hi. My system has 64GB of Physical RAM. When I boot the system with Xen kernel, I can see only 32GB assigned to dom0. my xm info o/p is; total_memory : 65530 free_memory : 31513 My understanding is when the system is booted with xen kernel, all of the memory should be assigned to dom0. Os is: RH 5.4 64bit. Thanks Paras. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Hi! I don''t really know if this will help, but maybe. http://virtualthreads.blogspot.com/2006/02/understanding-memory-usage-on-linux.html http://it.slashdot.org/article.pl?sid=06/02/06/120210 (they ask/answer alot of questions) You could always post "free -m" I hope this will be, at least, a little helpful. :) Greeting, Simon On Fri, Dec 11, 2009 at 7:23 PM, Paras pradhan <pradhanparas@gmail.com>wrote:> hi. > > My system has 64GB of Physical RAM. When I boot the system with Xen kernel, > I can see only 32GB assigned to dom0. my xm info o/p is; > > total_memory : 65530 > free_memory : 31513 > > My understanding is when the system is booted with xen kernel, all of the > memory should be assigned to dom0. > > Os is: RH 5.4 64bit. > > Thanks > Paras. > > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Fri, 11 Dec 2009, Paras pradhan wrote:> My system has 64GB of Physical RAM. When I boot the system with Xen kernel, > I can see only 32GB assigned to dom0. my xm info o/p is; > > total_memory : 65530 > free_memory : 31513 > > My understanding is when the system is booted with xen kernel, all of the > memory should be assigned to dom0. > > Os is: RH 5.4 64bit.This is a limitation of the Xen kernel; only 32GB will be visible to Dom0. The "missing" 32GB can still be allocated to DomU''s, however. Steve ---------------------------------------------------------------------------- Steve Thompson E-mail: smt AT vgersoft DOT com Voyager Software LLC Web: http://www DOT vgersoft DOT com 39 Smugglers Path VSW Support: support AT vgersoft DOT com Ithaca, NY 14850 "186,300 miles per second: it''s not just a good idea, it''s the law" ---------------------------------------------------------------------------- _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Fri, Dec 11, 2009 at 2:20 PM, Steve Thompson <smt@vgersoft.com> wrote:> On Fri, 11 Dec 2009, Paras pradhan wrote: > > My system has 64GB of Physical RAM. When I boot the system with Xen >> kernel, >> I can see only 32GB assigned to dom0. my xm info o/p is; >> >> total_memory : 65530 >> free_memory : 31513 >> >> My understanding is when the system is booted with xen kernel, all of the >> memory should be assigned to dom0. >> >> Os is: RH 5.4 64bit. >> > > This is a limitation of the Xen kernel; only 32GB will be visible to Dom0. > The "missing" 32GB can still be allocated to DomU''s, however. > >Do I need mem=64G in grub or not ? Thanks Paras. Steve> > ---------------------------------------------------------------------------- > Steve Thompson E-mail: smt AT vgersoft DOT com > Voyager Software LLC Web: http://www DOT vgersoft DOT > com > 39 Smugglers Path VSW Support: support AT vgersoft DOT com > Ithaca, NY 14850 > "186,300 miles per second: it''s not just a good idea, it''s the law" > > ---------------------------------------------------------------------------- >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Sat, Dec 12, 2009 at 3:28 AM, Paras pradhan <pradhanparas@gmail.com> wrote:>>> My system has 64GB of Physical RAM. When I boot the system with Xen >>> kernel, >>> I can see only 32GB assigned to dom0. my xm info o/p is; >>> >>> total_memory : 65530 >>> free_memory : 31513 >>> >>> My understanding is when the system is booted with xen kernel, all of the >>> memory should be assigned to dom0.No, it shouldn''t. In fact, it''s actually best practice to LIMIT the ammount of dom0 memory from the start.>>> >>> Os is: RH 5.4 64bit. >> >> This is a limitation of the Xen kernel; only 32GB will be visible to Dom0. >> The "missing" 32GB can still be allocated to DomU''s, however.AFAIK it''s a "limitation" of RHEL''s kernel-xen. They did it for a very good reason though: providing a usable dom0 system on servers with >32GB memory. You could probably override that behavior with some kernel command line options, but it''s not recommended.