PERFORCE change 212957 for review

[John Baldwin]

http://p4web.freebsd.org/@@212957?ac=10

Change 212957 by jhb at jhb_jhbbsd on 2012/06/16 16:13:23

	WILLNEED experimenting:
	- Add a variant of breada() that uses GB_LOCK_NOWAIT.
	
	NOREUSE changes:
	- Add counters to instrument what happens during DONTNEED requests.

Affected files ...

.. //depot/projects/fadvise/sys/kern/vfs_bio.c#7 edit
.. //depot/projects/fadvise/sys/sys/buf.h#4 edit
.. //depot/projects/fadvise/sys/ufs/ffs/ffs_vnops.c#10 edit

Differences ...

==== //depot/projects/fadvise/sys/kern/vfs_bio.c#7 (text+ko) ====

@@ -94,6 +94,8 @@
 
 static struct proc *bufdaemonproc;
 
+static void breada_flags(struct vnode * vp, daddr_t * rablkno, int * rabsize,
+		int cnt, struct ucred * cred, int gbflags);
 static int inmem(struct vnode *vp, daddr_t blkno);
 static void vm_hold_free_pages(struct buf *bp, int newbsize);
 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from,
@@ -788,8 +790,8 @@
  * the buffer is valid and we do not have to do anything.
  */
 void
-breada(struct vnode * vp, daddr_t * rablkno, int * rabsize,
-    int cnt, struct ucred * cred)
+breada_flags(struct vnode * vp, daddr_t * rablkno, int * rabsize,
+    int cnt, struct ucred * cred, int gbflags)
 {
 	struct buf *rabp;
 	int i;
@@ -797,7 +799,7 @@
 	for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
 		if (inmem(vp, *rablkno))
 			continue;
-		rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
+		rabp = getblk(vp, *rablkno, *rabsize, 0, 0, gbflags);
 
 		if ((rabp->b_flags & B_CACHE) == 0) {
 			if (!TD_IS_IDLETHREAD(curthread))
@@ -818,6 +820,22 @@
 	}
 }
 
+void
+breada(struct vnode * vp, daddr_t * rablkno, int * rabsize,
+    int cnt, struct ucred * cred)
+{
+
+	breada_flags(vp, rablkno, rabsize, cnt, cred, 0);
+}
+
+void
+breada_nowait(struct vnode * vp, daddr_t * rablkno, int * rabsize,
+    int cnt, struct ucred * cred)
+{
+
+	breada_flags(vp, rablkno, rabsize, cnt, cred, GB_LOCK_NOWAIT);
+}
+
 /*
  * Entry point for bread() and breadn() via #defines in sys/buf.h.
  *
@@ -1212,6 +1230,36 @@
 	return vm_page_count_severe();
 }
 
+static SYSCTL_NODE(_vfs, OID_AUTO, brelse, CTLFLAG_RD, NULL, "brelse stats");
+
+static int brelse_discard1;
+SYSCTL_INT(_vfs_brelse, OID_AUTO, discard1, CTLFLAG_RD, &brelse_discard1, 0,
+    "");
+static int brelse_rundown1;
+SYSCTL_INT(_vfs_brelse, OID_AUTO, rundown1, CTLFLAG_RD, &brelse_rundown1, 0,
+    "");
+static int brelse_rundown2;
+SYSCTL_INT(_vfs_brelse, OID_AUTO, rundown2, CTLFLAG_RD, &brelse_rundown2, 0,
+    "");
+static int brelse_rundown3;
+SYSCTL_INT(_vfs_brelse, OID_AUTO, rundown3, CTLFLAG_RD, &brelse_rundown3, 0,
+    "");
+static int brelse_inval;
+SYSCTL_INT(_vfs_brelse, OID_AUTO, inval, CTLFLAG_RD, &brelse_inval, 0,
+    "");
+static int brelse_discard_nocache;
+SYSCTL_INT(_vfs_brelse, OID_AUTO, discard_nocache, CTLFLAG_RD,
+    &brelse_discard_nocache, 0, "");
+static int brelse_discard_inval;
+SYSCTL_INT(_vfs_brelse, OID_AUTO, discard_inval, CTLFLAG_RD,
+    &brelse_discard_inval, 0, "");
+static int brelse_discard_error;
+SYSCTL_INT(_vfs_brelse, OID_AUTO, discard_error, CTLFLAG_RD,
+    &brelse_discard_error, 0, "");
+static int brelse_discard_badsize;
+SYSCTL_INT(_vfs_brelse, OID_AUTO, discard_badsize, CTLFLAG_RD,
+    &brelse_discard_badsize, 0, "");
+
 /*
  *	brelse:
  *
@@ -1248,6 +1296,15 @@
 		 * Either a failed I/O or we were asked to free or not
 		 * cache the buffer.
 		 */
+		brelse_discard1++;
+		if (bp->b_flags & B_NOCACHE)
+			brelse_discard_nocache++;
+		if (bp->b_flags & B_INVAL)
+			brelse_discard_inval++;
+		if (bp->b_ioflags & BIO_ERROR)
+			brelse_discard_error++;
+		if (bp->b_bufsize <= 0)
+			brelse_discard_badsize++;
 		bp->b_flags |= B_INVAL;
 		if (!LIST_EMPTY(&bp->b_dep))
 			buf_deallocate(bp);
@@ -1387,16 +1444,18 @@
 			foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
 		}
 		VM_OBJECT_UNLOCK(obj);
+		brelse_rundown1++;
 		if (bp->b_flags & (B_INVAL | B_RELBUF))
 			vfs_vmio_release(bp);
 
 	} else if (bp->b_flags & B_VMIO) {
-
+		brelse_rundown2++;
 		if (bp->b_flags & (B_INVAL | B_RELBUF)) {
 			vfs_vmio_release(bp);
 		}
 
 	} else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) {
+		brelse_rundown3++;
 		if (bp->b_bufsize != 0)
 			allocbuf(bp, 0);
 		if (bp->b_vp != NULL)
@@ -1434,6 +1493,8 @@
 	    (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0)
 		bp->b_flags |= B_INVAL;
 	if (bp->b_flags & B_INVAL) {
+		if (bp->b_bufsize != 0)
+			brelse_inval++;
 		if (bp->b_flags & B_DELWRI)
 			bundirty(bp);
 		if (bp->b_vp)

==== //depot/projects/fadvise/sys/sys/buf.h#4 (text+ko) ====

@@ -490,6 +490,7 @@
 int	breadn_flags(struct vnode *, daddr_t, int, daddr_t *, int *, int,
 	    struct ucred *, int, struct buf **);
 void	breada(struct vnode *, daddr_t *, int *, int, struct ucred *);
+void	breada_nowait(struct vnode *, daddr_t *, int *, int, struct ucred *);
 void	bdwrite(struct buf *);
 void	bawrite(struct buf *);
 void	bdirty(struct buf *);

==== //depot/projects/fadvise/sys/ufs/ffs/ffs_vnops.c#10 (text+ko) ====

@@ -530,7 +530,7 @@
 				xfersize = fs->fs_bsize - blkoffset;
 				if (resid < xfersize)
 					xfersize = resid;
-				breada(vp, &lbn, &xfersize, 1, NOCRED);
+				breada_nowait(vp, &lbn, &xfersize, 1, NOCRED);
 			}
 			resid -= xfersize;
 			start += xfersize;