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[XFS] Fix inode reclaim scalability regression. When a filesystem has

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millions of inodes cached and has sparse cluster population, removing
inodes from the cluster hash consumes excessive amounts of CPU time.
Reduce the CPU cost by making removal O(1) via use of a double linked list
for the hash chains.

SGI-PV: 951551
SGI-Modid: xfs-linux-melb:xfs-kern:25683a

Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Nathan Scott <nathans@sgi.com>
This commit is contained in:
David Chinner 2006-04-11 15:11:12 +10:00 committed by Nathan Scott
parent 8272145c05
commit 1fc5d959d8
2 changed files with 13 additions and 17 deletions
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29
fs/xfs/xfs_iget.c
View file

@ -421,7 +421,10 @@ xfs_iget_core(
ip->i_chash = chlnew;
chlnew->chl_ip = ip;
chlnew->chl_blkno = ip->i_blkno;
if (ch->ch_list)
ch->ch_list->chl_prev = chlnew;
chlnew->chl_next = ch->ch_list;
chlnew->chl_prev = NULL;
ch->ch_list = chlnew;
chlnew = NULL;
}
@ -723,23 +726,15 @@ xfs_iextract(
ASSERT(ip->i_cnext == ip && ip->i_cprev == ip);
ASSERT(ip->i_chash != NULL);
chm=NULL;
for (chl = ch->ch_list; chl != NULL; chl = chl->chl_next) {
if (chl->chl_blkno == ip->i_blkno) {
if (chm == NULL) {
/* first item on the list */
ch->ch_list = chl->chl_next;
} else {
chm->chl_next = chl->chl_next;
}
kmem_zone_free(xfs_chashlist_zone, chl);
break;
} else {
ASSERT(chl->chl_ip != ip);
chm = chl;
}
}
ASSERT_ALWAYS(chl != NULL);
} else {
chl = ip->i_chash;
if (chl->chl_prev)
chl->chl_prev->chl_next = chl->chl_next;
else
ch->ch_list = chl->chl_next;
if (chl->chl_next)
chl->chl_next->chl_prev = chl->chl_prev;
kmem_zone_free(xfs_chashlist_zone, chl);
} else {
/* delete one inode from a non-empty list */
iq = ip->i_cnext;
iq->i_cprev = ip->i_cprev;

1
fs/xfs/xfs_inode.h
View file

@ -189,6 +189,7 @@ typedef struct xfs_ihash {
*/
typedef struct xfs_chashlist {
struct xfs_chashlist *chl_next;
struct xfs_chashlist *chl_prev;
struct xfs_inode *chl_ip;
xfs_daddr_t chl_blkno; /* starting block number of
* the cluster */