Dynamic buffer cache. Initial diff from mickey@, okay art@ beck@ toby@

deraadt@ dlg@.

1 files changed, 4 insertions, 501 deletions

diff --git a/sys/kern/vfs_cluster.c b/sys/kern/vfs_cluster.c
index d104ec12934..7d31ed887a2 100644
--- a/sys/kern/vfs_cluster.c
+++ b/sys/kern/vfs_cluster.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vfs_cluster.c,v 1.36 2006/10/16 11:27:53 pedro Exp $	*/
+/*	$OpenBSD: vfs_cluster.c,v 1.37 2007/05/26 20:26:51 pedro Exp $	*/
 /*	$NetBSD: vfs_cluster.c,v 1.12 1996/04/22 01:39:05 christos Exp $	*/
 
 /*
@@ -43,409 +43,11 @@
 
 #include <uvm/uvm_extern.h>
 
-void cluster_callback(struct buf *);
-struct buf *cluster_newbuf(struct vnode *, struct buf *, long, daddr64_t,
-    daddr64_t, long, int);
-struct buf *cluster_rbuild(struct vnode *, u_quad_t, struct buf *, daddr64_t,
-    daddr64_t, long, int, long);
 void cluster_wbuild(struct vnode *, struct buf *, long, daddr64_t, int,
     daddr64_t);
 struct cluster_save *cluster_collectbufs(struct vnode *, struct cluster_info *,
     struct buf *);
 
