From 24bdb8ef068ebdc2a57ce715f0ab22d5da32832a Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 18 Aug 2015 14:55:22 -0700 Subject: blkcg: make blkcg_[rw]stat per-cpu blkcg_[rw]stat are used as stat counters for blkcg policies. It isn't per-cpu by itself and blk-throttle makes it per-cpu by wrapping around it. This patch makes blkcg_[rw]stat per-cpu and drop the ad-hoc per-cpu wrapping in blk-throttle. * blkg_[rw]stat->cnt is replaced with cpu_cnt which is struct percpu_counter. This makes syncp unnecessary as remote accesses are handled by percpu_counter itself. * blkg_[rw]stat_init() can now fail due to percpu allocation failure and thus are updated to return int. * percpu_counters need explicit freeing. blkg_[rw]stat_exit() added. * As blkg_rwstat->cpu_cnt[] can't be read directly anymore, reading and summing results are stored in ->aux_cnt[] instead. * Custom per-cpu stat implementation in blk-throttle is removed. This makes all blkcg stat counters per-cpu without complicating policy implmentations. Signed-off-by: Tejun Heo Cc: Vivek Goyal Signed-off-by: Jens Axboe --- block/blk-throttle.c | 89 +++++++++++++++++----------------------------------- 1 file changed, 28 insertions(+), 61 deletions(-) (limited to 'block/blk-throttle.c') diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 29c22ed..c0b2263 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -83,14 +83,6 @@ enum tg_state_flags { #define rb_entry_tg(node) rb_entry((node), struct throtl_grp, rb_node) -/* Per-cpu group stats */ -struct tg_stats_cpu { - /* total bytes transferred */ - struct blkg_rwstat service_bytes; - /* total IOs serviced, post merge */ - struct blkg_rwstat serviced; -}; - struct throtl_grp { /* must be the first member */ struct blkg_policy_data pd; @@ -142,8 +134,10 @@ struct throtl_grp { unsigned long slice_start[2]; unsigned long slice_end[2]; - /* Per cpu stats pointer */ - struct tg_stats_cpu __percpu *stats_cpu; + /* total bytes transferred */ + struct blkg_rwstat service_bytes; + /* total IOs serviced, post merge */ + struct blkg_rwstat serviced; }; struct throtl_data @@ -337,17 +331,15 @@ static void throtl_service_queue_init(struct throtl_service_queue *sq) static struct blkg_policy_data *throtl_pd_alloc(gfp_t gfp, int node) { struct throtl_grp *tg; - int rw, cpu; + int rw; tg = kzalloc_node(sizeof(*tg), gfp, node); if (!tg) - return NULL; + goto err; - tg->stats_cpu = alloc_percpu_gfp(struct tg_stats_cpu, gfp); - if (!tg->stats_cpu) { - kfree(tg); - return NULL; - } + if (blkg_rwstat_init(&tg->service_bytes, gfp) || + blkg_rwstat_init(&tg->serviced, gfp)) + goto err_free_tg; throtl_service_queue_init(&tg->service_queue); @@ -362,14 +354,14 @@ static struct blkg_policy_data *throtl_pd_alloc(gfp_t gfp, int node) tg->iops[READ] = -1; tg->iops[WRITE] = -1; - for_each_possible_cpu(cpu) { - struct tg_stats_cpu *stats_cpu = per_cpu_ptr(tg->stats_cpu, cpu); - - blkg_rwstat_init(&stats_cpu->service_bytes); - blkg_rwstat_init(&stats_cpu->serviced); - } - return &tg->pd; + +err_free_tg: + blkg_rwstat_exit(&tg->serviced); + blkg_rwstat_exit(&tg->service_bytes); + kfree(tg); +err: + return NULL; } static void throtl_pd_init(struct blkg_policy_data *pd) @@ -427,21 +419,17 @@ static void throtl_pd_free(struct blkg_policy_data *pd) struct throtl_grp *tg = pd_to_tg(pd); del_timer_sync(&tg->service_queue.pending_timer); - free_percpu(tg->stats_cpu); + blkg_rwstat_exit(&tg->serviced); + blkg_rwstat_exit(&tg->service_bytes); kfree(tg); } static void throtl_pd_reset_stats(struct blkg_policy_data *pd) { struct throtl_grp *tg = pd_to_tg(pd); - int cpu; - for_each_possible_cpu(cpu) { - struct tg_stats_cpu *sc = per_cpu_ptr(tg->stats_cpu, cpu); - - blkg_rwstat_reset(&sc->service_bytes); - blkg_rwstat_reset(&sc->serviced); - } + blkg_rwstat_reset(&tg->service_bytes); + blkg_rwstat_reset(&tg->serviced); } static struct throtl_grp * @@ -855,7 +843,6 @@ static void throtl_update_dispatch_stats(struct blkcg_gq *blkg, u64 bytes, int rw) { struct throtl_grp *tg = blkg_to_tg(blkg); - struct tg_stats_cpu *stats_cpu; unsigned long flags; /* @@ -865,10 +852,8 @@ static void throtl_update_dispatch_stats(struct blkcg_gq *blkg, u64 bytes, */ local_irq_save(flags); - stats_cpu = this_cpu_ptr(tg->stats_cpu); - - blkg_rwstat_add(&stats_cpu->serviced, rw, 1); - blkg_rwstat_add(&stats_cpu->service_bytes, rw, bytes); + blkg_rwstat_add(&tg->serviced, rw, 1); + blkg_rwstat_add(&tg->service_bytes, rw, bytes); local_irq_restore(flags); } @@ -1176,27 +1161,9 @@ static void blk_throtl_dispatch_work_fn(struct work_struct *work) } } -static u64 tg_prfill_cpu_rwstat(struct seq_file *sf, - struct blkg_policy_data *pd, int off) -{ - struct throtl_grp *tg = pd_to_tg(pd); - struct blkg_rwstat rwstat = { }, tmp; - int i, cpu; - - for_each_possible_cpu(cpu) { - struct tg_stats_cpu *sc = per_cpu_ptr(tg->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); -} - -static int tg_print_cpu_rwstat(struct seq_file *sf, void *v) +static int tg_print_rwstat(struct seq_file *sf, void *v) { - blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_cpu_rwstat, + blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat, &blkcg_policy_throtl, seq_cft(sf)->private, true); return 0; } @@ -1337,13 +1304,13 @@ static struct cftype throtl_files[] = { }, { .name = "throttle.io_service_bytes", - .private = offsetof(struct tg_stats_cpu, service_bytes), - .seq_show = tg_print_cpu_rwstat, + .private = offsetof(struct throtl_grp, service_bytes), + .seq_show = tg_print_rwstat, }, { .name = "throttle.io_serviced", - .private = offsetof(struct tg_stats_cpu, serviced), - .seq_show = tg_print_cpu_rwstat, + .private = offsetof(struct throtl_grp, serviced), + .seq_show = tg_print_rwstat, }, { } /* terminate */ }; -- cgit v1.1