* How does the self-ballooning daemon calculate the selftarget?
@ 2009-11-10 16:23 Jia Rao
2009-11-10 17:43 ` Dan Magenheimer
0 siblings, 1 reply; 6+ messages in thread
From: Jia Rao @ 2009-11-10 16:23 UTC (permalink / raw)
To: xen-devel
[-- Attachment #1.1: Type: text/plain, Size: 1570 bytes --]
Hi all,
I am wondering how does the self-ballooning daemon calculate the selftarget
for the guest OS.
>From the README of balloon driver, it seems that selftarget is determined by
Committed_AS in meminfo.
I did some test on tpcc benchmark. the OS is initially allocated 2048MB of
memory, and then I enabled the selfballooning by echo 1 > /proc/xen/balloon.
The configuration of xenballoond.conf is the default except that I enabled
self-balloon.
The following is the meminfo
MemTotal: 1939996 kB
MemFree: 1183888 kB
Buffers: 13260 kB
Cached: 396492 kB
SwapCached: 0 kB
Active: 386912 kB
Inactive: 213584 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 1939996 kB
LowFree: 1183888 kB
SwapTotal: 2097136 kB
SwapFree: 2097132 kB
Dirty: 78432 kB
Writeback: 0 kB
AnonPages: 190668 kB
Mapped: 14228 kB
Slab: 53148 kB
PageTables: 4836 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
CommitLimit: 3067132 kB
Committed_AS: 524484 kB
VmallocTotal: 34359738367 kB
VmallocUsed: 1208 kB
VmallocChunk: 34359737159 kB
It seems that the self-balloon driver is reluctant to give up free memory
from the guest although the Committed_AS is small. The self-ballooning did
changed the selftarget to something like 1.6GB but quickly changed to and
fix at 193xxxxKB.
According to the meminfo, we should be able to give up at least 800MB back
to the VMM.
FYI: xen 3.3.1, linux 2.6.18.8 in both dom0 and domu.
Any ideas?
Thanks,
Jia
[-- Attachment #1.2: Type: text/html, Size: 1725 bytes --]
[-- Attachment #2: Type: text/plain, Size: 138 bytes --]
_______________________________________________
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http://lists.xensource.com/xen-devel
^ permalink raw reply [flat|nested] 6+ messages in thread
* RE: How does the self-ballooning daemon calculate the selftarget?
2009-11-10 16:23 How does the self-ballooning daemon calculate the selftarget? Jia Rao
@ 2009-11-10 17:43 ` Dan Magenheimer
2009-11-10 19:18 ` Jia Rao
0 siblings, 1 reply; 6+ messages in thread
From: Dan Magenheimer @ 2009-11-10 17:43 UTC (permalink / raw)
To: Jia Rao, xen-devel
Hi Jia --
There are changes in newer versions of the balloon driver to
ensure that ballooning does not take too much memory away
from the kernel, which would result in kernel crashes.
These changes set a different minimum value depending on
how much memory the kernel originally discovered.
If the self-ballooning scripts run with an "old" balloon
driver and one changes certain parameters
in the scripts, kernel crashes might occur. So the
self-ballooning scripts implement a minimum memory
algorithm similar to the newer balloon driver to
avoid this situation.
Look for XENBALLOON_MINMEM in the xenballoon config file
if you want to change this.
Dan
-----Original Message-----
From: Jia Rao [mailto:rickenrao@gmail.com]
Sent: Tuesday, November 10, 2009 9:23 AM
To: xen-devel@lists.xensource.com
Subject: [Xen-devel] How does the self-ballooning daemon calculate the selftarget?
Hi all,
I am wondering how does the self-ballooning daemon calculate the selftarget for the guest OS.
>From the README of balloon driver, it seems that selftarget is determined by Committed_AS in meminfo.
I did some test on tpcc benchmark. the OS is initially allocated 2048MB of memory, and then I enabled the selfballooning by echo 1 > /proc/xen/balloon.
The configuration of xenballoond.conf is the default except that I enabled self-balloon.
