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Commit 636620b6 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

blkcg: Track DISCARD statistics and output them in cgroup io.stat 



Add tracking of REQ_OP_DISCARD ios to the per-cgroup io.stat.  Two
fields, dbytes and dios, to respectively count the total bytes and
number of discards are added.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Andy Newell <newella@fb.com>
Cc: Michael Callahan <michaelcallahan@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent bdca3c87

Documentation/admin-guide/cgroup-v2.rst

+6 −4
Original line number Diff line number Diff line
@@ -1317,17 +1317,19 @@ IO Interface Files 
	Lines are keyed by $MAJ:$MIN device numbers and not ordered.

	The following nested keys are defined.



	  ======	===================

	  ======	=====================

	  rbytes	Bytes read

	  wbytes	Bytes written

	  rios		Number of read IOs

	  wios		Number of write IOs

	  ======	===================

	  dbytes	Bytes discarded

	  dios		Number of discard IOs

	  ======	=====================



	An example read output follows:



	  8:16 rbytes=1459200 wbytes=314773504 rios=192 wios=353

	  8:0 rbytes=90430464 wbytes=299008000 rios=8950 wios=1252

	  8:16 rbytes=1459200 wbytes=314773504 rios=192 wios=353 dbytes=0 dios=0

	  8:0 rbytes=90430464 wbytes=299008000 rios=8950 wios=1252 dbytes=50331648 dios=3021



  io.weight

	A read-write flat-keyed file which exists on non-root cgroups.

block/blk-cgroup.c

+9 −4
Original line number Diff line number Diff line
@@ -567,6 +567,7 @@ u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, 
		[BLKG_RWSTAT_WRITE]	= "Write",

		[BLKG_RWSTAT_SYNC]	= "Sync",

		[BLKG_RWSTAT_ASYNC]	= "Async",

		[BLKG_RWSTAT_DISCARD]	= "Discard",

	};

	const char *dname = blkg_dev_name(pd->blkg);

	u64 v;
@@ -580,7 +581,8 @@ u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, 
			   (unsigned long long)atomic64_read(&rwstat->aux_cnt[i]));



	v = atomic64_read(&rwstat->aux_cnt[BLKG_RWSTAT_READ]) +

		atomic64_read(&rwstat->aux_cnt[BLKG_RWSTAT_WRITE]);

		atomic64_read(&rwstat->aux_cnt[BLKG_RWSTAT_WRITE]) +

		atomic64_read(&rwstat->aux_cnt[BLKG_RWSTAT_DISCARD]);

	seq_printf(sf, "%s Total %llu\n", dname, (unsigned long long)v);

	return v;

}
@@ -959,7 +961,7 @@ static int blkcg_print_stat(struct seq_file *sf, void *v) 
		const char *dname;

		char *buf;

		struct blkg_rwstat rwstat;

		u64 rbytes, wbytes, rios, wios;

		u64 rbytes, wbytes, rios, wios, dbytes, dios;

		size_t size = seq_get_buf(sf, &buf), off = 0;

		int i;

		bool has_stats = false;
@@ -982,19 +984,22 @@ static int blkcg_print_stat(struct seq_file *sf, void *v) 
					offsetof(struct blkcg_gq, stat_bytes));

		rbytes = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_READ]);

		wbytes = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_WRITE]);

		dbytes = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_DISCARD]);



		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]);

		dios = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_DISCARD]);



		spin_unlock_irq(blkg->q->queue_lock);



		if (rbytes || wbytes || rios || wios) {

			has_stats = true;

			off += scnprintf(buf+off, size-off,

					 "rbytes=%llu wbytes=%llu rios=%llu wios=%llu",

					 rbytes, wbytes, rios, wios);

					 "rbytes=%llu wbytes=%llu rios=%llu wios=%llu dbytes=%llu dios=%llu",

					 rbytes, wbytes, rios, wios,

					 dbytes, dios);

		}



		if (!blkcg_debug_stats)

include/linux/blk-cgroup.h

+4 −1
Original line number Diff line number Diff line
@@ -35,6 +35,7 @@ enum blkg_rwstat_type { 
	BLKG_RWSTAT_WRITE,

	BLKG_RWSTAT_SYNC,

	BLKG_RWSTAT_ASYNC,

	BLKG_RWSTAT_DISCARD,



	BLKG_RWSTAT_NR,

	BLKG_RWSTAT_TOTAL = BLKG_RWSTAT_NR,
@@ -649,7 +650,9 @@ static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat, 
{

	struct percpu_counter *cnt;



	if (op_is_write(op))

	if (op_is_discard(op))

		cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_DISCARD];

	else if (op_is_write(op))

		cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_WRITE];

	else

		cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_READ];