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md: raid0: remove ->sectors from the strip_zone structure. 

storing ->sectors is redundant as is can be computed from the
difference  z->zone_end - (z-1)->zone_end

The one place where it is used, it is just as efficient to use
a zone_end value instead.

And removing it makes strip_zone smaller, so they array of these that
is searched on every request has a better chance to say in cache.

So discard the field and get the value from elsewhere.

Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
NeilBrown 2009-06-16 16:50:35 +10:00
parent fb5ab4b5d6
commit 49f357a22b
2 changed files with 19 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
drivers/md/raid0.c
View File

@ -55,7 +55,7 @@ static int raid0_congested(void *data, int bits)
static int create_strip_zones(mddev_t *mddev)
{
int i, c, j, err;
sector_t curr_zone_end;
sector_t curr_zone_end, sectors;
mdk_rdev_t *smallest, *rdev1, *rdev2, *rdev;
struct strip_zone *zone;
int cnt;
@ -153,10 +153,9 @@ static int create_strip_zones(mddev_t *mddev)
goto abort;
}
zone->nb_dev = cnt;
zone->sectors = smallest->sectors * cnt;
zone->zone_end = zone->sectors;
zone->zone_end = smallest->sectors * cnt;
curr_zone_end = zone->sectors;
curr_zone_end = zone->zone_end;
/* now do the other zones */
for (i = 1; i < conf->nr_strip_zones; i++)
@ -189,11 +188,11 @@ static int create_strip_zones(mddev_t *mddev)
}
zone->nb_dev = c;
zone->sectors = (smallest->sectors - zone->dev_start) * c;
sectors = (smallest->sectors - zone->dev_start) * c;
printk(KERN_INFO "raid0: zone->nb_dev: %d, sectors: %llu\n",
zone->nb_dev, (unsigned long long)zone->sectors);
zone->nb_dev, (unsigned long long)sectors);
curr_zone_end += zone->sectors;
curr_zone_end += sectors;
zone->zone_end = curr_zone_end;
printk(KERN_INFO "raid0: current zone start: %llu\n",
@ -310,16 +309,22 @@ static int raid0_stop(mddev_t *mddev)
return 0;
}
/* Find the zone which holds a particular offset */
/* Find the zone which holds a particular offset
* Update *sectorp to be an offset in that zone
*/
static struct strip_zone *find_zone(struct raid0_private_data *conf,
sector_t sector)
sector_t *sectorp)
{
int i;
struct strip_zone *z = conf->strip_zone;
sector_t sector = *sectorp;
for (i = 0; i < conf->nr_strip_zones; i++)
if (sector < z[i].zone_end)
if (sector < z[i].zone_end) {
if (i)
*sectorp = sector - z[i-1].zone_end;
return z + i;
}
BUG();
}
@ -331,7 +336,7 @@ static int raid0_make_request (struct request_queue *q, struct bio *bio)
struct strip_zone *zone;
mdk_rdev_t *tmp_dev;
sector_t chunk;
sector_t sector, rsect;
sector_t sector, rsect, sector_offset;
const int rw = bio_data_dir(bio);
int cpu;
@ -368,11 +373,11 @@ static int raid0_make_request (struct request_queue *q, struct bio *bio)
bio_pair_release(bp);
return 0;
}
zone = find_zone(conf, sector);
sector_offset = sector;
zone = find_zone(conf, &sector_offset);
sect_in_chunk = bio->bi_sector & (chunk_sects - 1);
{
sector_t x = (zone->sectors + sector - zone->zone_end)
>> chunksect_bits;
sector_t x = sector_offset >> chunksect_bits;
sector_div(x, zone->nb_dev);
chunk = x;

1
drivers/md/raid0.h
View File

@ -5,7 +5,6 @@ struct strip_zone
{
sector_t zone_end; /* Start of the next zone (in sectors) */
sector_t dev_start; /* Zone offset in real dev (in sectors) */
sector_t sectors; /* Zone size in sectors */
int nb_dev; /* # of devices attached to the zone */
mdk_rdev_t **dev; /* Devices attached to the zone */
};