The following is the meminfo
MemTotal: 1939996 kB
MemFree: 1183888 kB
Buffers: 13260 kB
Cached: 396492 kB
SwapCached: 0 kB
Active: 386912 kB
Inactive: 213584 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 1939996 kB
LowFree: 1183888 kB
SwapTotal: 2097136 kB
SwapFree: 2097132 kB
Dirty: 78432 kB
Writeback: 0 kB
AnonPages: 190668 kB
Mapped: 14228 kB
Slab: 53148 kB
PageTables: 4836 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
CommitLimit: 3067132 kB
Committed_AS: 524484 kB
VmallocTotal: 34359738367 kB
VmallocUsed: 1208 kB
VmallocChunk: 34359737159 kB
It seems that the self-balloon driver is reluctant to give up free memory from the guest although the Committed_AS is small. The self-ballooning did changed the selftarget to something like 1.6GB but quickly changed to and fix at 193xxxxKB.
According to the meminfo, we should be able to give up at least 800MB back to the VMM.
FYI: xen 3.3.1, linux 2.6.18.8 in both dom0 and domu.
Any ideas?
Thanks,
Jia
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: How does the self-ballooning daemon calculate the selftarget?
2009-11-10 17:43 ` Dan Magenheimer
@ 2009-11-10 19:18 ` Jia Rao
2009-11-10 20:45 ` Dan Magenheimer
0 siblings, 1 reply; 6+ messages in thread
From: Jia Rao @ 2009-11-10 19:18 UTC (permalink / raw)
To: Dan Magenheimer; +Cc: xen-devel
[-- Attachment #1.1: Type: text/plain, Size: 3525 bytes --]
Hi Dan,
Thanks for the reply.
The XENBALLOON_MINMEM was set to 0 in my case.
I am wondering if the /proc/meminfo is a reliable source for memory
utilization of a guest. In my case, the guest stays in idle for several
hours, the metrics in /proc/meminfo is seldom changed.
For example, the Committed_AS and Active metrics stay almost the same for
several hours.
In earlier kernels, the Active and Inactive metrics are periodically updated
by a kernel thread kscand, which seems to has been removed from the 2.6
kernel.
>From what I have observed, the meminfo is correctly updated if the memory
demand from the guest is increasing. However, once the memory demand drops
or be almost zero (idle), the meminfo is not periodically updated. This
might be a problem for the self-balloon daemon to deflate the balloon.
Thanks,
Jia
On Tue, Nov 10, 2009 at 12:43 PM, Dan Magenheimer <
dan.magenheimer@oracle.com> wrote:
> Hi Jia --
>
> There are changes in newer versions of the balloon driver to
> ensure that ballooning does not take too much memory away
> from the kernel, which would result in kernel crashes.
> These changes set a different minimum value depending on
> how much memory the kernel originally discovered.
>
> If the self-ballooning scripts run with an "old" balloon
> driver and one changes certain parameters
> in the scripts, kernel crashes might occur. So the
> self-ballooning scripts implement a minimum memory
> algorithm similar to the newer balloon driver to
> avoid this situation.
>
> Look for XENBALLOON_MINMEM in the xenballoon config file
> if you want to change this.
>
> Dan
>
> -----Original Message-----
> From: Jia Rao [mailto:rickenrao@gmail.com]
> Sent: Tuesday, November 10, 2009 9:23 AM
> To: xen-devel@lists.xensource.com
> Subject: [Xen-devel] How does the self-ballooning daemon calculate the
> selftarget?
>
>
> Hi all,
>
> I am wondering how does the self-ballooning daemon calculate the selftarget
> for the guest OS.
> From the README of balloon driver, it seems that selftarget is determined
> by Committed_AS in meminfo.
>
> I did some test on tpcc benchmark. the OS is initially allocated 2048MB of
> memory, and then I enabled the selfballooning by echo 1 > /proc/xen/balloon.
> The configuration of xenballoond.conf is the default except that I enabled
> self-balloon.
