Commit 611c3e16 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Mike Snitzer
Browse files

dm writecache: add optional "metadata_only" parameter 



Add a "metadata_only" parameter that when present: only metadata is
promoted to the cache. This option improves performance for heavier
REQ_META workloads (e.g. device-mapper-test-suite's "git clone and
checkout" benchmark improves from 341s to 312s).

Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent cd039afa

Documentation/admin-guide/device-mapper/writecache.rst

+3 −0
Original line number Diff line number Diff line
@@ -68,6 +68,9 @@ Constructor parameters: 
		specifies the maximum age of a block in milliseconds. If

		a block is stored in the cache for too long, it will be

		written to the underlying device and cleaned up.

	metadata_only

		only metadata is promoted to the cache. This option

		improves performance for heavier REQ_META workloads.



Status:

1. error indicator - 0 if there was no error, otherwise error number

drivers/md/dm-writecache.c

+12 −4
Original line number Diff line number Diff line
@@ -171,6 +171,7 @@ struct dm_writecache { 
	bool flush_on_suspend:1;

	bool cleaner:1;

	bool cleaner_set:1;

	bool metadata_only:1;



	unsigned high_wm_percent_value;

	unsigned low_wm_percent_value;
@@ -1301,7 +1302,7 @@ static int writecache_map(struct dm_target *ti, struct bio *bio) 
			writecache_flush(wc);

			if (writecache_has_error(wc))

				goto unlock_error;

			if (unlikely(wc->cleaner))

			if (unlikely(wc->cleaner) || unlikely(wc->metadata_only))

				goto unlock_remap_origin;

			goto unlock_submit;

		} else {
@@ -1380,7 +1381,8 @@ static int writecache_map(struct dm_target *ti, struct bio *bio) 
				}

				found_entry = true;

			} else {

				if (unlikely(wc->cleaner))

				if (unlikely(wc->cleaner) ||

				    (wc->metadata_only && !(bio->bi_opf & REQ_META)))

					goto direct_write;

			}

			e = writecache_pop_from_freelist(wc, (sector_t)-1);
@@ -2094,7 +2096,7 @@ static int writecache_ctr(struct dm_target *ti, unsigned argc, char **argv) 
	struct wc_memory_superblock s;



	static struct dm_arg _args[] = {

		{0, 16, "Invalid number of feature args"},

		{0, 17, "Invalid number of feature args"},

	};



	as.argc = argc;
@@ -2321,6 +2323,8 @@ static int writecache_ctr(struct dm_target *ti, unsigned argc, char **argv) 
				wc->writeback_fua = false;

				wc->writeback_fua_set = true;

			} else goto invalid_optional;

		} else if (!strcasecmp(string, "metadata_only")) {

			wc->metadata_only = true;

		} else {

invalid_optional:

			r = -EINVAL;
@@ -2544,6 +2548,8 @@ static void writecache_status(struct dm_target *ti, status_type_t type, 
			extra_args++;

		if (wc->writeback_fua_set)

			extra_args++;

		if (wc->metadata_only)

			extra_args++;



		DMEMIT("%u", extra_args);

		if (wc->start_sector_set)
@@ -2564,13 +2570,15 @@ static void writecache_status(struct dm_target *ti, status_type_t type, 
			DMEMIT(" cleaner");

		if (wc->writeback_fua_set)

			DMEMIT(" %sfua", wc->writeback_fua ? "" : "no");

		if (wc->metadata_only)

			DMEMIT(" metadata_only");

		break;

	}

}



static struct target_type writecache_target = {

	.name			= "writecache",

	.version		= {1, 4, 0},

	.version		= {1, 5, 0},

	.module			= THIS_MODULE,

	.ctr			= writecache_ctr,

	.dtr			= writecache_dtr,