This patch addresses bugzilla #649, enabling `xm list' to display the actual amount of memory allocated by a guest. This is done by checking the value that the balloon driver returns after memory requests. As a result, I'm noticing that a guest that I've set to start with 128Mb will actually give the user 126Mb. All other allocations perform normally, and attempting to over-allocate will simply return the amount of space that the domain was able to expand to.
Under the premises that xm list should report actual memory values,
2 tests in xm-test may need to be modified to verify the amount of memory that a guest is physically using, and not rely on the value in the config file as being the amount of memory that the guest will have.
xm-test reactions to patch as of changset 11376:
REASON: Started domain with 128MB, but it got 126 MB
FAIL: 08_create_mem128_pos.test
REASON: Started domain with 256MB, but it got 254 MB
FAIL: 09_create_mem256_pos.test
Running 'free' inside of each guest shows 126, and 254 respectively, not their config file #'s.
Signed-off-by: Tommie McAfee <tommie.mcafee@xxxxxxxxxx>
Regards,
Tommie McAfee
Xen-Testing
------------------------------------------------------------------------
diff -r 593b5623a0d2 linux-2.6-xen-sparse/drivers/xen/balloon/balloon.c
--- a/linux-2.6-xen-sparse/drivers/xen/balloon/balloon.c Fri Sep 29
15:40:35 2006 +0100
+++ b/linux-2.6-xen-sparse/drivers/xen/balloon/balloon.c Wed Oct 04
14:46:33 2006 -0400
@@ -57,6 +57,8 @@
#include <xen/xenbus.h>
#define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10))
+#define NOXENBUS 0
+#define XENBUSREADY 1
#ifdef CONFIG_PROC_FS
static struct proc_dir_entry *balloon_pde;
@@ -83,6 +85,9 @@ extern unsigned long totalram_pages;
/* We may hit the hard limit in Xen. If we do then we remember it. */
static unsigned long hard_limit;
+
+/* Aknowledge that xenstore is available */
+static int xenbus_status;
/*
* Drivers may alter the memory reservation independently, but they must
@@ -325,6 +330,22 @@ static int decrease_reservation(unsigned
return need_sleep;
}
+/* write currently allocated kbs to xenstore */
+static void xenbus_write_xmtarget(void){
+
+ struct xenbus_transaction xbt;
+ unsigned int xm_current_pages;
+
+
+ if(likely(xenbus_status==XENBUSREADY)){
+ xm_current_pages = PAGES2KB(current_pages);
+ xenbus_transaction_start(&xbt);
+ xenbus_printf(xbt,"memory", "xmtarget", "%8u",xm_current_pages);
+ xenbus_transaction_end(xbt,0);
+ }
+
+}
+
/*
* We avoid multiple worker processes conflicting via the balloon mutex.
* We may of course race updates of the target counts (which are protected
@@ -355,6 +376,8 @@ static void balloon_process(void *unused
if (current_target() != current_pages)
mod_timer(&balloon_timer, jiffies + HZ);
+ xenbus_write_xmtarget();
+
up(&balloon_mutex);
}
@@ -384,6 +407,8 @@ static void watch_target(struct xenbus_w
/* This is ok (for domain0 at least) - so just return */
return;
}
+
+ xenbus_status=XENBUSREADY;
/* The given memory/target value is in KiB, so it needs converting to
* pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10.
@@ -462,6 +487,8 @@ static int __init balloon_init(void)
{
unsigned long pfn;
struct page *page;
+
+ xenbus_status=NOXENBUS;
if (!is_running_on_xen())
return -ENODEV;
diff -r 593b5623a0d2 tools/python/xen/xend/XendDomainInfo.py
--- a/tools/python/xen/xend/XendDomainInfo.py Fri Sep 29 15:40:35 2006 +0100
+++ b/tools/python/xen/xend/XendDomainInfo.py Wed Oct 04 14:46:33 2006 -0400
@@ -459,6 +459,7 @@ class XendDomainInfo:
self.console_mfn = None
self.vmWatch = None
+ self.memWatch = None
self.shutdownWatch = None
self.shutdownStartTime = None
@@ -487,6 +488,14 @@ class XendDomainInfo:
return []
+ def xsMemoryChanged(self, _):
+ """Get the memory target from xenstore of this domain.
+ """
+ xs_memory=int(self.readDom('memory/xmtarget'))/1024
+ self.info['memory']=xs_memory
+ self.storeVm("memory", xs_memory)
+ return 1
+
def storeChanged(self, _):
log.trace("XendDomainInfo.storeChanged");
@@ -775,6 +784,9 @@ class XendDomainInfo:
self.vmWatch = xswatch(self.vmpath, self.storeChanged)
self.shutdownWatch = xswatch(self.dompath + '/control/shutdown',
self.handleShutdownWatch)
+ self.memWatch = xswatch(self.dompath + '/memory/xmtarget',
+ self.xsMemoryChanged)
+
def getDomid(self):
@@ -1015,6 +1027,7 @@ class XendDomainInfo:
self.info['memory'] = target
self.storeVm("memory", target)
+ self.storeDom('memory/xmtarget', target << 10)
self.storeDom("memory/target", target << 10)
@@ -1372,6 +1385,7 @@ class XendDomainInfo:
self.refresh_shutdown_lock.acquire()
try:
self.unwatchShutdown()
+ self.unwatchMemory()
self.release_devices()
@@ -1439,6 +1453,18 @@ class XendDomainInfo:
self.shutdownWatch = None
except:
log.exception("Unwatching control/shutdown failed.")
+
+
+ def unwatchMemory(self):
+ """Remove the watch on the domain's control/shutdown node, if any."""
+ try:
+ try:
+ if self.memWatch:
+ self.memWatch.unwatch()
+ finally:
+ self.memWatch= None
+ except:
+ log.exception("Unwatching memory/xmtarget failed.")
## public:
diff -r 593b5623a0d2 tools/python/xen/xend/image.py
--- a/tools/python/xen/xend/image.py Fri Sep 29 15:40:35 2006 +0100
+++ b/tools/python/xen/xend/image.py Wed Oct 04 14:46:33 2006 -0400
@@ -382,6 +382,7 @@ class HVMImageHandler(ImageHandler):
def destroy(self):
self.unregister_shutdown_watch();
+ self.unregister_memory_watch();
import signal
if not self.pid:
return
@@ -406,6 +407,18 @@ class HVMImageHandler(ImageHandler):
log.exception("Unwatching hvm shutdown watch failed.")
self.shutdownWatch = None
log.debug("hvm shutdown watch unregistered")
+
+ def unregister_memory_watch(self):
+ """Remove the watch on the target/xmtarget, if any. Nothrow
+ guarantee."""
+ try:
+ if self.memWatch:
+ self.memWatch.unwatch()
+ except:
+ log.exception("Unwatching memory/xmtarget failed.")
+ self.memWatch = None
+ log.debug("hvm memory watch unregistered")
+
def hvm_shutdown(self, _):
""" watch call back on node control/shutdown,
------------------------------------------------------------------------
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