-#ifdef DIAGNOSTIC
-/*
- * Set to 1 if reads of block zero should cause readahead to be done.
- * Set to 0 treats a read of block zero as a non-sequential read.
- *
- * Setting to one assumes that most reads of block zero of files are due to
- * sequential passes over the files (e.g. cat, sum) where additional blocks
- * will soon be needed.  Setting to zero assumes that the majority are
- * surgical strikes to get particular info (e.g. size, file) where readahead
- * blocks will not be used and, in fact, push out other potentially useful
- * blocks from the cache.  The former seems intuitive, but some quick tests
- * showed that the latter performed better from a system-wide point of view.
- */
-int	doclusterraz = 0;
-#define ISSEQREAD(ci, blk) \
-	(((blk) != 0 || doclusterraz) && \
-	 ((blk) == (ci)->ci_lastr + 1 || (blk) == (ci)->ci_lastr))
-#else
-#define ISSEQREAD(ci, blk) \
-	((blk) != 0 && ((blk) == (ci)->ci_lastr + 1 || (blk) == (ci)->ci_lastr))
-#endif
-
-/*
- * This replaces bread.  If this is a bread at the beginning of a file and
- * lastr is 0, we assume this is the first read and we'll read up to two
- * blocks if they are sequential.  After that, we'll do regular read ahead
- * in clustered chunks.
- *
- * There are 4 or 5 cases depending on how you count:
- *	Desired block is in the cache:
- *	    1 Not sequential access (0 I/Os).
- *	    2 Access is sequential, do read-ahead (1 ASYNC).
- *	Desired block is not in cache:
- *	    3 Not sequential access (1 SYNC).
- *	    4 Sequential access, next block is contiguous (2 SYNC).
- *	    5 Sequential access, next block is not contiguous (1 SYNC, 1 ASYNC)
- *
- * There are potentially two buffers that require I/O.
- * 	bp is the block requested.
- *	rbp is the read-ahead block.
- *	If either is NULL, then you don't have to do the I/O.
- */
-int
-cluster_read(struct vnode *vp, struct cluster_info *ci, u_quad_t filesize,
-    daddr64_t lblkno, long size, struct ucred *cred, struct buf **bpp)
-{
-	struct buf *bp, *rbp;
-	daddr64_t blkno, ioblkno;
-	long flags;
-	int error, num_ra, alreadyincore;
-
-#ifdef DIAGNOSTIC
-	if (size == 0)
-		panic("cluster_read: size = 0");
-#endif
-
-	error = 0;
-	flags = B_READ;
-	*bpp = bp = getblk(vp, lblkno, size, 0, 0);
-	if (bp->b_flags & B_CACHE) {
-		/*
-		 * Desired block is in cache; do any readahead ASYNC.
-		 * Case 1, 2.
-		 */
-		flags |= B_ASYNC;
-		ioblkno = lblkno + (ci->ci_ralen ? ci->ci_ralen : 1);
-		alreadyincore = incore(vp, ioblkno) != NULL;
-		bp = NULL;
-	} else {
-		/* Block wasn't in cache, case 3, 4, 5. */
-		bp->b_flags |= B_READ;
-		ioblkno = lblkno;
-		alreadyincore = 0;
-		curproc->p_stats->p_ru.ru_inblock++;		/* XXX */
-	}
-	/*
-	 * XXX
-	 * Replace 1 with a window size based on some permutation of
-	 * maxcontig and rot_delay.  This will let you figure out how
-	 * many blocks you should read-ahead (case 2, 4, 5).
-	 *
-	 * If the access isn't sequential, reset the window to 1.
-	 * Note that a read to the same block is considered sequential.
-	 * This catches the case where the file is being read sequentially,
-	 * but at smaller than the filesystem block size.
-	 */
-	rbp = NULL;
-	if (!ISSEQREAD(ci, lblkno)) {
-		ci->ci_ralen = 0;
-		ci->ci_maxra = lblkno;
-	} else if ((u_quad_t)(ioblkno + 1) * (u_quad_t)size <= filesize &&
-		   !alreadyincore &&
-		   !(error = VOP_BMAP(vp, ioblkno, NULL, &blkno, &num_ra)) &&
-		   blkno != -1) {
-		/*
-		 * Reading sequentially, and the next block is not in the
-		 * cache.  We are going to try reading ahead.
-		 */
-		if (num_ra) {
-			/*
-			 * If our desired readahead block had been read
-			 * in a previous readahead but is no longer in
-			 * core, then we may be reading ahead too far
-			 * or are not using our readahead very rapidly.
-			 * In this case we scale back the window.
-			 */
-			if (!alreadyincore && ioblkno <= ci->ci_maxra)
-				ci->ci_ralen = max(ci->ci_ralen >> 1, 1);
