blk-wbt: Cleanup some comments

[PATCH] blk-wbt: Cleanup some comments

Posted by Tang Yizhou 10 months, 1 week ago

From: Tang Yizhou <yizhou.tang@shopee.com>

wbt_wait() no longer uses a spinlock as a parameter. Update the
function comments accordingly.

Additionally, revise other comments to ensure they align with the
actual implementation.

Signed-off-by: Tang Yizhou <yizhou.tang@shopee.com>
---
 block/blk-wbt.c | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/block/blk-wbt.c b/block/blk-wbt.c
index 6dfc659d22e2..f1754d07f7e0 100644
--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -136,8 +136,9 @@ enum {
 	RWB_MIN_WRITE_SAMPLES	= 3,
 
 	/*
-	 * If we have this number of consecutive windows with not enough
-	 * information to scale up or down, scale up.
+	 * If we have this number of consecutive windows without enough
+	 * information to scale up or down, slowly return to center state
+	 * (step == 0).
 	 */
 	RWB_UNKNOWN_BUMP	= 5,
 };
@@ -446,9 +447,9 @@ static void wb_timer_fn(struct blk_stat_callback *cb)
 		break;
 	case LAT_UNKNOWN_WRITES:
 		/*
-		 * We started a the center step, but don't have a valid
-		 * read/write sample, but we do have writes going on.
-		 * Allow step to go negative, to increase write perf.
+		 * We don't have a valid read/write sample, but we do have
+		 * writes going on. Allow step to go negative, to increase
+		 * write performance.
 		 */
 		scale_up(rwb);
 		break;
@@ -638,11 +639,7 @@ static void wbt_cleanup(struct rq_qos *rqos, struct bio *bio)
 	__wbt_done(rqos, flags);
 }
 
-/*
- * May sleep, if we have exceeded the writeback limits. Caller can pass
- * in an irq held spinlock, if it holds one when calling this function.
- * If we do sleep, we'll release and re-grab it.
- */
+/* May sleep, if we have exceeded the writeback limits. */
 static void wbt_wait(struct rq_qos *rqos, struct bio *bio)
 {
 	struct rq_wb *rwb = RQWB(rqos);
-- 
2.25.1

Re: [PATCH] blk-wbt: Cleanup some comments

Posted by Yu Kuai 10 months, 1 week ago

Hi,

在 2025/02/12 11:00, Tang Yizhou 写道:
> From: Tang Yizhou <yizhou.tang@shopee.com>
> 
> wbt_wait() no longer uses a spinlock as a parameter. Update the
> function comments accordingly.
> 
> Additionally, revise other comments to ensure they align with the
> actual implementation.
> 
> Signed-off-by: Tang Yizhou <yizhou.tang@shopee.com>
> ---
>   block/blk-wbt.c | 17 +++++++----------
>   1 file changed, 7 insertions(+), 10 deletions(-)
> 
> diff --git a/block/blk-wbt.c b/block/blk-wbt.c
> index 6dfc659d22e2..f1754d07f7e0 100644
> --- a/block/blk-wbt.c
> +++ b/block/blk-wbt.c
> @@ -136,8 +136,9 @@ enum {
>   	RWB_MIN_WRITE_SAMPLES	= 3,
>   
>   	/*
> -	 * If we have this number of consecutive windows with not enough
> -	 * information to scale up or down, scale up.
> +	 * If we have this number of consecutive windows without enough
> +	 * information to scale up or down, slowly return to center state
> +	 * (step == 0).
>   	 */
>   	RWB_UNKNOWN_BUMP	= 5,
>   };
> @@ -446,9 +447,9 @@ static void wb_timer_fn(struct blk_stat_callback *cb)
>   		break;
>   	case LAT_UNKNOWN_WRITES:
>   		/*
> -		 * We started a the center step, but don't have a valid
> -		 * read/write sample, but we do have writes going on.
> -		 * Allow step to go negative, to increase write perf.
> +		 * We don't have a valid read/write sample, but we do have
> +		 * writes going on. Allow step to go negative, to increase
> +		 * write performance.

