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xfs: speed up free inode search
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Don't search too far - abort if it is outside a certain radius and simply do
a linear search for the first free inode.  In AGs with a million inodes this
can speed up allocation speed by 3-4x.

[hch: ported to the new xfs_ialloc.c world order]

Signed-off-by: Dave Chinner <dgc@sgi.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alex Elder <aelder@sgi.com>
Signed-off-by: Felix Blyakher <felixb@sgi.com>
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Dave Chinner authored and Felix Blyakher committed Sep 1, 2009
1 parent 2187550 commit bd16956
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Showing 2 changed files with 115 additions and 27 deletions.
9 changes: 9 additions & 0 deletions fs/xfs/xfs_ag.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -198,6 +198,15 @@ typedef struct xfs_perag
xfs_agino_t pagi_count; /* number of allocated inodes */
int pagb_count; /* pagb slots in use */
xfs_perag_busy_t *pagb_list; /* unstable blocks */

/*
* Inode allocation search lookup optimisation.
* If the pagino matches, the search for new inodes
* doesn't need to search the near ones again straight away
*/
xfs_agino_t pagl_pagino;
xfs_agino_t pagl_leftrec;
xfs_agino_t pagl_rightrec;
#ifdef __KERNEL__
spinlock_t pagb_lock; /* lock for pagb_list */

Expand Down
133 changes: 106 additions & 27 deletions fs/xfs/xfs_ialloc.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -587,6 +587,30 @@ xfs_ialloc_next_rec(
return 0;
}

STATIC int
xfs_ialloc_get_rec(
struct xfs_btree_cur *cur,
xfs_agino_t agino,
xfs_inobt_rec_incore_t *rec,
int *done,
int left)
{
int error;
int i;

error = xfs_inobt_lookup(cur, agino, XFS_LOOKUP_EQ, &i);
if (error)
return error;
*done = !i;
if (i) {
error = xfs_inobt_get_rec(cur, rec, &i);
if (error)
return error;
XFS_WANT_CORRUPTED_RETURN(i == 1);
}

return 0;
}

/*
* Visible inode allocation functions.
Expand Down Expand Up @@ -766,6 +790,8 @@ xfs_dialloc(
*/
agno = tagno;
*IO_agbp = NULL;

restart_pagno:
cur = xfs_inobt_init_cursor(mp, tp, agbp, be32_to_cpu(agi->agi_seqno));
/*
* If pagino is 0 (this is the root inode allocation) use newino.
Expand All @@ -782,8 +808,10 @@ xfs_dialloc(
* If in the same AG as the parent, try to get near the parent.
*/
if (pagno == agno) {
xfs_perag_t *pag = &mp->m_perag[agno];
int doneleft; /* done, to the left */
int doneright; /* done, to the right */
int searchdistance = 10;

error = xfs_inobt_lookup(cur, pagino, XFS_LOOKUP_LE, &i);
if (error)
Expand Down Expand Up @@ -813,22 +841,51 @@ xfs_dialloc(
if (error)
goto error0;

/* search left with tcur, back up 1 record */
error = xfs_ialloc_next_rec(tcur, &trec, &doneleft, 1);
if (error)
goto error1;
/*
* Skip to last blocks looked up if same parent inode.
*/
if (pagino != NULLAGINO &&
pag->pagl_pagino == pagino &&
pag->pagl_leftrec != NULLAGINO &&
pag->pagl_rightrec != NULLAGINO) {
error = xfs_ialloc_get_rec(tcur, pag->pagl_leftrec,
&trec, &doneleft, 1);
if (error)
goto error1;

/* search right with cur, go forward 1 record. */
error = xfs_ialloc_next_rec(cur, &rec, &doneright, 0);
if (error)
goto error1;
error = xfs_ialloc_get_rec(cur, pag->pagl_rightrec,
&rec, &doneright, 0);
if (error)
goto error1;
} else {
/* search left with tcur, back up 1 record */
error = xfs_ialloc_next_rec(tcur, &trec, &doneleft, 1);
if (error)
goto error1;

/* search right with cur, go forward 1 record. */
error = xfs_ialloc_next_rec(cur, &rec, &doneright, 0);
if (error)
goto error1;
}

/*
* Loop until we find an inode chunk with a free inode.
*/
while (!doneleft || !doneright) {
int useleft; /* using left inode chunk this time */

if (!--searchdistance) {
/*
* Not in range - save last search
* location and allocate a new inode
*/
pag->pagl_leftrec = trec.ir_startino;
pag->pagl_rightrec = rec.ir_startino;
pag->pagl_pagino = pagino;
goto newino;
}

/* figure out the closer block if both are valid. */
if (!doneleft && !doneright) {
useleft = pagino -
Expand All @@ -843,12 +900,20 @@ xfs_dialloc(
rec = trec;
xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
cur = tcur;

pag->pagl_leftrec = trec.ir_startino;
pag->pagl_rightrec = rec.ir_startino;
pag->pagl_pagino = pagino;
goto alloc_inode;
}

/* free inodes to the right? */
if (!useleft && rec.ir_freecount) {
xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);

pag->pagl_leftrec = trec.ir_startino;
pag->pagl_rightrec = rec.ir_startino;
pag->pagl_pagino = pagino;
goto alloc_inode;
}

Expand All @@ -863,14 +928,28 @@ xfs_dialloc(
if (error)
goto error1;
}
ASSERT(!doneleft || !doneright);

/*
* We've reached the end of the btree. because
* we are only searching a small chunk of the
* btree each search, there is obviously free
* inodes closer to the parent inode than we
* are now. restart the search again.
*/
pag->pagl_pagino = NULLAGINO;
pag->pagl_leftrec = NULLAGINO;
pag->pagl_rightrec = NULLAGINO;
xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);
xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
goto restart_pagno;
}

/*
* In a different AG from the parent.
* See if the most recently allocated block has any free.
*/
else if (be32_to_cpu(agi->agi_newino) != NULLAGINO) {
newino:
if (be32_to_cpu(agi->agi_newino) != NULLAGINO) {
error = xfs_inobt_lookup(cur, be32_to_cpu(agi->agi_newino),
XFS_LOOKUP_EQ, &i);
if (error)
Expand All @@ -889,27 +968,27 @@ xfs_dialloc(
goto alloc_inode;
}
}
}

/*
* None left in the last group, search the whole AG
*/
error = xfs_inobt_lookup(cur, 0, XFS_LOOKUP_GE, &i);
/*
* None left in the last group, search the whole AG
*/
error = xfs_inobt_lookup(cur, 0, XFS_LOOKUP_GE, &i);
if (error)
goto error0;
XFS_WANT_CORRUPTED_GOTO(i == 1, error0);

for (;;) {
error = xfs_inobt_get_rec(cur, &rec, &i);
if (error)
goto error0;
XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
if (rec.ir_freecount > 0)
break;
error = xfs_btree_increment(cur, 0, &i);
if (error)
goto error0;
XFS_WANT_CORRUPTED_GOTO(i == 1, error0);

for (;;) {
error = xfs_inobt_get_rec(cur, &rec, &i);
if (error)
goto error0;
XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
if (rec.ir_freecount > 0)
break;
error = xfs_btree_increment(cur, 0, &i);
if (error)
goto error0;
XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
}
}

alloc_inode:
Expand Down

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