-			/*
-			 * There are more sequential blocks than our current
-			 * window allows, scale up.  Ideally we want to get
-			 * in sync with the filesystem maxcontig value.
-			 */
-			else if (num_ra > ci->ci_ralen && lblkno != ci->ci_lastr)
-				ci->ci_ralen = ci->ci_ralen ?
-					min(num_ra, ci->ci_ralen << 1) : 1;
-
-			if (num_ra > ci->ci_ralen)
-				num_ra = ci->ci_ralen;
-		}
-
-		if (num_ra)				/* case 2, 4 */
-			rbp = cluster_rbuild(vp, filesize,
-			    bp, ioblkno, blkno, size, num_ra, flags);
-		else if (ioblkno == lblkno) {
-			bp->b_blkno = blkno;
-			/* Case 5: check how many blocks to read ahead */
-			++ioblkno;
-			if ((u_quad_t)(ioblkno + 1) * (u_quad_t)size >
-			    filesize ||
-			    incore(vp, ioblkno) || (error = VOP_BMAP(vp,
-			    ioblkno, NULL, &blkno, &num_ra)) || blkno == -1)
-				goto skip_readahead;
-			/*
-			 * Adjust readahead as above.
-			 * Don't check alreadyincore, we know it is 0 from
-			 * the previous conditional.
-			 */
-			if (num_ra) {
-				if (ioblkno <= ci->ci_maxra)
-					ci->ci_ralen = max(ci->ci_ralen >> 1, 1);
-				else if (num_ra > ci->ci_ralen &&
-					 lblkno != ci->ci_lastr)
-					ci->ci_ralen = ci->ci_ralen ?
-						min(num_ra,ci->ci_ralen<<1) : 1;
-				if (num_ra > ci->ci_ralen)
-					num_ra = ci->ci_ralen;
-			}
-			flags |= B_ASYNC;
-			if (num_ra)
-				rbp = cluster_rbuild(vp, filesize,
-				    NULL, ioblkno, blkno, size, num_ra, flags);
-			else {
-				rbp = getblk(vp, ioblkno, size, 0, 0);
-				rbp->b_flags |= flags;
-				rbp->b_blkno = blkno;
-			}
-		} else {
-			/* case 2; read ahead single block */
-			rbp = getblk(vp, ioblkno, size, 0, 0);
-			rbp->b_flags |= flags;
-			rbp->b_blkno = blkno;
-		}
-
-		if (rbp == bp)			/* case 4 */
-			rbp = NULL;
-		else if (rbp)			/* case 2, 5 */
-			curproc->p_stats->p_ru.ru_inblock++;	/* XXX */
-	}
-
-	/* XXX Kirk, do we need to make sure the bp has creds? */
-skip_readahead:
-	if (bp) {
-		if (bp->b_flags & (B_DONE | B_DELWRI))
-			panic("cluster_read: DONE bp");
-		else
-			error = VOP_STRATEGY(bp);
-	}
-
-	if (rbp) {
-		if (error || rbp->b_flags & (B_DONE | B_DELWRI)) {
-			rbp->b_flags &= ~(B_ASYNC | B_READ);
-			brelse(rbp);
-		} else
-			(void) VOP_STRATEGY(rbp);
-	}
-
-	/*
-	 * Recalculate our maximum readahead
-	 */
-	if (rbp == NULL)
-		rbp = bp;
-	if (rbp)
-		ci->ci_maxra = rbp->b_lblkno + (rbp->b_bcount / size) - 1;
-
-	if (bp)
-		return(biowait(bp));
-	return(error);
-}
-
-/*
- * If blocks are contiguous on disk, use this to provide clustered
- * read ahead.  We will read as many blocks as possible sequentially
- * and then parcel them up into logical blocks in the buffer hash table.
- */
-struct buf *
-cluster_rbuild(struct vnode *vp, u_quad_t filesize, struct buf *bp,
-    daddr64_t lbn, daddr64_t blkno, long size, int run, long flags)
-{
-	struct cluster_save *b_save;
-	struct buf *tbp;
-	daddr64_t bn;
-	int i, inc;
-
-#ifdef DIAGNOSTIC
-	if (size != vp->v_mount->mnt_stat.f_iosize)
-		panic("cluster_rbuild: size %ld != filesize %ld",
-			size, vp->v_mount->mnt_stat.f_iosize);
-#endif
-	if ((u_quad_t)size * (u_quad_t)(lbn + run + 1) > filesize)
-		--run;
-	if (run == 0) {
-		if (!bp) {
-			bp = getblk(vp, lbn, size, 0, 0);
-			bp->b_blkno = blkno;
-			bp->b_flags |= flags;
-		}
-		return(bp);
-	}
-
-	bp = cluster_newbuf(vp, bp, flags, blkno, lbn, size, run + 1);
-	if (bp->b_flags & (B_DONE | B_DELWRI))
-		return (bp);
-
-	b_save = malloc(sizeof(struct buf *) * run +
-	    sizeof(struct cluster_save), M_VCLUSTER, M_WAITOK);
-	b_save->bs_bufsize = b_save->bs_bcount = size;
-	b_save->bs_nchildren = 0;
-	b_save->bs_children = (struct buf **)(b_save + 1);
-	b_save->bs_saveaddr = bp->b_saveaddr;
-	bp->b_saveaddr = b_save;
-
-	inc = btodb(size);
-	for (bn = blkno + inc, i = 1; i <= run; ++i, bn += inc) {
-		/*
-		 * A component of the cluster is already in core,
-		 * terminate the cluster early.
-		 */