>
> The following is the meminfo
>
> MemTotal: 1939996 kB
> MemFree: 1183888 kB
> Buffers: 13260 kB
> Cached: 396492 kB
> SwapCached: 0 kB
> Active: 386912 kB
> Inactive: 213584 kB
> HighTotal: 0 kB
> HighFree: 0 kB
> LowTotal: 1939996 kB
> LowFree: 1183888 kB
> SwapTotal: 2097136 kB
> SwapFree: 2097132 kB
> Dirty: 78432 kB
> Writeback: 0 kB
> AnonPages: 190668 kB
> Mapped: 14228 kB
> Slab: 53148 kB
> PageTables: 4836 kB
> NFS_Unstable: 0 kB
> Bounce: 0 kB
> CommitLimit: 3067132 kB
> Committed_AS: 524484 kB
> VmallocTotal: 34359738367 kB
> VmallocUsed: 1208 kB
> VmallocChunk: 34359737159 kB
>
> It seems that the self-balloon driver is reluctant to give up free memory
> from the guest although the Committed_AS is small. The self-ballooning did
> changed the selftarget to something like 1.6GB but quickly changed to and
> fix at 193xxxxKB.
>
> According to the meminfo, we should be able to give up at least 800MB back
> to the VMM.
> FYI: xen 3.3.1, linux 2.6.18.8 in both dom0 and domu.
>
> Any ideas?
>
> Thanks,
> Jia
>
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_______________________________________________
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http://lists.xensource.com/xen-devel
^ permalink raw reply [flat|nested] 6+ messages in thread
* RE: How does the self-ballooning daemon calculate the selftarget?
2009-11-10 19:18 ` Jia Rao
@ 2009-11-10 20:45 ` Dan Magenheimer
2009-11-11 1:21 ` Jia Rao
0 siblings, 1 reply; 6+ messages in thread
From: Dan Magenheimer @ 2009-11-10 20:45 UTC (permalink / raw)
To: Jia Rao; +Cc: xen-devel
[-- Attachment #1.1: Type: text/plain, Size: 4977 bytes --]
Hi Jia --
First, please note that when XENBALLOON_MINMEM is set to 0, that does NOT mean 0MB. As described in the text in the xenballoon config file, XENBALLOON_MINMEM==0 means that the heuristic is used which is in my previous reply.
As for Committed_AS, it is certainly not a perfect metric. It was just an adequate one (and much better than no metric at all).
I'm not sure, but your observation of meminfo not being periodically updated may be a result of a balloon driver bug that was fixed in a patch by Ian Campbell here:
http://xenbits.xensource.com/linux-2.6.18-xen.hg?rev/329ea0ccb344
If you are interested in the area of memory utilization optimization, I'd encourage you to try tmem, which is in xen-unstable and the Oracle VM 2.2 product. (See http://oss.oracle.com/projects/tmem for more info.)
Dan
P.S. The minimum memory heuristic patch for the balloon driver is here:
http://xenbits.xensource.com/linux-2.6.18-xen.hg?rev/b61443b1bf76
-----Original Message-----
From: Jia Rao [mailto:rickenrao@gmail.com]
Sent: Tuesday, November 10, 2009 12:19 PM
To: Dan Magenheimer
Cc: xen-devel@lists.xensource.com
Subject: Re: [Xen-devel] How does the self-ballooning daemon calculate the selftarget?
Hi Dan,
Thanks for the reply.
The XENBALLOON_MINMEM was set to 0 in my case.
I am wondering if the /proc/meminfo is a reliable source for memory utilization of a guest. In my case, the guest stays in idle for several hours, the metrics in /proc/meminfo is seldom changed.
For example, the Committed_AS and Active metrics stay almost the same for several hours.
In earlier kernels, the Active and Inactive metrics are periodically updated by a kernel thread kscand, which seems to has been removed from the 2.6 kernel.
From what I have observed, the meminfo is correctly updated if the memory demand from the guest is increasing. However, once the memory demand drops or be almost zero (idle), the meminfo is not periodically updated. This might be a problem for the self-balloon daemon to deflate the balloon.
