[Xen-changelog] [xen-unstable] xenpaging: retry unpageable gfns

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Olaf Hering <olaf@xxxxxxxxx>
# Date 1321804961 -3600
# Node ID 8eba32b9598cdc60bdc4b446cbc8446078e37c04
# Parent  a2b4ae2becdf71c8d75cc34fcd56558632f757b4
xenpaging: retry unpageable gfns

Nomination of gfns can fail, but may succeed later.
Thats the case for a guest that starts ballooned.

v2:
 - print debug when clearing uncosumed happens

Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
---


diff -r a2b4ae2becdf -r 8eba32b9598c tools/xenpaging/policy_default.c
--- a/tools/xenpaging/policy_default.c  Sun Nov 20 17:02:40 2011 +0100
+++ b/tools/xenpaging/policy_default.c  Sun Nov 20 17:02:41 2011 +0100
@@ -32,6 +32,7 @@
 static unsigned int mru_size;
 static unsigned long *bitmap;
 static unsigned long *unconsumed;
+static unsigned int unconsumed_cleared;
 static unsigned long current_gfn;
 static unsigned long max_pages;
 
@@ -87,8 +88,21 @@
         current_gfn++;
         if ( current_gfn >= max_pages )
             current_gfn = 0;
+        /* Could not nominate any gfn */
         if ( wrap == current_gfn )
         {
+            /* Count wrap arounds */
+            unconsumed_cleared++;
+            /* Force retry every few seconds (depends on poll() timeout) */
+            if ( unconsumed_cleared > 123)
+            {
+                /* Force retry of unconsumed gfns */
+                bitmap_clear(unconsumed, max_pages);
+                unconsumed_cleared = 0;
+                DPRINTF("clearing unconsumed, wrap %lx", wrap);
+                /* One more round before returning ENOSPC */
+                continue;
+            }
             victim->gfn = INVALID_MFN;
             return -ENOSPC;
         }

_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-changelog