-		if (incore(vp, lbn + i))
-			break;
-		tbp = getblk(vp, lbn + i, 0, 0, 0);
-
-		/*
-		 * getblk may return some memory in the buffer if there were
-		 * no empty buffers to shed it to.  If there is currently
-		 * memory in the buffer, we move it down size bytes to make
-		 * room for the valid pages that cluster_callback will insert.
-		 * We do this now so we don't have to do it at interrupt time
-		 * in the callback routine.
-		 */
-		if (tbp->b_bufsize != 0) {
-			caddr_t bdata = tbp->b_data;
-
-			/*
-			 * No room in the buffer to add another page,
-			 * terminate the cluster early.
-			 */
-			if (tbp->b_bufsize + size > MAXBSIZE) {
-#ifdef DIAGNOSTIC
-				if (tbp->b_bufsize > MAXBSIZE)
-					panic("cluster_rbuild: too much memory");
-#endif
-				/* This buffer is *not* valid.  */
-				tbp->b_flags |= B_INVAL;
-				brelse(tbp);
-				break;
-			}
-			pagemove(bdata, bdata + tbp->b_bufsize, size);
-		}
-		tbp->b_blkno = bn;
-		tbp->b_flags &= ~(B_DONE | B_ERROR);
-		tbp->b_flags |= flags | B_READ | B_ASYNC;
-		b_save->bs_children[b_save->bs_nchildren++] = tbp;
-	}
-	/*
-	 * The cluster may have been terminated early, adjust the cluster
-	 * buffer size accordingly.  If no cluster could be formed,
-	 * deallocate the cluster save info.
-	 */
-	if (i <= run) {
-		if (i == 1) {
-			bp->b_saveaddr = b_save->bs_saveaddr;
-			bp->b_flags &= ~B_CALL;
-			bp->b_iodone = NULL;
-			free(b_save, M_VCLUSTER);
-		}
-		allocbuf(bp, size * i);
-	}
-	return(bp);
-}
-
-/*
- * Either get a new buffer or grow the existing one.
- */
-struct buf *
-cluster_newbuf(struct vnode *vp, struct buf *bp, long flags, daddr64_t blkno,
-    daddr64_t lblkno, long size, int run)
-{
-	if (!bp) {
-		bp = getblk(vp, lblkno, size, 0, 0);
-		if (bp->b_flags & (B_DONE | B_DELWRI)) {
-			bp->b_blkno = blkno;
-			return(bp);
-		}
-	}
-	allocbuf(bp, run * size);
-	bp->b_blkno = blkno;
-	bp->b_iodone = cluster_callback;
-	bp->b_flags |= flags | B_CALL;
-	return(bp);
-}
-
-/*
- * Cleanup after a clustered read or write.
- * This is complicated by the fact that any of the buffers might have
- * extra memory (if there were no empty buffer headers at allocbuf time)
- * that we will need to shift around.
- */
-void
-cluster_callback(struct buf *bp)
-{
-	struct cluster_save *b_save;
-	struct buf **bpp, *tbp;
-	long bsize;
-	caddr_t cp;
-	int error = 0;
-
-	splassert(IPL_BIO);
-
-	/*
-	 * Must propagate errors to all the components.
-	 */
-	if (bp->b_flags & B_ERROR)
-		error = bp->b_error;
-
-	b_save = (struct cluster_save *)(bp->b_saveaddr);
-	bp->b_saveaddr = b_save->bs_saveaddr;
-
-	bsize = b_save->bs_bufsize;
-	cp = (char *)bp->b_data + bsize;
-	/*
-	 * Move memory from the large cluster buffer into the component
-	 * buffers and mark IO as done on these.
-	 */
-	for (bpp = b_save->bs_children; b_save->bs_nchildren--; ++bpp) {
-		tbp = *bpp;
-		pagemove(cp, tbp->b_data, bsize);
-		tbp->b_bufsize += bsize;
-		tbp->b_bcount = bsize;
-		if (error) {
-			tbp->b_flags |= B_ERROR;
-			tbp->b_error = error;
-		}
-		biodone(tbp);
-		bp->b_bufsize -= bsize;
-		cp += bsize;
-	}
-	/*
-	 * If there was excess memory in the cluster buffer,
-	 * slide it up adjacent to the remaining valid data.
-	 */
-	if (bp->b_bufsize != bsize) {
-		if (bp->b_bufsize < bsize)
-			panic("cluster_callback: too little memory");
-		if (bp->b_bufsize < cp - (char *)bp->b_data)
-			pagemove(cp, (char *)bp->b_data + bsize,
-			    bp->b_bufsize - bsize);
-		else
-			pagemove((char *)bp->b_data + bp->b_bufsize,
-			    (char *)bp->b_data + bsize,
-			    cp - ((char *)bp->b_data + bsize));
-	}
-	bp->b_bcount = bsize;
-	bp->b_iodone = NULL;
-	free(b_save, M_VCLUSTER);
-	if (bp->b_flags & B_ASYNC)
-		brelse(bp);
-	else {
-		bp->b_flags &= ~B_WANTED;
-		wakeup(bp);
-	}
-}
-
 /*
  * Do clustered write for FFS.
  *
@@ -561,7 +163,6 @@ cluster_write(struct buf *bp, struct cluster_info *ci, u_quad_t filesize)
 }
 