Thanks,
Jia
On Tue, Nov 10, 2009 at 12:43 PM, Dan Magenheimer <dan.magenheimer@oracle.com> wrote:
Hi Jia --
There are changes in newer versions of the balloon driver to
ensure that ballooning does not take too much memory away
from the kernel, which would result in kernel crashes.
These changes set a different minimum value depending on
how much memory the kernel originally discovered.
If the self-ballooning scripts run with an "old" balloon
driver and one changes certain parameters
in the scripts, kernel crashes might occur. So the
self-ballooning scripts implement a minimum memory
algorithm similar to the newer balloon driver to
avoid this situation.
Look for XENBALLOON_MINMEM in the xenballoon config file
if you want to change this.
Dan
-----Original Message-----
From: Jia Rao [mailto:rickenrao@gmail.com]
Sent: Tuesday, November 10, 2009 9:23 AM
To: xen-devel@lists.xensource.com
Subject: [Xen-devel] How does the self-ballooning daemon calculate the selftarget?
Hi all,
I am wondering how does the self-ballooning daemon calculate the selftarget for the guest OS.
>From the README of balloon driver, it seems that selftarget is determined by Committed_AS in meminfo.
I did some test on tpcc benchmark. the OS is initially allocated 2048MB of memory, and then I enabled the selfballooning by echo 1 > /proc/xen/balloon.
The configuration of xenballoond.conf is the default except that I enabled self-balloon.
The following is the meminfo
MemTotal: 1939996 kB
MemFree: 1183888 kB
Buffers: 13260 kB
Cached: 396492 kB
SwapCached: 0 kB
Active: 386912 kB
Inactive: 213584 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 1939996 kB
LowFree: 1183888 kB
SwapTotal: 2097136 kB
SwapFree: 2097132 kB
Dirty: 78432 kB
Writeback: 0 kB
AnonPages: 190668 kB
Mapped: 14228 kB
Slab: 53148 kB
PageTables: 4836 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
CommitLimit: 3067132 kB
Committed_AS: 524484 kB
VmallocTotal: 34359738367 kB
VmallocUsed: 1208 kB
VmallocChunk: 34359737159 kB
It seems that the self-balloon driver is reluctant to give up free memory from the guest although the Committed_AS is small. The self-ballooning did changed the selftarget to something like 1.6GB but quickly changed to and fix at 193xxxxKB.
According to the meminfo, we should be able to give up at least 800MB back to the VMM.
FYI: xen 3.3.1, linux 2.6.18.8 in both dom0 and domu.
Any ideas?
Thanks,
Jia
[-- Attachment #1.2: Type: text/html, Size: 8297 bytes --]
[-- Attachment #2: Type: text/plain, Size: 138 bytes --]
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: How does the self-ballooning daemon calculate the selftarget?
2009-11-10 20:45 ` Dan Magenheimer
@ 2009-11-11 1:21 ` Jia Rao
2009-11-11 3:08 ` Dan Magenheimer
0 siblings, 1 reply; 6+ messages in thread
From: Jia Rao @ 2009-11-11 1:21 UTC (permalink / raw)
To: Dan Magenheimer; +Cc: xen-devel
[-- Attachment #1.1: Type: text/plain, Size: 5379 bytes --]
Hi Dan,
That is because the bug you mentioned here. I ran my guest under my friend's
xen 3.4 which has a updated 2.6.18.8 dom0, the self ballooning worked fine
(I didnt patch the guest kernel).
I am going to patch the fix by Ian Campbell in my xen 3.3 machines.
Do I need to patch the guest kernel too? or just patch the dom0 kernel?
Thanks,
Jia
On Tue, Nov 10, 2009 at 3:45 PM, Dan Magenheimer <dan.magenheimer@oracle.com
> wrote:
> Hi Jia --
>
> First, please note that when XENBALLOON_MINMEM is set to 0, that does NOT
> mean 0MB. As described in the text in the xenballoon config
> file, XENBALLOON_MINMEM==0 means that the heuristic is used which is in my
> previous reply.
