blkcg: cfq doesn't need per-cpu dispatch stats

blkio_group_stats_cpu is used to count dispatch stats using per-cpu
counters.  This is used by both blk-throtl and cfq-iosched but the
sharing is rather silly.

* cfq-iosched doesn't need per-cpu dispatch stats.  cfq always updates
  those stats while holding queue_lock.

* blk-throtl needs per-cpu dispatch stats but only service_bytes and
  serviced.  It doesn't make use of sectors.

This patch makes cfq add and use global stats for service_bytes,
serviced and sectors, removes per-cpu sectors counter and moves
per-cpu stat printing code to blk-throttle.c.

Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 2 insertions, 61 deletions

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 821a0a393e85..19ee29f1b7c5 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -390,7 +390,6 @@ static void blkio_reset_stats_cpu(struct blkio_group *blkg, int plid)
 
                 blkg_rwstat_reset(&sc->service_bytes);
                 blkg_rwstat_reset(&sc->serviced);
-                blkg_stat_reset(&sc->sectors);
         }
 }
 
@@ -417,6 +416,8 @@ blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val)
                         struct blkio_group_stats *stats = &pd->stats;
 
                         /* queued stats shouldn't be cleared */
+                        blkg_rwstat_reset(&stats->service_bytes);
+                        blkg_rwstat_reset(&stats->serviced);
                         blkg_rwstat_reset(&stats->merged);
                         blkg_rwstat_reset(&stats->service_time);
                         blkg_rwstat_reset(&stats->wait_time);
@@ -577,66 +578,6 @@ int blkcg_print_rwstat(struct cgroup *cgrp, struct cftype *cft,
 }
 EXPORT_SYMBOL_GPL(blkcg_print_rwstat);
 
-static u64 blkg_prfill_cpu_stat(struct seq_file *sf,
-                                struct blkg_policy_data *pd, int off)
-{
-        u64 v = 0;
-        int cpu;
-
-        for_each_possible_cpu(cpu) {
-                struct blkio_group_stats_cpu *sc =
-                        per_cpu_ptr(pd->stats_cpu, cpu);
-
-                v += blkg_stat_read((void *)sc + off);
-        }
-
-        return __blkg_prfill_u64(sf, pd, v);
-}
-
-static u64 blkg_prfill_cpu_rwstat(struct seq_file *sf,
-                                  struct blkg_policy_data *pd, int off)
-{
-        struct blkg_rwstat rwstat = { }, tmp;
-        int i, cpu;
-
-        for_each_possible_cpu(cpu) {
-                struct blkio_group_stats_cpu *sc =
-                        per_cpu_ptr(pd->stats_cpu, cpu);
-
-                tmp = blkg_rwstat_read((void *)sc + off);
-                for (i = 0; i < BLKG_RWSTAT_NR; i++)
-                        rwstat.cnt[i] += tmp.cnt[i];
-        }
-
-        return __blkg_prfill_rwstat(sf, pd, &rwstat);
-}
-
-/* print per-cpu blkg_stat specified by BLKCG_STAT_PRIV() */
-int blkcg_print_cpu_stat(struct cgroup *cgrp, struct cftype *cft,
-                         struct seq_file *sf)
-{
-        struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);
-
-        blkcg_print_blkgs(sf, blkcg, blkg_prfill_cpu_stat,
-                          BLKCG_STAT_POL(cft->private),
-                          BLKCG_STAT_OFF(cft->private), false);
-        return 0;
-}
-EXPORT_SYMBOL_GPL(blkcg_print_cpu_stat);
-
-/* print per-cpu blkg_rwstat specified by BLKCG_STAT_PRIV() */
-int blkcg_print_cpu_rwstat(struct cgroup *cgrp, struct cftype *cft,
-                           struct seq_file *sf)
-{
-        struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);
-
-        blkcg_print_blkgs(sf, blkcg, blkg_prfill_cpu_rwstat,
-                          BLKCG_STAT_POL(cft->private),
-                          BLKCG_STAT_OFF(cft->private), true);
-        return 0;
-}
-EXPORT_SYMBOL_GPL(blkcg_print_cpu_rwstat);
-
 /**
  * blkg_conf_prep - parse and prepare for per-blkg config update
  * @blkcg: target block cgroup