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Optimize the use of splay in gbincore(). During a "make buildworld" the

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desired buffer is found at one of the roots more than 60% of the time.
Thus, checking both roots before performing either splay eliminates
unnecessary splays on the first tree splayed.

Approved by:	re (jhb)
This commit is contained in:
Alan Cox 2003-05-13 04:36:02 +00:00
parent 4a49423d71
commit 099e981aa1
1 changed files with 22 additions and 7 deletions
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29
sys/kern/vfs_subr.c
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@ -1565,6 +1565,11 @@ buf_vlist_add(struct buf *bp, struct vnode *vp, b_xflags_t xflags)
* *
* This code isn't quite efficient as it could be because we are maintaining * This code isn't quite efficient as it could be because we are maintaining
* two sorted lists and do not know which list the block resides in. * two sorted lists and do not know which list the block resides in.
*
* During a "make buildworld" the desired buffer is found at one of
* the roots more than 60% of the time. Thus, checking both roots
* before performing either splay eliminates unnecessary splays on the
* first tree splayed.
*/ */
struct buf * struct buf *
gbincore(struct vnode *vp, daddr_t lblkno) gbincore(struct vnode *vp, daddr_t lblkno)
@ -1574,13 +1579,23 @@ gbincore(struct vnode *vp, daddr_t lblkno)
GIANT_REQUIRED; GIANT_REQUIRED;
ASSERT_VI_LOCKED(vp, "gbincore"); ASSERT_VI_LOCKED(vp, "gbincore");
bp = vp->v_cleanblkroot = buf_splay(lblkno, 0, vp->v_cleanblkroot); if ((bp = vp->v_cleanblkroot) != NULL &&
if (bp && bp->b_lblkno == lblkno && !(bp->b_xflags & BX_BKGRDMARKER)) bp->b_lblkno == lblkno && !(bp->b_xflags & BX_BKGRDMARKER))
return(bp); return (bp);
bp = vp->v_dirtyblkroot = buf_splay(lblkno, 0, vp->v_dirtyblkroot); if ((bp = vp->v_dirtyblkroot) != NULL &&
if (bp && bp->b_lblkno == lblkno && !(bp->b_xflags & BX_BKGRDMARKER)) bp->b_lblkno == lblkno && !(bp->b_xflags & BX_BKGRDMARKER))
return(bp); return (bp);
return(NULL); if ((bp = vp->v_cleanblkroot) != NULL) {
vp->v_cleanblkroot = bp = buf_splay(lblkno, 0, bp);
if (bp->b_lblkno == lblkno && !(bp->b_xflags & BX_BKGRDMARKER))
return (bp);
}
if ((bp = vp->v_dirtyblkroot) != NULL) {
vp->v_dirtyblkroot = bp = buf_splay(lblkno, 0, bp);
if (bp->b_lblkno == lblkno && !(bp->b_xflags & BX_BKGRDMARKER))
return (bp);
}
return (NULL);
} }
/* /*