>
> As for Committed_AS, it is certainly not a perfect metric. It was just an
> adequate one (and much better than no metric at all).
>
> I'm not sure, but your observation of meminfo not being periodically
> updated may be a result of a balloon driver bug that was fixed in a patch by
> Ian Campbell here:
>
> http://xenbits.xensource.com/linux-2.6.18-xen.hg?rev/329ea0ccb344
>
> If you are interested in the area of memory utilization optimization, I'd
> encourage you to try tmem, which is in xen-unstable and the Oracle VM 2.2
> product. (See http://oss.oracle.com/projects/tmem for more info.)
>
> Dan
>
> P.S. The minimum memory heuristic patch for the balloon driver is here:
>
> http://xenbits.xensource.com/linux-2.6.18-xen.hg?rev/b61443b1bf76
>
> -----Original Message-----
> *From:* Jia Rao [mailto:rickenrao@gmail.com]
> *Sent:* Tuesday, November 10, 2009 12:19 PM
> *To:* Dan Magenheimer
> *Cc:* xen-devel@lists.xensource.com
> *Subject:* Re: [Xen-devel] How does the self-ballooning daemon calculate
> the selftarget?
>
> Hi Dan,
>
> Thanks for the reply.
> The XENBALLOON_MINMEM was set to 0 in my case.
>
> I am wondering if the /proc/meminfo is a reliable source for memory
> utilization of a guest. In my case, the guest stays in idle for several
> hours, the metrics in /proc/meminfo is seldom changed.
> For example, the Committed_AS and Active metrics stay almost the same for
> several hours.
>
> In earlier kernels, the Active and Inactive metrics are periodically
> updated by a kernel thread kscand, which seems to has been removed from the
> 2.6 kernel.
>
> From what I have observed, the meminfo is correctly updated if the memory
> demand from the guest is increasing. However, once the memory demand drops
> or be almost zero (idle), the meminfo is not periodically updated. This
> might be a problem for the self-balloon daemon to deflate the balloon.
>
> Thanks,
> Jia
>
> On Tue, Nov 10, 2009 at 12:43 PM, Dan Magenheimer <
> dan.magenheimer@oracle.com> wrote:
>
>> Hi Jia --
>>
>> There are changes in newer versions of the balloon driver to
>> ensure that ballooning does not take too much memory away
>> from the kernel, which would result in kernel crashes.
>> These changes set a different minimum value depending on
>> how much memory the kernel originally discovered.
>>
>> If the self-ballooning scripts run with an "old" balloon
>> driver and one changes certain parameters
>> in the scripts, kernel crashes might occur. So the
>> self-ballooning scripts implement a minimum memory
>> algorithm similar to the newer balloon driver to
>> avoid this situation.
>>
>> Look for XENBALLOON_MINMEM in the xenballoon config file
>> if you want to change this.
>>
>> Dan
>>
>> -----Original Message-----
>> From: Jia Rao [mailto:rickenrao@gmail.com]
>> Sent: Tuesday, November 10, 2009 9:23 AM
>> To: xen-devel@lists.xensource.com
>> Subject: [Xen-devel] How does the self-ballooning daemon calculate the
>> selftarget?
>>
>>
>> Hi all,
>>
>> I am wondering how does the self-ballooning daemon calculate the
>> selftarget for the guest OS.
>> >From the README of balloon driver, it seems that selftarget is determined
>> by Committed_AS in meminfo.
>>
>> I did some test on tpcc benchmark. the OS is initially allocated 2048MB of
>> memory, and then I enabled the selfballooning by echo 1 > /proc/xen/balloon.
>> The configuration of xenballoond.conf is the default except that I enabled
>> self-balloon.
