Date: Fri, 17 Dec 1999 11:18:18 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Vallo Kallaste <vallo@matti.ee> Cc: "Rodney W. Grimes" <freebsd@gndrsh.dnsmgr.net>, freebsd-current@FreeBSD.ORG Subject: Re: Weird story with dump | restore Message-ID: <199912171918.LAA64133@apollo.backplane.com> References: <19991217123742.A70473@myhakas.matti.ee> <199912171648.IAA29595@gndrsh.dnsmgr.net> <19991217210227.A945@myhakas.matti.ee>
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:The source filesystems were both standard with bsize 8192 and fsize
:1024. Target filesystems were nonstandard.
:
:I umounted the source filesystem, in the exact case /usr (/dev/ad0s1e),
:then mounted target filesystem to /mnt, cd to /mnt and
:
:dump -0a -f - /dev/ad0s1e | restore rf -
:--
:
:Vallo Kallaste
:vallo@matti.ee
Try this patch to -current, it should solve the problem. I've been
meaning to fixup the buf_daemon for a while. This solves the
buf_daemon problem. We still will not be entirely optimal due to kvm
reshuffling but that's a different problem.
-Matt
Index: vfs_bio.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/vfs_bio.c,v
retrieving revision 1.237
diff -u -r1.237 vfs_bio.c
--- vfs_bio.c 1999/12/01 02:09:29 1.237
+++ vfs_bio.c 1999/12/17 18:44:40
@@ -88,7 +88,7 @@
bufmallocspace, maxbufmallocspace, hibufspace;
static int maxbdrun;
static int needsbuffer;
-static int numdirtybuffers, lodirtybuffers, hidirtybuffers;
+static int numdirtybuffers, hidirtybuffers;
static int numfreebuffers, lofreebuffers, hifreebuffers;
static int getnewbufcalls;
static int getnewbufrestarts;
@@ -96,8 +96,6 @@
SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD,
&numdirtybuffers, 0, "");
-SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW,
- &lodirtybuffers, 0, "");
SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW,
&hidirtybuffers, 0, "");
SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD,
@@ -275,6 +273,16 @@
}
}
+/*
+ * bd_speedup - speedup the buffer cache flushing code
+ */
+
+static __inline__
+void
+bd_speedup(void)
+{
+ bd_wakeup(1);
+}
/*
* Initialize buffer headers and related structures.
@@ -353,7 +361,6 @@
* Reduce the chance of a deadlock occuring by limiting the number
* of delayed-write dirty buffers we allow to stack up.
*/
- lodirtybuffers = nbuf / 7 + 10;
hidirtybuffers = nbuf / 4 + 20;
numdirtybuffers = 0;
/*
@@ -365,14 +372,9 @@
* the buffer cache.
*/
while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
- lodirtybuffers >>= 1;
hidirtybuffers >>= 1;
buf_maxio >>= 1;
}
- if (lodirtybuffers < 2) {
- lodirtybuffers = 2;
- hidirtybuffers = 4;
- }
/*
* Temporary, BKVASIZE may be manipulated soon, make sure we don't
@@ -799,9 +801,9 @@
void
bwillwrite(void)
{
- int twenty = (hidirtybuffers - lodirtybuffers) / 5;
+ int slop = hidirtybuffers / 10;
- if (numdirtybuffers > hidirtybuffers + twenty) {
+ if (numdirtybuffers > hidirtybuffers + slop) {
int s;
s = splbio();
@@ -1571,9 +1573,8 @@
flags = VFS_BIO_NEED_ANY;
}
- /* XXX */
+ bd_speedup(); /* heeeelp */
- (void) speedup_syncer();
needsbuffer |= flags;
while (needsbuffer & flags) {
if (tsleep(&needsbuffer, (PRIBIO + 4) | slpflag,
@@ -1652,6 +1653,7 @@
static struct proc *bufdaemonproc;
static int bd_interval;
static int bd_flushto;
+static int bd_flushinc;
static struct kproc_desc buf_kp = {
"bufdaemon",
@@ -1672,6 +1674,7 @@
bd_interval = 5 * hz; /* dynamically adjusted */
bd_flushto = hidirtybuffers; /* dynamically adjusted */
+ bd_flushinc = 1;
while (TRUE) {
bd_request = 0;
@@ -1694,44 +1697,38 @@
}
}
- /*
- * If nobody is requesting anything we sleep
- */
- if (bd_request == 0)
- tsleep(&bd_request, PVM, "psleep", bd_interval);
+ if (bd_request ||
+ tsleep(&bd_request, PVM, "psleep", bd_interval) == 0) {
+ /*
+ * Another request is pending or we were woken up
+ * without timing out. Flush more.
+ */
+ --bd_flushto;
+ if (bd_flushto >= numdirtybuffers - 5) {
+ bd_flushto = numdirtybuffers - 10;
+ bd_flushinc = 1;
+ }
+ if (bd_flushto < 2)
+ bd_flushto = 2;
+ } else {
+ /*
+ * We slept and timed out, we can slow down.
+ */
+ bd_flushto += bd_flushinc;
+ if (bd_flushto > hidirtybuffers)
+ bd_flushto = hidirtybuffers;
+ ++bd_flushinc;
+ if (bd_flushinc > hidirtybuffers / 20 + 1)
+ bd_flushinc = hidirtybuffers / 20 + 1;
+ }
/*
- * We calculate how much to add or subtract from bd_flushto
- * and bd_interval based on how far off we are from the
- * optimal number of dirty buffers, which is 20% below the
- * hidirtybuffers mark. We cannot use hidirtybuffers straight
- * because being right on the mark will cause getnewbuf()
- * to oscillate our wakeup.
- *
- * The larger the error in either direction, the more we adjust
- * bd_flushto and bd_interval. The time interval is adjusted
- * by 2 seconds per whole-buffer-range of error. This is an
- * exponential convergence algorithm, with large errors
- * producing large changes and small errors producing small
- * changes.
+ * Set the interval on a linear scale based on hidirtybuffers
+ * with a maximum frequency of 1/10 second.
*/
-
- {
- int brange = hidirtybuffers - lodirtybuffers;
- int middb = hidirtybuffers - brange / 5;
- int deltabuf = middb - numdirtybuffers;
-
- bd_flushto += deltabuf / 20;
- bd_interval += deltabuf * (2 * hz) / (brange * 1);
- }
- if (bd_flushto < lodirtybuffers)
- bd_flushto = lodirtybuffers;
- if (bd_flushto > hidirtybuffers)
- bd_flushto = hidirtybuffers;
+ bd_interval = bd_flushto * 5 * hz / hidirtybuffers;
if (bd_interval < hz / 10)
bd_interval = hz / 10;
- if (bd_interval > 5 * hz)
- bd_interval = 5 * hz;
}
}
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