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authorDavid Vrabel <david.vrabel@citrix.com>2013-04-04 17:21:12 +0000
committerIan Jackson <Ian.Jackson@eu.citrix.com>2013-04-08 17:04:52 +0100
commit48f4af18b3e1e36bf0eda793455ecaea9a316c65 (patch)
tree556900b9852da7b71432178ef968b81b65c0d660
parentb4932b39319229291ff019ba23cab465988e02d8 (diff)
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xl: extend autoballoon xl.conf option with an "auto" option
autoballoon=1 is not recommened if dom0_mem was used to reduce the amount of dom0 memory. Instead of requiring users to change xl.conf if they do this, extend the autoballoon option with a new choice: "auto". With autoballoon="auto", autoballooning will be disabled if dom0_mem was used on the Xen command line. For consistency, accept "on" and "off" as valid autoballoon options (1 and 0 are still accepted). The default remains "on" for now. Signed-off-by: David Vrabel <david.vrabel@citrix.com> Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
-rw-r--r--docs/man/xl.conf.pod.521
-rw-r--r--tools/examples/xl.conf7
-rw-r--r--tools/libxl/xl.c36
3 files changed, 52 insertions, 12 deletions
diff --git a/docs/man/xl.conf.pod.5 b/docs/man/xl.conf.pod.5
index 7b9fcac2fa..a4ce3e529d 100644
--- a/docs/man/xl.conf.pod.5
+++ b/docs/man/xl.conf.pod.5
@@ -45,15 +45,22 @@ The semantics of each C<KEY> defines which form of C<VALUE> is required.
=over 4
-=item B<autoballoon=BOOLEAN>
+=item B<autoballoon="off"|"on"|"auto">
-If disabled then C<xl> will not attempt to reduce the amount of memory
-assigned to domain 0 in order to create free memory when starting a
-new domain. You are strongly recommended to set this to C<0>
-(C<False>) if you use the C<dom0_mem> hypervisor command line to
-reduce the amount of memory given to domain 0 by default.
+If set to "on" then C<xl> will automatically reduce the amount of
+memory assigned to domain 0 in order to free memory for new domains.
-Default: C<1>
+If set to "off" then C<xl> will not automatically reduce the amount of
+domain 0 memory.
+
+If set to "auto" then auto-ballooning will be disabled if the
+C<dom0_mem> option was provided on the Xen command line.
+
+You are strongly recommended to set this to C<"off"> (or C<"auto">) if
+you use the C<dom0_mem> hypervisor command line to reduce the amount
+of memory given to domain 0 by default.
+
+Default: C<"on">
=item B<run_hotplug_scripts=BOOLEAN>
diff --git a/tools/examples/xl.conf b/tools/examples/xl.conf
index b0caa3295b..50cba2bf37 100644
--- a/tools/examples/xl.conf
+++ b/tools/examples/xl.conf
@@ -1,8 +1,9 @@
## Global XL config file ##
-# automatically balloon down dom0 when xen doesn't have enough free
-# memory to create a domain
-#autoballoon=1
+# Control whether dom0 is ballooned down when xen doesn't have enough
+# free memory to create a domain. "auto" means only balloon if dom0
+# starts with all the host's memory.
+#autoballoon="auto"
# full path of the lockfile used by xl during domain creation
#lockfile="/var/lock/xl"
diff --git a/tools/libxl/xl.c b/tools/libxl/xl.c
index 4c598dbbad..ac41fcd294 100644
--- a/tools/libxl/xl.c
+++ b/tools/libxl/xl.c
@@ -26,6 +26,7 @@
#include <fcntl.h>
#include <ctype.h>
#include <inttypes.h>
+#include <regex.h>
#include "libxl.h"
#include "libxl_utils.h"
@@ -48,6 +49,29 @@ enum output_format default_output_format = OUTPUT_FORMAT_JSON;
static xentoollog_level minmsglevel = XTL_PROGRESS;
+/* Get autoballoon option based on presence of dom0_mem Xen command
+ line option. */
+static int auto_autoballoon(void)
+{
+ const libxl_version_info *info;
+ regex_t regex;
+ int ret;
+
+ info = libxl_get_version_info(ctx);
+ if (!info)
+ return 1; /* default to on */
+
+ ret = regcomp(&regex,
+ "(^| )dom0_mem=((|min:|max:)[0-9]+[bBkKmMgG]?,?)+($| )",
+ REG_NOSUB | REG_EXTENDED);
+ if (ret)
+ return 1;
+
+ ret = regexec(&regex, info->commandline, 0, NULL, 0);
+ regfree(&regex);
+ return ret == REG_NOMATCH;
+}
+
static void parse_global_config(const char *configfile,
const char *configfile_data,
int configfile_len)
@@ -69,8 +93,16 @@ static void parse_global_config(const char *configfile,
exit(1);
}
- if (!xlu_cfg_get_long (config, "autoballoon", &l, 0))
- autoballoon = l;
+ if (!xlu_cfg_get_string(config, "autoballoon", &buf, 0)) {
+ if (!strcmp(buf, "on") || !strcmp(buf, "1"))
+ autoballoon = 1;
+ else if (!strcmp(buf, "off") || !strcmp(buf, "0"))
+ autoballoon = 0;
+ else if (!strcmp(buf, "auto"))
+ autoballoon = auto_autoballoon();
+ else
+ fprintf(stderr, "invalid autoballoon option");
+ }
if (!xlu_cfg_get_long (config, "run_hotplug_scripts", &l, 0))
run_hotplug_scripts = l;