diff options
Diffstat (limited to 'trunk/2.6.22/20054_xen-balloon-min.patch1')
| -rw-r--r-- | trunk/2.6.22/20054_xen-balloon-min.patch1 | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/trunk/2.6.22/20054_xen-balloon-min.patch1 b/trunk/2.6.22/20054_xen-balloon-min.patch1 new file mode 100644 index 0000000..ddd3cdf --- /dev/null +++ b/trunk/2.6.22/20054_xen-balloon-min.patch1 @@ -0,0 +1,77 @@ +From: ksrinivasan@novell.com +Subject: Don't allow ballooning down a domain below a reasonable limit. +References: 172482 + +Reasonable is hard to judge; we don't want to disallow small domains. +But the system needs a reasonable amount of memory to perform its +duties, set up tables, etc. If on the other hand, the admin is able +to set up and boot up correctly a very small domain, there's no point +in forcing it to be larger. +We end up with some kind of logarithmic function, approximated. + +Memory changes are logged, so making domains too small should at least +result in a trace. + +Signed-off-by: Kurt Garloff <garloff@suse.de> + +Index: head-2007-10-08/drivers/xen/balloon/balloon.c +=================================================================== +--- head-2007-10-08.orig/drivers/xen/balloon/balloon.c 2007-10-09 09:31:50.000000000 +0200 ++++ head-2007-10-08/drivers/xen/balloon/balloon.c 2007-10-09 09:32:02.000000000 +0200 +@@ -181,6 +181,38 @@ static unsigned long current_target(void + return target; + } + ++static unsigned long minimum_target(void) ++{ ++ unsigned long min_pages; ++ unsigned long curr_pages = current_target(); ++ ++#define MB2PAGES(mb) ((mb) << (20 - PAGE_SHIFT)) ++ /* Simple continuous piecewiese linear function: ++ * max MiB -> min MiB gradient ++ * 0 0 ++ * 16 16 ++ * 32 24 ++ * 128 72 (1/2) ++ * 512 168 (1/4) ++ * 2048 360 (1/8) ++ * 8192 552 (1/32) ++ * 32768 1320 ++ * 131072 4392 ++ */ ++ if (max_pfn < MB2PAGES(128)) ++ min_pages = MB2PAGES(8) + (max_pfn >> 1); ++ else if (max_pfn < MB2PAGES(512)) ++ min_pages = MB2PAGES(40) + (max_pfn >> 2); ++ else if (max_pfn < MB2PAGES(2048)) ++ min_pages = MB2PAGES(104) + (max_pfn >> 3); ++ else ++ min_pages = MB2PAGES(296) + (max_pfn >> 5); ++#undef MB2PAGES ++ ++ /* Don't enforce growth */ ++ return min_pages < curr_pages ? min_pages : curr_pages; ++} ++ + static int increase_reservation(unsigned long nr_pages) + { + unsigned long pfn, i, flags; +@@ -369,6 +401,17 @@ static void balloon_process(struct work_ + /* Resets the Xen limit, sets new target, and kicks off processing. */ + void balloon_set_new_target(unsigned long target) + { ++ /* First make sure that we are not lowering the value below the ++ * "minimum". ++ */ ++ unsigned long min_pages = minimum_target(); ++ ++ if (target < min_pages) ++ target = min_pages; ++ ++ printk(KERN_INFO "Setting mem allocation to %lu kiB\n", ++ PAGES2KB(target)); ++ + /* No need for lock. Not read-modify-write updates. */ + bs.hard_limit = ~0UL; + bs.target_pages = target; |