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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: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This commit is contained in:
Mike Snitzer 2010-03-06 02:32:33 +00:00 committed by Alasdair G Kergon
parent 3abf85b5b5
commit 924e600d41
2 changed files with 15 additions and 15 deletions
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26
drivers/md/dm-snap.c
View File

@ -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.

4
include/linux/dm-io.h
View File

@ -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 {