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Commit 924e600d authored by Mike Snitzer's avatar Mike Snitzer Committed by Alasdair G Kergon
Browse files

dm: eliminate some holes data structures 



Eliminate a 4-byte hole in 'struct dm_io_memory' by moving 'offset' above the
'ptr' to which it applies (size reduced from 24 to 16 bytes).  And by
association, 1-4 byte hole is eliminated in 'struct dm_io_request' (size
reduced from 56 to 48 bytes).

Eliminate all 6 4-byte holes and 1 cache-line in 'struct dm_snapshot' (size
reduced from 392 to 368 bytes).

Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent 3abf85b5

drivers/md/dm-snap.c

+13 −13
Original line number Diff line number Diff line
@@ -83,10 +83,10 @@ struct dm_snapshot { 
	/* Whether or not owning mapped_device is suspended */

	int suspended;



	mempool_t *pending_pool;



	atomic_t pending_exceptions_count;



	mempool_t *pending_pool;



	struct dm_exception_table pending;

	struct dm_exception_table complete;
@@ -96,6 +96,11 @@ struct dm_snapshot { 
	 */

	spinlock_t pe_lock;



	/* Chunks with outstanding reads */

	spinlock_t tracked_chunk_lock;

	mempool_t *tracked_chunk_pool;

	struct hlist_head tracked_chunk_hash[DM_TRACKED_CHUNK_HASH_SIZE];



	/* The on disk metadata handler */

	struct dm_exception_store *store;
@@ -105,10 +110,12 @@ struct dm_snapshot { 
	struct bio_list queued_bios;

	struct work_struct queued_bios_work;



	/* Chunks with outstanding reads */

	mempool_t *tracked_chunk_pool;

	spinlock_t tracked_chunk_lock;

	struct hlist_head tracked_chunk_hash[DM_TRACKED_CHUNK_HASH_SIZE];

	/* Wait for events based on state_bits */

	unsigned long state_bits;



	/* Range of chunks currently being merged. */

	chunk_t first_merging_chunk;

	int num_merging_chunks;



	/*

	 * The merge operation failed if this flag is set.
@@ -125,13 +132,6 @@ struct dm_snapshot { 
	 */

	int merge_failed;



	/* Wait for events based on state_bits */

	unsigned long state_bits;



	/* Range of chunks currently being merged. */

	chunk_t first_merging_chunk;

	int num_merging_chunks;



	/*

	 * Incoming bios that overlap with chunks being merged must wait

	 * for them to be committed.

include/linux/dm-io.h

+2 −2
Original line number Diff line number Diff line
@@ -37,14 +37,14 @@ enum dm_io_mem_type { 
struct dm_io_memory {

	enum dm_io_mem_type type;



	unsigned offset;



	union {

		struct page_list *pl;

		struct bio_vec *bvec;

		void *vma;

		void *addr;

	} ptr;



	unsigned offset;

};



struct dm_io_notify {