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| author | Tejun Heo <tj@kernel.org> | 2013-01-09 08:05:11 -0800 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2013-01-09 08:05:11 -0800 |
| commit | 41cad6ab2cb9ccb3b11546ad56b8b285e47c6279 (patch) | |
| tree | c6308080ab464a5f7a5da52035e948431061949a /block | |
| parent | 1d3650f713e7f6392b02fde450c5bae40291e65b (diff) | |
| download | lwn-41cad6ab2cb9ccb3b11546ad56b8b285e47c6279.tar.gz lwn-41cad6ab2cb9ccb3b11546ad56b8b285e47c6279.zip | |
cfq-iosched: convert cfq_group_slice() to use cfqg->vfraction
cfq_group_slice() calculates slice by taking a fraction of
cfq_target_latency according to the ratio of cfqg->weight against
service_tree->total_weight. This currently works only because all
cfqgs are treated to be at the same level.
To prepare for proper hierarchy support, convert cfq_group_slice() to
base the calculation on cfqg->vfraction. As cfqg->vfraction is always
a fraction of 1 and represents the fraction allocated to the cfqg with
hierarchy considered, the slice can be simply calculated by
multiplying cfqg->vfraction to cfq_target_latency (with fixed point
shift factored in).
As vfraction calculation currently treats all non-root cfqgs as
children of the root cfqg, this patch doesn't introduce noticeable
behavior difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Diffstat (limited to 'block')
| -rw-r--r-- | block/cfq-iosched.c | 7 |
1 files changed, 1 insertions, 6 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index b24acf66d5b5..ee342826fd98 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -85,7 +85,6 @@ struct cfq_rb_root { struct rb_root rb; struct rb_node *left; unsigned count; - unsigned total_weight; u64 min_vdisktime; struct cfq_ttime ttime; }; @@ -979,9 +978,7 @@ static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd, static inline unsigned cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg) { - struct cfq_rb_root *st = &cfqd->grp_service_tree; - - return cfqd->cfq_target_latency * cfqg->weight / st->total_weight; + return cfqd->cfq_target_latency * cfqg->vfraction >> CFQ_SERVICE_SHIFT; } static inline unsigned @@ -1273,7 +1270,6 @@ cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) cfq_update_group_weight(cfqg); __cfq_group_service_tree_add(st, cfqg); - st->total_weight += cfqg->weight; /* * Activate @cfqg and calculate the portion of vfraction @cfqg is @@ -1360,7 +1356,6 @@ cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg) } /* remove from the service tree */ - st->total_weight -= cfqg->weight; if (!RB_EMPTY_NODE(&cfqg->rb_node)) cfq_rb_erase(&cfqg->rb_node, st); } |