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authorAndi Kleen <ak@linux.intel.com>2011-08-01 21:38:06 -0700
committerroot <root@serles.lst.de>2011-10-28 14:58:57 +0200
commit6e8267f532a17165ab551ac5fdafcba5333dcca5 (patch)
tree7181c144b28f37d27275f74a538b01f891e149f7
parent0dc2bc49be545626a2dc6da133202ffe69ac3fcc (diff)
direct-io: use a slab cache for struct dio
A direct slab call is slightly faster than kmalloc and can be better cached per CPU. It also avoids rounding to the next kmalloc slab. In addition this enforces cache line alignment for struct dio to avoid any false sharing. Signed-off-by: Andi Kleen <ak@linux.intel.com> Acked-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
-rw-r--r--fs/direct-io.c19
1 files changed, 14 insertions, 5 deletions
diff --git a/fs/direct-io.c b/fs/direct-io.c
index b01ea0d7160d..6bb04409e725 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -140,7 +140,9 @@ struct dio {
* wish that they not be zeroed.
*/
struct page *pages[DIO_PAGES]; /* page buffer */
-};
+} ____cacheline_aligned_in_smp;
+
+static struct kmem_cache *dio_cache __read_mostly;
static void __inode_dio_wait(struct inode *inode)
{
@@ -330,7 +332,7 @@ static void dio_bio_end_aio(struct bio *bio, int error)
if (remaining == 0) {
dio_complete(dio, dio->iocb->ki_pos, 0, true);
- kfree(dio);
+ kmem_cache_free(dio_cache, dio);
}
}
@@ -1180,7 +1182,7 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode,
if (ret2 == 0) {
ret = dio_complete(dio, offset, ret, false);
- kfree(dio);
+ kmem_cache_free(dio_cache, dio);
} else
BUG_ON(ret != -EIOCBQUEUED);
@@ -1256,7 +1258,7 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
if (rw == READ && end == offset)
return 0;
- dio = kmalloc(sizeof(*dio), GFP_KERNEL);
+ dio = kmem_cache_alloc(dio_cache, GFP_KERNEL);
retval = -ENOMEM;
if (!dio)
goto out;
@@ -1280,7 +1282,7 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
end - 1);
if (retval) {
mutex_unlock(&inode->i_mutex);
- kfree(dio);
+ kmem_cache_free(dio_cache, dio);
goto out;
}
}
@@ -1308,3 +1310,10 @@ out:
return retval;
}
EXPORT_SYMBOL(__blockdev_direct_IO);
+
+static __init int dio_init(void)
+{
+ dio_cache = KMEM_CACHE(dio, SLAB_PANIC);
+ return 0;
+}
+module_init(dio_init)