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authorRichard W.M. Jones <rjones@redhat.com>2009-05-01 11:18:44 +0100
committerRichard W.M. Jones <rjones@redhat.com>2009-05-01 11:18:44 +0100
commit2dc9e8a858b62830d15a8186fe575eb7903d2171 (patch)
tree24cabdc930f88d016db62b0f965667c07d08cfc3
parentac286b26df1aabceca26dac66c325a3676ace4cc (diff)
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Added drop-caches command.
-rw-r--r--daemon/Makefile.am1
-rw-r--r--daemon/dropcaches.c52
-rwxr-xr-xsrc/generator.ml14
3 files changed, 67 insertions, 0 deletions
diff --git a/daemon/Makefile.am b/daemon/Makefile.am
index 9cec685b..569f1ecc 100644
--- a/daemon/Makefile.am
+++ b/daemon/Makefile.am
@@ -29,6 +29,7 @@ guestfsd_SOURCES = \
debug.c \
devsparts.c \
dir.c \
+ dropcaches.c \
ext2.c \
file.c \
fsck.c \
diff --git a/daemon/dropcaches.c b/daemon/dropcaches.c
new file mode 100644
index 00000000..82d95ee2
--- /dev/null
+++ b/daemon/dropcaches.c
@@ -0,0 +1,52 @@
+/* libguestfs - the guestfsd daemon
+ * Copyright (C) 2009 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+
+#include "daemon.h"
+#include "actions.h"
+
+#define PROCFILE "/proc/sys/vm/drop_caches"
+
+int
+do_drop_caches (int what)
+{
+ FILE *fp;
+
+ sync ();
+
+ fp = fopen (PROCFILE, "w");
+ if (fp == NULL) {
+ reply_with_perror (PROCFILE);
+ return -1;
+ }
+
+ fprintf (fp, "%d", what);
+ if (fclose (fp) == EOF) {
+ reply_with_perror (PROCFILE);
+ return -1;
+ }
+
+ return 0;
+}
diff --git a/src/generator.ml b/src/generator.ml
index bb550f1d..2ffe19da 100755
--- a/src/generator.ml
+++ b/src/generator.ml
@@ -1737,6 +1737,20 @@ recursively using the C<cp -a> command.");
This moves a file from C<src> to C<dest> where C<dest> is
either a destination filename or destination directory.");
+ ("drop_caches", (RErr, [Int "whattodrop"]), 90, [],
+ [InitEmpty, TestRun (
+ [["drop_caches"; "3"]])],
+ "drop kernel page cache, dentries and inodes",
+ "\
+This instructs the guest kernel to drop its page cache,
+and/or dentries and inode caches. The parameter C<whattodrop>
+tells the kernel what precisely to drop, see
+L<http://linux-mm.org/Drop_Caches>
+
+Setting C<whattodrop> to 3 should drop everything.
+
+This automatically calls L<sync(2)> before the operation,
+so that the maximum guest memory is freed.");
]