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authorTejun Heo <tj@kernel.org>2015-08-18 14:55:34 -0700
committerJens Axboe <axboe@fb.com>2015-08-18 15:49:35 -0700
commit2ee867dcfa2eaef1063b686da55c35878b2da4a2 (patch)
tree7f2babb38e525ce07394042d5dc019e61a46f50c /block/blk-cgroup.c
parentdd165eb3bb4ef16bcdb75417add40633f38c52b8 (diff)
downloadlwn-2ee867dcfa2eaef1063b686da55c35878b2da4a2.tar.gz
lwn-2ee867dcfa2eaef1063b686da55c35878b2da4a2.zip
blkcg: implement interface for the unified hierarchy
blkcg interface grew to be the biggest of all controllers and unfortunately most inconsistent too. The interface files are inconsistent with a number of cloes duplicates. Some files have recursive variants while others don't. There's distinction between normal and leaf weights which isn't intuitive and there are a lot of stat knobs which don't make much sense outside of debugging and expose too much implementation details to userland. In the unified hierarchy, everything is always hierarchical and internal nodes can't have tasks rendering the two structural issues twisting the current interface. The interface has to be updated in a significant anyway and this is a good chance to revamp it as a whole. This patch implements blkcg interface for the unified hierarchy. * (from a previous patch) blkcg is identified by "io" instead of "blkio" on the unified hierarchy. Given that the whole interface is updated anyway, the rename shouldn't carry noticeable conversion overhead. * The original interface consisted of 27 files is replaced with the following three files. blkio.stat : per-blkcg stats blkio.weight : per-cgroup and per-cgroup-queue weight settings blkio.max : per-cgroup-queue bps and iops max limits Documentation/cgroups/unified-hierarchy.txt updated accordingly. v2: blkcg_policy->dfl_cftypes wasn't removed on blkcg_policy_unregister() corrupting the cftypes list. Fixed. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block/blk-cgroup.c')
-rw-r--r--block/blk-cgroup.c53
1 files changed, 53 insertions, 0 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index b5e72d756be1..88bdb73bd5e0 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -854,6 +854,53 @@ void blkg_conf_finish(struct blkg_conf_ctx *ctx)
}
EXPORT_SYMBOL_GPL(blkg_conf_finish);
+static int blkcg_print_stat(struct seq_file *sf, void *v)
+{
+ struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
+ struct blkcg_gq *blkg;
+
+ rcu_read_lock();
+
+ hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) {
+ const char *dname;
+ struct blkg_rwstat rwstat;
+ u64 rbytes, wbytes, rios, wios;
+
+ dname = blkg_dev_name(blkg);
+ if (!dname)
+ continue;
+
+ spin_lock_irq(blkg->q->queue_lock);
+
+ rwstat = blkg_rwstat_recursive_sum(blkg, NULL,
+ offsetof(struct blkcg_gq, stat_bytes));
+ rbytes = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_READ]);
+ wbytes = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_WRITE]);
+
+ rwstat = blkg_rwstat_recursive_sum(blkg, NULL,
+ offsetof(struct blkcg_gq, stat_ios));
+ rios = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_READ]);
+ wios = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_WRITE]);
+
+ spin_unlock_irq(blkg->q->queue_lock);
+
+ if (rbytes || wbytes || rios || wios)
+ seq_printf(sf, "%s rbytes=%llu wbytes=%llu rios=%llu wios=%llu\n",
+ dname, rbytes, wbytes, rios, wios);
+ }
+
+ rcu_read_unlock();
+ return 0;
+}
+
+struct cftype blkcg_files[] = {
+ {
+ .name = "stat",
+ .seq_show = blkcg_print_stat,
+ },
+ { } /* terminate */
+};
+
struct cftype blkcg_legacy_files[] = {
{
.name = "reset_stats",
@@ -1101,6 +1148,7 @@ struct cgroup_subsys io_cgrp_subsys = {
.css_offline = blkcg_css_offline,
.css_free = blkcg_css_free,
.can_attach = blkcg_can_attach,
+ .dfl_cftypes = blkcg_files,
.legacy_cftypes = blkcg_legacy_files,
.legacy_name = "blkio",
#ifdef CONFIG_MEMCG
@@ -1273,6 +1321,9 @@ int blkcg_policy_register(struct blkcg_policy *pol)
mutex_unlock(&blkcg_pol_mutex);
/* everything is in place, add intf files for the new policy */
+ if (pol->dfl_cftypes)
+ WARN_ON(cgroup_add_dfl_cftypes(&io_cgrp_subsys,
+ pol->dfl_cftypes));
if (pol->legacy_cftypes)
WARN_ON(cgroup_add_legacy_cftypes(&io_cgrp_subsys,
pol->legacy_cftypes));
@@ -1312,6 +1363,8 @@ void blkcg_policy_unregister(struct blkcg_policy *pol)
goto out_unlock;
/* kill the intf files first */
+ if (pol->dfl_cftypes)
+ cgroup_rm_cftypes(pol->dfl_cftypes);
if (pol->legacy_cftypes)
cgroup_rm_cftypes(pol->legacy_cftypes);