cfq: reorder cfq_queue removing padding on 64bit
Richard Kennedy [Mon, 22 Feb 2010 12:49:24 +0000 (13:49 +0100)]
This removes 8 bytes of padding from struct cfq_queue on 64 bit builds,
shrinking it's size to 256 bytes, so fitting into 1 fewer cachelines and
allowing 1 more object/slab in it's kmem_cache.

Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
----
patch against 2.6.33-rc8
tested on x86_64 AMDX2
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

block/cfq-iosched.c

index 023f4e6..e3dedfd 100644 (file)
@@ -115,11 +115,11 @@ struct cfq_queue {
        /* time when queue got scheduled in to dispatch first request. */
        unsigned long dispatch_start;
        unsigned int allocated_slice;
+       unsigned int slice_dispatch;
        /* time when first request from queue completed and slice started. */
        unsigned long slice_start;
        unsigned long slice_end;
        long slice_resid;
-       unsigned int slice_dispatch;
 
        /* pending metadata requests */
        int meta_pending;
@@ -130,13 +130,13 @@ struct cfq_queue {
        unsigned short ioprio, org_ioprio;
        unsigned short ioprio_class, org_ioprio_class;
 
+       pid_t pid;
+
        unsigned int seek_samples;
        u64 seek_total;
        sector_t seek_mean;
        sector_t last_request_pos;
 
-       pid_t pid;
-
        struct cfq_rb_root *service_tree;
        struct cfq_queue *new_cfqq;
        struct cfq_group *cfqg;