| Message ID | Pine.LNX.4.64.0902042148070.8695@hs20-bc2-1.build.redhat.com (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Delegated to: | Alasdair Kergon |
| Headers | show |
Reviewed-but-not-tested-by: Jonathan Brassow <jbrassow@redhat.com> brassow On Feb 4, 2009, at 8:53 PM, Mikulas Patocka wrote: > With my previous patch to save bio vector, the size of > dm_raid1_read_record > is significantly increased (the vector list takes 3072 bytes on 32- > bit machines > and 4096 bytes on 64-bit machines). > > The structure dm_raid1_read_record used to be allocated with kmalloc, > but kmalloc aligns the size on the next power-of-two --- so an object > slightly greater than 4096 will allocate 8192 bytes of memory and > half of > that memory will be wasted. > > This patch turns kmalloc into a slab cache. Slab cache doesn't have > this > padding, so it will reduce memory consumption per-request. > > Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> > > --- > drivers/md/dm-raid1.c | 24 ++++++++++++++++++++---- > 1 file changed, 20 insertions(+), 4 deletions(-) > > Index: linux-2.6.29-rc3-devel/drivers/md/dm-raid1.c > =================================================================== > --- linux-2.6.29-rc3-devel.orig/drivers/md/dm-raid1.c 2009-02-05 > 03:26:25.000000000 +0100 > +++ linux-2.6.29-rc3-devel/drivers/md/dm-raid1.c 2009-02-05 > 03:33:54.000000000 +0100 > @@ -145,6 +145,8 @@ struct dm_raid1_read_record { > struct dm_bio_details details; > }; > > +static struct kmem_cache *_dm_raid1_read_record_cache; > + > /* > * Every mirror should look like this one. > */ > @@ -764,9 +766,8 @@ static struct mirror_set *alloc_context( > atomic_set(&ms->suspend, 0); > atomic_set(&ms->default_mirror, DEFAULT_MIRROR); > > - len = sizeof(struct dm_raid1_read_record); > - ms->read_record_pool = mempool_create_kmalloc_pool(MIN_READ_RECORDS, > - len); > + ms->read_record_pool = mempool_create_slab_pool(MIN_READ_RECORDS, > _dm_raid1_read_record_cache); > + > if (!ms->read_record_pool) { > ti->error = "Error creating mirror read_record_pool"; > kfree(ms); > @@ -1279,16 +1280,31 @@ static int __init dm_mirror_init(void) > { > int r; > > + _dm_raid1_read_record_cache = KMEM_CACHE(dm_raid1_read_record, 0); > + if (!_dm_raid1_read_record_cache) { > + DMERR("Can't allocate dm_raid1_read_record cache"); > + r = -ENOMEM; > + goto bad_cache; > + } > + > r = dm_register_target(&mirror_target); > - if (r < 0) > + if (r < 0) { > DMERR("Failed to register mirror target"); > + goto bad_target; > + } > + > + return 0; > > +bad_target: > + kmem_cache_destroy(_dm_raid1_read_record_cache); > +bad_cache: > return r; > } > > static void __exit dm_mirror_exit(void) > { > dm_unregister_target(&mirror_target); > + kmem_cache_destroy(_dm_raid1_read_record_cache); > } > > /* Module hooks */ > > -- > dm-devel mailing list > dm-devel@redhat.com > https://www.redhat.com/mailman/listinfo/dm-devel -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
Index: linux-2.6.29-rc3-devel/drivers/md/dm-raid1.c =================================================================== --- linux-2.6.29-rc3-devel.orig/drivers/md/dm-raid1.c 2009-02-05 03:26:25.000000000 +0100 +++ linux-2.6.29-rc3-devel/drivers/md/dm-raid1.c 2009-02-05 03:33:54.000000000 +0100 @@ -145,6 +145,8 @@ struct dm_raid1_read_record { struct dm_bio_details details; }; +static struct kmem_cache *_dm_raid1_read_record_cache; + /* * Every mirror should look like this one. */ @@ -764,9 +766,8 @@ static struct mirror_set *alloc_context( atomic_set(&ms->suspend, 0); atomic_set(&ms->default_mirror, DEFAULT_MIRROR); - len = sizeof(struct dm_raid1_read_record); - ms->read_record_pool = mempool_create_kmalloc_pool(MIN_READ_RECORDS, - len); + ms->read_record_pool = mempool_create_slab_pool(MIN_READ_RECORDS, _dm_raid1_read_record_cache); + if (!ms->read_record_pool) { ti->error = "Error creating mirror read_record_pool"; kfree(ms); @@ -1279,16 +1280,31 @@ static int __init dm_mirror_init(void) { int r; + _dm_raid1_read_record_cache = KMEM_CACHE(dm_raid1_read_record, 0); + if (!_dm_raid1_read_record_cache) { + DMERR("Can't allocate dm_raid1_read_record cache"); + r = -ENOMEM; + goto bad_cache; + } + r = dm_register_target(&mirror_target); - if (r < 0) + if (r < 0) { DMERR("Failed to register mirror target"); + goto bad_target; + } + + return 0; +bad_target: + kmem_cache_destroy(_dm_raid1_read_record_cache); +bad_cache: return r; } static void __exit dm_mirror_exit(void) { dm_unregister_target(&mirror_target); + kmem_cache_destroy(_dm_raid1_read_record_cache); } /* Module hooks */
With my previous patch to save bio vector, the size of dm_raid1_read_record is significantly increased (the vector list takes 3072 bytes on 32-bit machines and 4096 bytes on 64-bit machines). The structure dm_raid1_read_record used to be allocated with kmalloc, but kmalloc aligns the size on the next power-of-two --- so an object slightly greater than 4096 will allocate 8192 bytes of memory and half of that memory will be wasted. This patch turns kmalloc into a slab cache. Slab cache doesn't have this padding, so it will reduce memory consumption per-request. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> --- drivers/md/dm-raid1.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel