linux-kernel - Re: [PATCH 1/3][v2] blkio: Remove per-cfqq nr

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Date:	Mon, 5 Apr 2010 09:57:08 -0700
From:	Divyesh Shah <dpshah@...gle.com>
To:	Vivek Goyal <vgoyal@...hat.com>
Cc:	jens.axboe@...cle.com, linux-kernel@...r.kernel.org,
	nauman@...gle.com, ctalbott@...gle.com
Subject: Re: [PATCH 1/3][v2] blkio: Remove per-cfqq nr_sectors as we'll be 
	passing

On Mon, Apr 5, 2010 at 8:47 AM, Vivek Goyal <vgoyal@...hat.com> wrote:
> On Fri, Apr 02, 2010 at 06:55:48PM -0700, Divyesh Shah wrote:
>> that info at request dispatch with other stats now. This patch removes the
>> existing support for accounting sectors for a blkio_group. This will be added
>> back differently in the next two patches.
>>
>> Signed-off-by: Divyesh Shah<dpshah@...gle.com>
>> ---
>>
>>  block/blk-cgroup.c  |    3 +--
>>  block/blk-cgroup.h  |    6 ++----
>>  block/cfq-iosched.c |   10 ++--------
>>  3 files changed, 5 insertions(+), 14 deletions(-)
>>
>> diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
>> index 4b686ad..5be3981 100644
>> --- a/block/blk-cgroup.c
>> +++ b/block/blk-cgroup.c
>> @@ -56,10 +56,9 @@ struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup)
>>  EXPORT_SYMBOL_GPL(cgroup_to_blkio_cgroup);
>>
>>  void blkiocg_update_blkio_group_stats(struct blkio_group *blkg,
>> -                     unsigned long time, unsigned long sectors)
>> +                                             unsigned long time)
>>  {
>>       blkg->time += time;
>> -     blkg->sectors += sectors;
>>  }
>>  EXPORT_SYMBOL_GPL(blkiocg_update_blkio_group_stats);
>>
>> diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
>> index 8ccc204..fe44517 100644
>> --- a/block/blk-cgroup.h
>> +++ b/block/blk-cgroup.h
>> @@ -106,7 +106,7 @@ extern int blkiocg_del_blkio_group(struct blkio_group *blkg);
>>  extern struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg,
>>                                               void *key);
>>  void blkiocg_update_blkio_group_stats(struct blkio_group *blkg,
>> -                     unsigned long time, unsigned long sectors);
>> +                                             unsigned long time);
>>  #else
>>  struct cgroup;
>>  static inline struct blkio_cgroup *
>> @@ -123,8 +123,6 @@ blkiocg_del_blkio_group(struct blkio_group *blkg) { return 0; }
>>  static inline struct blkio_group *
>>  blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key) { return NULL; }
>>  static inline void blkiocg_update_blkio_group_stats(struct blkio_group *blkg,
>> -                     unsigned long time, unsigned long sectors)
>> -{
>> -}
>> +                                             unsigned long time) {}
>>  #endif
>>  #endif /* _BLK_CGROUP_H */
>> diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
>> index ef1680b..c18e348 100644
>> --- a/block/cfq-iosched.c
>> +++ b/block/cfq-iosched.c
>> @@ -141,8 +141,6 @@ struct cfq_queue {
>>       struct cfq_queue *new_cfqq;
>>       struct cfq_group *cfqg;
>>       struct cfq_group *orig_cfqg;
>> -     /* Sectors dispatched in current dispatch round */
>> -     unsigned long nr_sectors;
>>  };
>>
>>  /*
>> @@ -882,8 +880,7 @@ static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq)
>>                       slice_used = cfqq->allocated_slice;
>>       }
>>
>> -     cfq_log_cfqq(cfqq->cfqd, cfqq, "sl_used=%u sect=%lu", slice_used,
>> -                             cfqq->nr_sectors);
>> +     cfq_log_cfqq(cfqq->cfqd, cfqq, "sl_used=%u", slice_used);
>
> Hi Divyesh,
>
> I had found above message useful when I am looking at blktraces. It helps
> to know how many sectors one could transfer in a given time slice.
> Especially if you are comparing two queues in two groups. I think we are
> going to loose this information now?

Would printing the number of sectors for each request help? If you
think this is really important we can keep this redundant information
as well.

>
> Vivek
>
>>       return slice_used;
>>  }
>>
>> @@ -917,8 +914,7 @@ static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
>>
>>       cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
>>                                       st->min_vdisktime);
>> -     blkiocg_update_blkio_group_stats(&cfqg->blkg, used_sl,
>> -                                             cfqq->nr_sectors);
>> +     blkiocg_update_blkio_group_stats(&cfqg->blkg, used_sl);
>>  }
>>
>>  #ifdef CONFIG_CFQ_GROUP_IOSCHED
>> @@ -1524,7 +1520,6 @@ static void __cfq_set_active_queue(struct cfq_data *cfqd,
>>               cfqq->allocated_slice = 0;
>>               cfqq->slice_end = 0;
>>               cfqq->slice_dispatch = 0;
>> -             cfqq->nr_sectors = 0;
>>
>>               cfq_clear_cfqq_wait_request(cfqq);
>>               cfq_clear_cfqq_must_dispatch(cfqq);
>> @@ -1869,7 +1864,6 @@ static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
>>       elv_dispatch_sort(q, rq);
>>
>>       cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
>> -     cfqq->nr_sectors += blk_rq_sectors(rq);
>>  }
>>
>>  /*
>
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