 /*
- * This is an awful lot like cluster_rbuild...wish they could be combined.
  * The last lbn argument is the current block on which I/O is being
  * performed.  Check to see that it doesn't fall in the middle of
  * the current block (if last_bp == NULL).
@@ -570,10 +171,7 @@ void
 cluster_wbuild(struct vnode *vp, struct buf *last_bp, long size,
     daddr64_t start_lbn, int len, daddr64_t lbn)
 {
-	struct cluster_save *b_save;
-	struct buf *bp, *tbp;
-	caddr_t	cp;
-	int i, s;
+	struct buf *bp;
 
 #ifdef DIAGNOSTIC
 	if (size != vp->v_mount->mnt_stat.f_iosize)
@@ -613,105 +211,10 @@ redo:
 		goto redo;
 	}
 
-	/*
-	 * Extra memory in the buffer, punt on this buffer.
-	 * XXX we could handle this in most cases, but we would have to
-	 * push the extra memory down to after our max possible cluster
-	 * size and then potentially pull it back up if the cluster was
-	 * terminated prematurely--too much hassle.
-	 */
-	if (bp->b_bcount != bp->b_bufsize) {
-		++start_lbn;
-		--len;
-		bawrite(bp);
-		goto redo;
-	}
-
+	++start_lbn;
 	--len;
-	b_save = malloc(sizeof(struct buf *) * len +
-	    sizeof(struct cluster_save), M_VCLUSTER, M_WAITOK);
-	b_save->bs_bcount = bp->b_bcount;
-	b_save->bs_bufsize = bp->b_bufsize;
-	b_save->bs_nchildren = 0;
-	b_save->bs_children = (struct buf **)(b_save + 1);
-	b_save->bs_saveaddr = bp->b_saveaddr;
-	bp->b_saveaddr = b_save;
-
-	bp->b_flags |= B_CALL;
-	bp->b_iodone = cluster_callback;
-	cp = (char *)bp->b_data + size;
-	for (++start_lbn, i = 0; i < len; ++i, ++start_lbn) {
-		/*
-		 * Block is not in core or the non-sequential block
-		 * ending our cluster was part of the cluster (in which
-		 * case we don't want to write it twice).
-		 */
-		if (!incore(vp, start_lbn) ||
-		    (last_bp == NULL && start_lbn == lbn))
-			break;
-
-		/*
-		 * Get the desired block buffer (unless it is the final
-		 * sequential block whose buffer was passed in explicitly
-		 * as last_bp).
-		 */
-		if (last_bp == NULL || start_lbn != lbn) {
-			tbp = getblk(vp, start_lbn, size, 0, 0);
-			if (!(tbp->b_flags & B_DELWRI)) {
-				brelse(tbp);
-				break;
-			}
-		} else
-			tbp = last_bp;
-
-		++b_save->bs_nchildren;
-
-		if (tbp->b_blkno != (bp->b_blkno + btodb(bp->b_bufsize))) {
-			printf("Clustered Block: %d addr %x bufsize: %ld\n",
-			    bp->b_lblkno, bp->b_blkno, bp->b_bufsize);
-			printf("Child Block: %d addr: %x\n", tbp->b_lblkno,
-			    tbp->b_blkno);
-			panic("Clustered write to wrong blocks");
-		}
-
-		/*
-		 * We might as well AGE the buffer here; it's either empty, or
-		 * contains data that we couldn't get rid of (but wanted to).
-		 */
-		tbp->b_flags &= ~(B_READ | B_DONE | B_ERROR);
-		tbp->b_flags |= (B_ASYNC | B_AGE);
-		s = splbio();
-		buf_undirty(tbp);
-		++tbp->b_vp->v_numoutput;
-		splx(s);
-
-		if (LIST_FIRST(&tbp->b_dep) != NULL)
-			buf_start(tbp);
-
-		/* Move memory from children to parent */
-		pagemove(tbp->b_data, cp, size);
-		bp->b_bcount += size;
-		bp->b_bufsize += size;
-
-		tbp->b_bufsize -= size;
-		b_save->bs_children[i] = tbp;
-
-		cp += size;
-	}
-
-	if (i == 0) {
-		/* None to cluster */
-		bp->b_saveaddr = b_save->bs_saveaddr;
-		bp->b_flags &= ~B_CALL;
-		bp->b_iodone = NULL;
-		free(b_save, M_VCLUSTER);
-	}
 	bawrite(bp);
-	if (i < len) {
-		len -= i + 1;
-		start_lbn += 1;
-		goto redo;
-	}
+	goto redo;
 }
 
 /*