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Date: Mon, 13 Dec 2010 11:59:26 -0500
From: Vivek Goyal <vgoyal@...hat.com>
To: Gui Jianfeng <guijianfeng@...fujitsu.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
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()?
Thanks
Vivek
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