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Date: Tue, 14 Dec 2010 09:33:11 +0800
From: Gui Jianfeng <guijianfeng@...fujitsu.com>
To: Vivek Goyal <vgoyal@...hat.com>
CC: Jens Axboe <axboe@...nel.dk>, Corrado Zoccolo <czoccolo@...il.com>,
Chad Talbott <ctalbott@...gle.com>,
Nauman Rafique <nauman@...gle.com>,
Divyesh Shah <dpshah@...gle.com>,
linux kernel mailing list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/8 v2] cfq-iosched: Introduce cfq_entity for CFQ group
Vivek Goyal wrote:
> On Mon, Dec 13, 2010 at 09:44:33AM +0800, Gui Jianfeng wrote:
>> Introduce cfq_entity for CFQ group
>>
>> Signed-off-by: Gui Jianfeng <guijianfeng@...fujitsu.com>
>> ---
>> block/cfq-iosched.c | 113 ++++++++++++++++++++++++++++++--------------------
>> 1 files changed, 68 insertions(+), 45 deletions(-)
>>
>> diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
>> index 9b07a24..91e9833 100644
>> --- a/block/cfq-iosched.c
>> +++ b/block/cfq-iosched.c
>> @@ -1,5 +1,5 @@
>> /*
>> - * CFQ, or complete fairness queueing, disk scheduler.
>> + * Cfq, or complete fairness queueing, disk scheduler.
>
> Is this really required?
>
>> *
>> * Based on ideas from a previously unfinished io
>> * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
>> @@ -73,7 +73,8 @@ static DEFINE_IDA(cic_index_ida);
>> #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
>>
>> #define sample_valid(samples) ((samples) > 80)
>> -#define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
>> +#define rb_entry_entity(node) rb_entry((node), struct cfq_entity,\
>> + rb_node)
>>
>> /*
>> * Most of our rbtree usage is for sorting with min extraction, so
>> @@ -102,6 +103,11 @@ struct cfq_entity {
>> struct rb_node rb_node;
>> /* service_tree key, represent the position on the tree */
>> unsigned long rb_key;
>> +
>> + /* group service_tree key */
>> + u64 vdisktime;
>> + bool is_group_entity;
>> + unsigned int weight;
>> };
>>
>> /*
>> @@ -183,12 +189,8 @@ enum wl_type_t {
>>
>> /* This is per cgroup per device grouping structure */
>> struct cfq_group {
>> - /* group service_tree member */
>> - struct rb_node rb_node;
>> -
>> - /* group service_tree key */
>> - u64 vdisktime;
>> - unsigned int weight;
>> + /* cfq group sched entity */
>> + struct cfq_entity cfqe;
>>
>> /* number of cfqq currently on this group */
>> int nr_cfqq;
>> @@ -315,12 +317,21 @@ struct cfq_data {
>> static inline struct cfq_queue *
>> cfqq_of_entity(struct cfq_entity *cfqe)
>> {
>> - if (cfqe)
>> + if (cfqe && !cfqe->is_group_entity)
>> return container_of(cfqe, struct cfq_queue,
>> cfqe);
>
> can be single line above. I think came from previous patch.
>
>> return NULL;
>> }
>>
>> +static inline struct cfq_group *
>> +cfqg_of_entity(struct cfq_entity *cfqe)
>> +{
>> + if (cfqe && cfqe->is_group_entity)
>> + return container_of(cfqe, struct cfq_group,
>> + cfqe);
>
> No need to split line.
>
>> + return NULL;
>> +}
>> +
>> static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
>>
>> static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
>> @@ -548,12 +559,12 @@ cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
>> return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
>> }
>>
>> -static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
>> +static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_entity *cfqe)
>> {
>> u64 d = delta << CFQ_SERVICE_SHIFT;
>>
>> d = d * BLKIO_WEIGHT_DEFAULT;
>> - do_div(d, cfqg->weight);
>> + do_div(d, cfqe->weight);
>> return d;
>> }
>>
>> @@ -578,11 +589,11 @@ static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
>> static void update_min_vdisktime(struct cfq_rb_root *st)
>> {
>> u64 vdisktime = st->min_vdisktime;
>> - struct cfq_group *cfqg;
>> + struct cfq_entity *cfqe;
>>
>> if (st->left) {
>> - cfqg = rb_entry_cfqg(st->left);
>> - vdisktime = min_vdisktime(vdisktime, cfqg->vdisktime);
>> + cfqe = rb_entry_entity(st->left);
>> + vdisktime = min_vdisktime(vdisktime, cfqe->vdisktime);
>> }
>>
>> st->min_vdisktime = max_vdisktime(st->min_vdisktime, vdisktime);
>> @@ -613,8 +624,9 @@ static inline unsigned
>> cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
>> {
>> struct cfq_rb_root *st = &cfqd->grp_service_tree;
>> + struct cfq_entity *cfqe = &cfqg->cfqe;
>>
>> - return cfq_target_latency * cfqg->weight / st->total_weight;
>> + return cfq_target_latency * cfqe->weight / st->total_weight;
>> }
>>
>> static inline void
>> @@ -777,13 +789,13 @@ static struct cfq_entity *cfq_rb_first(struct cfq_rb_root *root)
>> return NULL;
>> }
>>
>> -static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
>> +static struct cfq_entity *cfq_rb_first_entity(struct cfq_rb_root *root)
>
> So now we have two functions. One cfq_rb_first() and one cfq_rb_first_entity()
> both returning cfq_entity*? This is confusing. Or you are getting rid of
> one in later patches. Why not make use of existing cfq_rb_first()?
Yes, I get rid of cfq_rb_first_entity() in later patch.
Thanks,
Gui
>
> Thanks
> Vivek
>
--
Regards
Gui Jianfeng
--
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