2005-10-13 19:13:29

by Chen, Kenneth W

Subject: [patch] remove gendisk->stamp_idle field

struct gendisk has these two fields: stamp, stamp_idle. Update to
stamp_idle is always in sync with stamp and they are always the same.
Therefore, it does not add any value in having two fields tracking
same timestamp. Suggest to remove it.

Also, we should only update gendisk stats with non-zero value.
Advantage is that we don't have to needlessly calculate memory address,
and then add zero to the content.


Signed-off-by: Ken Chen <[email protected]>

--- ./drivers/block/ll_rw_blk.c.orig 2005-10-13 11:47:02.265928213 -0700
+++ ./drivers/block/ll_rw_blk.c 2005-10-13 11:50:22.289363262 -0700
@@ -2433,13 +2433,12 @@ void disk_round_stats(struct gendisk *di
{
unsigned long now = jiffies;

- __disk_stat_add(disk, time_in_queue,
- disk->in_flight * (now - disk->stamp));
+ if (disk->in_flight) {
+ __disk_stat_add(disk, time_in_queue,
+ disk->in_flight * (now - disk->stamp));
+ __disk_stat_add(disk, io_ticks, (now - disk->stamp));
+ }
disk->stamp = now;
-
- if (disk->in_flight)
- __disk_stat_add(disk, io_ticks, (now - disk->stamp_idle));
- disk->stamp_idle = now;
}

/*
--- ./fs/partitions/check.c.orig 2005-10-13 11:52:09.186822890 -0700
+++ ./fs/partitions/check.c 2005-10-13 11:52:41.332330309 -0700
@@ -430,7 +430,7 @@ void del_gendisk(struct gendisk *disk)
disk->flags &= ~GENHD_FL_UP;
unlink_gendisk(disk);
disk_stat_set_all(disk, 0);
- disk->stamp = disk->stamp_idle = 0;
+ disk->stamp = 0;

devfs_remove_disk(disk);

--- ./include/linux/genhd.h.orig 2005-10-13 11:51:24.137995317 -0700
+++ ./include/linux/genhd.h 2005-10-13 11:51:43.293268520 -0700
@@ -119,7 +119,7 @@ struct gendisk {
int policy;

atomic_t sync_io; /* RAID */
- unsigned long stamp, stamp_idle;
+ unsigned long stamp;
int in_flight;
#ifdef CONFIG_SMP
struct disk_stats *dkstats;

2005-10-13 19:16:03

by Jens Axboe

Subject: Re: [patch] remove gendisk->stamp_idle field

On Thu, Oct 13 2005, Chen, Kenneth W wrote:
> struct gendisk has these two fields: stamp, stamp_idle. Update to
> stamp_idle is always in sync with stamp and they are always the same.
> Therefore, it does not add any value in having two fields tracking
> same timestamp. Suggest to remove it.
>
> Also, we should only update gendisk stats with non-zero value.
> Advantage is that we don't have to needlessly calculate memory address,
> and then add zero to the content.

Acked-by: Jens Axboe <[email protected]>

Added to the upstream Linus branch of the block git tree.

--
Jens Axboe