>>
>> The following is the meminfo
>>
>> MemTotal: 1939996 kB
>> MemFree: 1183888 kB
>> Buffers: 13260 kB
>> Cached: 396492 kB
>> SwapCached: 0 kB
>> Active: 386912 kB
>> Inactive: 213584 kB
>> HighTotal: 0 kB
>> HighFree: 0 kB
>> LowTotal: 1939996 kB
>> LowFree: 1183888 kB
>> SwapTotal: 2097136 kB
>> SwapFree: 2097132 kB
>> Dirty: 78432 kB
>> Writeback: 0 kB
>> AnonPages: 190668 kB
>> Mapped: 14228 kB
>> Slab: 53148 kB
>> PageTables: 4836 kB
>> NFS_Unstable: 0 kB
>> Bounce: 0 kB
>> CommitLimit: 3067132 kB
>> Committed_AS: 524484 kB
>> VmallocTotal: 34359738367 kB
>> VmallocUsed: 1208 kB
>> VmallocChunk: 34359737159 kB
>>
>> It seems that the self-balloon driver is reluctant to give up free memory
>> from the guest although the Committed_AS is small. The self-ballooning did
>> changed the selftarget to something like 1.6GB but quickly changed to and
>> fix at 193xxxxKB.
>>
>> According to the meminfo, we should be able to give up at least 800MB back
>> to the VMM.
>> FYI: xen 3.3.1, linux 2.6.18.8 in both dom0 and domu.
>>
>> Any ideas?
>>
>> Thanks,
>> Jia
>>
>
>
[-- Attachment #1.2: Type: text/html, Size: 8281 bytes --]
[-- Attachment #2: Type: text/plain, Size: 138 bytes --]
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel
^ permalink raw reply [flat|nested] 6+ messages in thread
* RE: How does the self-ballooning daemon calculate the selftarget?
2009-11-11 1:21 ` Jia Rao
@ 2009-11-11 3:08 ` Dan Magenheimer
0 siblings, 0 replies; 6+ messages in thread
From: Dan Magenheimer @ 2009-11-11 3:08 UTC (permalink / raw)
To: Jia Rao; +Cc: xen-devel
[-- Attachment #1.1: Type: text/plain, Size: 6232 bytes --]
Hmmmm... I think Ian Campbell's patch needs to be applied in the guest. So it is a mystery to me why your guest worked on your friend's 3.4 machine and not on your 3.3 machine.
-----Original Message-----
From: Jia Rao [mailto:rickenrao@gmail.com]
Sent: Tuesday, November 10, 2009 6:22 PM
To: Dan Magenheimer
Cc: xen-devel@lists.xensource.com
Subject: Re: [Xen-devel] How does the self-ballooning daemon calculate the selftarget?
Hi Dan,
That is because the bug you mentioned here. I ran my guest under my friend's xen 3.4 which has a updated 2.6.18.8 dom0, the self ballooning worked fine (I didnt patch the guest kernel).
I am going to patch the fix by Ian Campbell in my xen 3.3 machines.
Do I need to patch the guest kernel too? or just patch the dom0 kernel?
Thanks,
Jia
On Tue, Nov 10, 2009 at 3:45 PM, Dan Magenheimer <dan.magenheimer@oracle.com> wrote:
Hi Jia --
First, please note that when XENBALLOON_MINMEM is set to 0, that does NOT mean 0MB. As described in the text in the xenballoon config file, XENBALLOON_MINMEM==0 means that the heuristic is used which is in my previous reply.
As for Committed_AS, it is certainly not a perfect metric. It was just an adequate one (and much better than no metric at all).
I'm not sure, but your observation of meminfo not being periodically updated may be a result of a balloon driver bug that was fixed in a patch by Ian Campbell here:
http://xenbits.xensource.com/linux-2.6.18-xen.hg?rev/329ea0ccb344
If you are interested in the area of memory utilization optimization, I'd encourage you to try tmem, which is in xen-unstable and the Oracle VM 2.2 product. (See http://oss.oracle.com/projects/tmem for more info.)
