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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /mm/thrash.c
downloadconfigs-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'mm/thrash.c')
-rw-r--r--mm/thrash.c102
1 files changed, 102 insertions, 0 deletions
diff --git a/mm/thrash.c b/mm/thrash.c
new file mode 100644
index 00000000000..11461f7ad83
--- /dev/null
+++ b/mm/thrash.c
@@ -0,0 +1,102 @@
+/*
+ * mm/thrash.c
+ *
+ * Copyright (C) 2004, Red Hat, Inc.
+ * Copyright (C) 2004, Rik van Riel <riel@redhat.com>
+ * Released under the GPL, see the file COPYING for details.
+ *
+ * Simple token based thrashing protection, using the algorithm
+ * described in: http://www.cs.wm.edu/~sjiang/token.pdf
+ */
+#include <linux/jiffies.h>
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/swap.h>
+
+static DEFINE_SPINLOCK(swap_token_lock);
+static unsigned long swap_token_timeout;
+static unsigned long swap_token_check;
+struct mm_struct * swap_token_mm = &init_mm;
+
+#define SWAP_TOKEN_CHECK_INTERVAL (HZ * 2)
+#define SWAP_TOKEN_TIMEOUT 0
+/*
+ * Currently disabled; Needs further code to work at HZ * 300.
+ */
+unsigned long swap_token_default_timeout = SWAP_TOKEN_TIMEOUT;
+
+/*
+ * Take the token away if the process had no page faults
+ * in the last interval, or if it has held the token for
+ * too long.
+ */
+#define SWAP_TOKEN_ENOUGH_RSS 1
+#define SWAP_TOKEN_TIMED_OUT 2
+static int should_release_swap_token(struct mm_struct *mm)
+{
+ int ret = 0;
+ if (!mm->recent_pagein)
+ ret = SWAP_TOKEN_ENOUGH_RSS;
+ else if (time_after(jiffies, swap_token_timeout))
+ ret = SWAP_TOKEN_TIMED_OUT;
+ mm->recent_pagein = 0;
+ return ret;
+}
+
+/*
+ * Try to grab the swapout protection token. We only try to
+ * grab it once every TOKEN_CHECK_INTERVAL, both to prevent
+ * SMP lock contention and to check that the process that held
+ * the token before is no longer thrashing.
+ */
+void grab_swap_token(void)
+{
+ struct mm_struct *mm;
+ int reason;
+
+ /* We have the token. Let others know we still need it. */
+ if (has_swap_token(current->mm)) {
+ current->mm->recent_pagein = 1;
+ return;
+ }
+
+ if (time_after(jiffies, swap_token_check)) {
+
+ /* Can't get swapout protection if we exceed our RSS limit. */
+ // if (current->mm->rss > current->mm->rlimit_rss)
+ // return;
+
+ /* ... or if we recently held the token. */
+ if (time_before(jiffies, current->mm->swap_token_time))
+ return;
+
+ if (!spin_trylock(&swap_token_lock))
+ return;
+
+ swap_token_check = jiffies + SWAP_TOKEN_CHECK_INTERVAL;
+
+ mm = swap_token_mm;
+ if ((reason = should_release_swap_token(mm))) {
+ unsigned long eligible = jiffies;
+ if (reason == SWAP_TOKEN_TIMED_OUT) {
+ eligible += swap_token_default_timeout;
+ }
+ mm->swap_token_time = eligible;
+ swap_token_timeout = jiffies + swap_token_default_timeout;
+ swap_token_mm = current->mm;
+ }
+ spin_unlock(&swap_token_lock);
+ }
+ return;
+}
+
+/* Called on process exit. */
+void __put_swap_token(struct mm_struct *mm)
+{
+ spin_lock(&swap_token_lock);
+ if (likely(mm == swap_token_mm)) {
+ swap_token_mm = &init_mm;
+ swap_token_check = jiffies;
+ }
+ spin_unlock(&swap_token_lock);
+}