Changeset 82

Timestamp:

06/29/05 03:06:17 (4 years ago)

Author:

jtv

Message:

Redesigned policy state machine, now in its own file

Files:

• debian/changelog (modified) (1 diff)
• src/Makefile (modified) (2 diffs)
• src/main.c (modified) (2 diffs)
• src/state.c (added)
• src/state.h (added)
• src/swaps.c (modified) (13 diffs)
• src/swaps.h (modified) (2 diffs)

debian/changelog

@@ +1 @@
+swapspace (1.5) unstable; urgency=low
+
+  * Redesigned internal state machine, should improve corner-case behaviour
+
+ -- Jeroen T. Vermeulen <jtv@sipa.or.th>  Wed, 29 June 2005 14:10:00 +0700
+
-swapspace (1.4) unstable; urgency=low
-

src/Makefile

@@ -9 +9 @@
-
-
-
+tate.o s
-
-swapspace : $(SWAPSPACEOBJS)
@@ -24 +24 @@
-opts.o : opts.c opts.h main.h ../VERSION ../DATE
-
+state.o : state.c state.h main.h memory.h support.h swaps.h
+
-support.o : support.c config.h env.h support.h
-
-
+tate.h s
-
-clean :

src/main.c

@@ -39 +39 @@
-#include "memory.h"
-#include "opts.h"
+#include "state.h"
-#include "support.h"
-#include "swaps.h"
@@ -197 +198 @@
-{
-  // TODO: TODO: TODO:
-}
-
-
-static void handle_requirements(void)
-{
-  const memsize_t req = memory_target();
-  if (req > 0)          alloc_swapfile(req);
-  else if (req < 0)     free_swapfile(-req);
-  else                  steady_state();
-}
-

src/swaps.c

@@ -36 +36 @@
-#include "log.h"
-#include "opts.h"
+#include "state.h"
-#include "support.h"
-#include "swaps.h"
@@ -69 +70 @@
-
-
-// TODO: Make this adaptive
-/// Minimum cooldown time between Bull/Bear policy reversals
-/** The program's disposition to allocate or deallocate wavers between two
- * extremes: Bull and Bear.  This is done to avoid unstable behaviour where swap
- * files are repeatedly created, deleted again, and then re-allocated.
- *
- * During Bull phases more swap space may be allocated to meet demand, but no
- * deallocations are made regardless of how much swap or memory space is being
- * left unused.  While this phase lasts, the program will assume that any drop
- * in swap space usage may be temporary and the allocated swap files may be
- * needed again soon.  Bull phases can end only if the disk fills up with swap
- * files, or the amount of free memory remains above the deallocation threshold
- * for an entire cooldown period.
- *
- * On the other extreme, Bear phases occur when swapfile allocation fails due
- * to lack of disk space.  Once we get to that stage, allocating yet more swap
- * space is not likely to satisfy whatever software is using up so much memory
- * or disk space.  In a Bear phase we assume that the spike in memory usage is a
- * fluke: no more allocations are attempted--hopefully starving the offending
- * software--and unneeded swap space is freed up more aggressively.
- *
- * Deallocation does not trigger a transition, though it may conceivably provide
- * useful information about optimal phase duration.
- */
-static time_t cooldown_time = 600;
-
-char *set_min_swapsize(long long size)
-{
@@ -104 +79 @@
-{
-  max_swapsize = TRUNC_TO_PAGE(size);
-  return NULL;
-}
-
-char *set_cooldown(long long duration)
-{
-  cooldown_time = (time_t)duration;
-  return NULL;
-}
@@ -142 +111 @@
-
-  return true;
-}
-
-
-/// Timestamp of most recent attempt to allocate a swapfile
-static time_t cooldown_start = 0;
-
-/// Did the last attempt at swapfile allocation trigger a Bear phase?
-static bool cooldown_bear = false;
-
-
-static inline bool in_cooldown(void)
-{
-  return (clock < cooldown_start + cooldown_time);
-}
-
-
-void steady_state(void)
-{
-  if (!cooldown_bear) cooldown_start = clock;
-}
-
@@ -197 +147 @@
-  // TODO: Allow this to go to logfile
-  printf("clock: %lld\t", (long long)clock);
-
-
-
-
-
-
-
-
-
-
-
+
-
-  // TODO: Print memory overview, and include percentages
-
-" "
+
-  for (int i=0; i<MAX_SWAPFILES; ++i)
-    if (swapfiles[i].size)
@@ -218 +158 @@
-          swapfiles[i].size,
-          swapfiles[i].used);
+  puts("---");
-}
-
@@ -281 +222 @@
-      // Disk full.  Don't create swapfiles for a while.
-      bytes = 0;
-      cooldown_bear = true;
-      cooldown_start = clock;
-      break;
-    }
-  }
-  else
-  {
-    cooldown_start = clock;
-  }
-
@@ -315 +250 @@
-  if (unlikely(size < min_swapsize)) return 0;
-
-  // Don't allocate swap for a while--we had a bad experience recently
-  if (unlikely(cooldown_bear) && in_cooldown()) return 0;
-
-  size = MIN(size, max_swapsize);
-
@@ -332 +264 @@
-  {
-    unlink(file);
-
+real
-  }
-  
@@ -614 +546 @@
-
-
-void
+bool
-{
-  /* Round request to page size, then add a bit for swapfile overhead.  Clever
@@ -621 +553 @@
-  size = TRUNC_TO_PAGE(size) + 2*PAGE_SIZE;
-  const int newswap = find_free(sequence_number);
-
+ false
-
-  // We can allocate another swapfile.  Great.
@@ -631 +563 @@
-  if (swapfiles[newswap].size)
-  {
-
-
-
+
+
+
+
+
+
+
+
+
-}
-
@@ -639 +577 @@
-void free_swapfile(memsize_t maxsize)
-{
-
-
-
-
-
-
+
+
+

src/swaps.h

@@ -54 +54 @@
-/**
- * @param size number of bytes to allocate
+ * @return success
- */
-void
+bool
-
-/// Free swap space
@@ -62 +63 @@
- */
-void free_swapfile(memsize_t maxsize);
-
-/// Mark an iteration where we don't want to allocate/deallocate swap files 
-void steady_state(void);
-
-char *set_min_swapsize(long long size);