Dan
P.S. The minimum memory heuristic patch for the balloon driver is here:
http://xenbits.xensource.com/linux-2.6.18-xen.hg?rev/b61443b1bf76
-----Original Message-----
From: Jia Rao [mailto:rickenrao@gmail.com]
Sent: Tuesday, November 10, 2009 12:19 PM
To: Dan Magenheimer
Cc: xen-devel@lists.xensource.com
Subject: Re: [Xen-devel] How does the self-ballooning daemon calculate the selftarget?
Hi Dan,
Thanks for the reply.
The XENBALLOON_MINMEM was set to 0 in my case.
I am wondering if the /proc/meminfo is a reliable source for memory utilization of a guest. In my case, the guest stays in idle for several hours, the metrics in /proc/meminfo is seldom changed.
For example, the Committed_AS and Active metrics stay almost the same for several hours.
In earlier kernels, the Active and Inactive metrics are periodically updated by a kernel thread kscand, which seems to has been removed from the 2.6 kernel.
From what I have observed, the meminfo is correctly updated if the memory demand from the guest is increasing. However, once the memory demand drops or be almost zero (idle), the meminfo is not periodically updated. This might be a problem for the self-balloon daemon to deflate the balloon.
Thanks,
Jia
On Tue, Nov 10, 2009 at 12:43 PM, Dan Magenheimer <dan.magenheimer@oracle.com> wrote:
Hi Jia --
There are changes in newer versions of the balloon driver to
ensure that ballooning does not take too much memory away
from the kernel, which would result in kernel crashes.
These changes set a different minimum value depending on
how much memory the kernel originally discovered.
If the self-ballooning scripts run with an "old" balloon
driver and one changes certain parameters
in the scripts, kernel crashes might occur. So the
self-ballooning scripts implement a minimum memory
algorithm similar to the newer balloon driver to
avoid this situation.
Look for XENBALLOON_MINMEM in the xenballoon config file
if you want to change this.
Dan
-----Original Message-----
From: Jia Rao [mailto:rickenrao@gmail.com]
Sent: Tuesday, November 10, 2009 9:23 AM
To: xen-devel@lists.xensource.com
Subject: [Xen-devel] How does the self-ballooning daemon calculate the selftarget?
Hi all,
I am wondering how does the self-ballooning daemon calculate the selftarget for the guest OS.
>From the README of balloon driver, it seems that selftarget is determined by Committed_AS in meminfo.
I did some test on tpcc benchmark. the OS is initially allocated 2048MB of memory, and then I enabled the selfballooning by echo 1 > /proc/xen/balloon.
The configuration of xenballoond.conf is the default except that I enabled self-balloon.
The following is the meminfo
MemTotal: 1939996 kB
MemFree: 1183888 kB
Buffers: 13260 kB
Cached: 396492 kB
SwapCached: 0 kB
Active: 386912 kB
Inactive: 213584 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 1939996 kB
LowFree: 1183888 kB
SwapTotal: 2097136 kB
SwapFree: 2097132 kB
Dirty: 78432 kB
Writeback: 0 kB
AnonPages: 190668 kB
Mapped: 14228 kB
Slab: 53148 kB
PageTables: 4836 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
CommitLimit: 3067132 kB
Committed_AS: 524484 kB
VmallocTotal: 34359738367 kB
VmallocUsed: 1208 kB
VmallocChunk: 34359737159 kB
It seems that the self-balloon driver is reluctant to give up free memory from the guest although the Committed_AS is small. The self-ballooning did changed the selftarget to something like 1.6GB but quickly changed to and fix at 193xxxxKB.
According to the meminfo, we should be able to give up at least 800MB back to the VMM.
FYI: xen 3.3.1, linux 2.6.18.8 in both dom0 and domu.
Any ideas?
Thanks,
Jia
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^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2009-11-11 3:08 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2009-11-10 16:23 How does the self-ballooning daemon calculate the selftarget? Jia Rao
2009-11-10 17:43 ` Dan Magenheimer
2009-11-10 19:18 ` Jia Rao
2009-11-10 20:45 ` Dan Magenheimer
2009-11-11 1:21 ` Jia Rao
2009-11-11 3:08 ` Dan Magenheimer
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