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SubjectRe: [PATCH v2] cfq: reorder cfq_queue removing padding on 64bit & allowing more objects/slab in it's kmem_cache
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 <>
patch against 2.6.33-rc8
tested on x86_64 AMDX2

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 023f4e6..e3dedfd 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -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;

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