Other than this clean up, the others are actually fix. Can you remove
this one and change the title to "Fix some comments"?

Thanks,
Kuai

>   		 */
>   		scale_up(rwb);
>   		break;
> @@ -638,11 +639,7 @@ static void wbt_cleanup(struct rq_qos *rqos, struct bio *bio)
>   	__wbt_done(rqos, flags);
>   }
>   
> -/*
> - * May sleep, if we have exceeded the writeback limits. Caller can pass
> - * in an irq held spinlock, if it holds one when calling this function.
> - * If we do sleep, we'll release and re-grab it.
> - */
> +/* May sleep, if we have exceeded the writeback limits. */
>   static void wbt_wait(struct rq_qos *rqos, struct bio *bio)
>   {
>   	struct rq_wb *rwb = RQWB(rqos);
>

Re: [PATCH] blk-wbt: Cleanup some comments

Posted by Yizhou Tang 10 months, 1 week ago

On Thu, Feb 13, 2025 at 10:56 AM Yu Kuai <yukuai1@huaweicloud.com> wrote:
>
> Hi,
>
> 在 2025/02/12 11:00, Tang Yizhou 写道:
> > From: Tang Yizhou <yizhou.tang@shopee.com>
> >
> > wbt_wait() no longer uses a spinlock as a parameter. Update the
> > function comments accordingly.
> >
> > Additionally, revise other comments to ensure they align with the
> > actual implementation.
> >
> > Signed-off-by: Tang Yizhou <yizhou.tang@shopee.com>
> > ---
> >   block/blk-wbt.c | 17 +++++++----------
> >   1 file changed, 7 insertions(+), 10 deletions(-)
> >
> > diff --git a/block/blk-wbt.c b/block/blk-wbt.c
> > index 6dfc659d22e2..f1754d07f7e0 100644
> > --- a/block/blk-wbt.c
> > +++ b/block/blk-wbt.c
> > @@ -136,8 +136,9 @@ enum {
> >       RWB_MIN_WRITE_SAMPLES   = 3,
> >
> >       /*
> > -      * If we have this number of consecutive windows with not enough
> > -      * information to scale up or down, scale up.
> > +      * If we have this number of consecutive windows without enough
> > +      * information to scale up or down, slowly return to center state
> > +      * (step == 0).
> >        */
> >       RWB_UNKNOWN_BUMP        = 5,
> >   };
> > @@ -446,9 +447,9 @@ static void wb_timer_fn(struct blk_stat_callback *cb)
> >               break;
> >       case LAT_UNKNOWN_WRITES:
> >               /*
> > -              * We started a the center step, but don't have a valid
> > -              * read/write sample, but we do have writes going on.
> > -              * Allow step to go negative, to increase write perf.
> > +              * We don't have a valid read/write sample, but we do have
> > +              * writes going on. Allow step to go negative, to increase
> > +              * write performance.
>
> Other than this clean up, the others are actually fix. Can you remove
> this one and change the title to "Fix some comments"?
>
> Thanks,
> Kuai
>

Will do.

Thanks
Yi

> >                */
> >               scale_up(rwb);
> >               break;
> > @@ -638,11 +639,7 @@ static void wbt_cleanup(struct rq_qos *rqos, struct bio *bio)
> >       __wbt_done(rqos, flags);
> >   }
> >
> > -/*
> > - * May sleep, if we have exceeded the writeback limits. Caller can pass
> > - * in an irq held spinlock, if it holds one when calling this function.
> > - * If we do sleep, we'll release and re-grab it.
> > - */
> > +/* May sleep, if we have exceeded the writeback limits. */
> >   static void wbt_wait(struct rq_qos *rqos, struct bio *bio)
> >   {
> >       struct rq_wb *rwb = RQWB(rqos);
> >
>
>