc->writeback_rate_minimum, NSEC_PER_MSEC); + new_rate = clamp_t(int32_t, (proportional_scaled + integral_scaled), + dc->writeback_rate_minimum, NSEC_PER_SEC); dc->writeback_rate_proportional = proportional_scaled; dc->writeback_rate_integral_scaled = integral_scaled;
The previous code artificially limited writeback rate to 1000000 blocks/second (NSEC_PER_MSEC), which is a rate that can be met on fast hardware. The rate limiting code works fine (though with decreased precision) up to 3 orders of magnitude faster, so use NSEC_PER_SEC. Additionally, ensure that uint32_t is used as a type for rate throughout the rate management so that type checking/clamp_t can work properly. bch_next_delay should be rewritten for increased precision and better handling of high rates and long sleep periods, but this is adequate for now. Signed-off-by: Michael Lyle <mlyle@lyle.org> Reported-by: Coly Li <colyli@suse.de> --- drivers/md/bcache/bcache.h | 2 +- drivers/md/bcache/util.h | 4 ++-- drivers/md/bcache/writeback.c | 7 ++++--- 3 files changed, 7 insertions(+), 6 deletions(-)