> Do I need mem=64G in grub or not ?If you plan to have some domUs running on it, you can leave it as it is. domU will be able to use the 32GB currently not in use by dom0. In fact, domUs can also use some memory currently used by dom0, so if already have an idea how much memory domUs will be using in total, you can (later) limit dom0 memory usage to start with less memory (I usually set it to somewhere between 500M - 1G). -- Fajar _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Hi, On Fri, Dec 11, 2009 at 4:16 PM, Fajar A. Nugraha <fajar@fajar.net> wrote:> On Sat, Dec 12, 2009 at 3:28 AM, Paras pradhan <pradhanparas@gmail.com> > wrote: > >>> My system has 64GB of Physical RAM. When I boot the system with Xen > >>> kernel, > >>> I can see only 32GB assigned to dom0. my xm info o/p is; > >>> > >>> total_memory : 65530 > >>> free_memory : 31513 > >>> > >>> My understanding is when the system is booted with xen kernel, all of > the > >>> memory should be assigned to dom0. > > No, it shouldn''t. In fact, it''s actually best practice to LIMIT the > ammount of dom0 memory from the start. > > >>> > >>> Os is: RH 5.4 64bit. > >> > >> This is a limitation of the Xen kernel; only 32GB will be visible to > Dom0. > >> The "missing" 32GB can still be allocated to DomU''s, however. > > AFAIK it''s a "limitation" of RHEL''s kernel-xen. They did it for a very > good reason though: providing a usable dom0 system on servers with >> 32GB memory. >For a dom0 to be usable and stable, i guess 32 GB of memory is not needed. Around 1GB should be enough(?) and this 1 GB is set using dom0_mem=1Gb param? correct me if i am wrong.> > You could probably override that behavior with some kernel command > line options, but it''s not recommended. > > > Do I need mem=64G in grub or not ? > > If you plan to have some domUs running on it, you can leave it as it > is. domU will be able to use the 32GB currently not in use by dom0. > > In fact, domUs can also use some memory currently used by dom0, so if > already have an idea how much memory domUs will be using in total, you > can (later) limit dom0 memory usage to start with less memory (I > usually set it to somewhere between 500M - 1G). >So is it still true that domU can use memory more than 32GB whereas it is showing up only 32G? I will having around 20 virtual machines and each will use 1 to 2 CPU and 2 GB of RAM. So, i need some suggestions here. Thanks ! Paras.> > -- > Fajar >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Sat, Dec 12, 2009 at 5:57 AM, Paras pradhan <pradhanparas@gmail.com> wrote:>> AFAIK it''s a "limitation" of RHEL''s kernel-xen. They did it for a very >> good reason though: providing a usable dom0 system on servers with >>> 32GB memory. > > For a dom0 to be usable and stable, i guess 32 GB of memory is not needed.Actually, the case is, if you have 64GB memory, and all of them is made available initially to dom0, and later it was balloon down (for domU) to (for example) 2GB, you''ll be having problems. To prevent that, the initial dom0 memory is limited by default to be 32GB max.> Around 1GB should be enough(?)If dom0 does not run any additional services, yes, it should be more than enough.> and this 1 GB is set using dom0_mem=1Gbkernel /xen.gz dom0_mem=512M> So is it still true that domU can use memory more than 32GB whereas it is > showing up only 32G? I will having around 20 virtual machines and each will > use 1 to 2 CPU and 2 GB of RAM.Yes. If domU in total uses about 40GB, they will use the 32GB unused plus another 8GB taken from dom0. -- Fajar _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Thanks Fajar for the info.
I set dom0_mem to 1G and here is my several outputs .
xm li:
Name ID Mem(MiB) VCPUs State Time(s)
Domain-0 0 1024 16 r----- 116.6
free -m:
total used free shared buffers cached
Mem: 1024 582 441 0 25 296
-/+ buffers/cache: 260 763
Swap: 32765 0 32765
xm info:
total_memory : 65530
free_memory : 63257
I believe I am doing good now !
Paras.
On Fri, Dec 11, 2009 at 8:39 PM, Fajar A. Nugraha <fajar@fajar.net> wrote:
> On Sat, Dec 12, 2009 at 5:57 AM, Paras pradhan
<pradhanparas@gmail.com>
> wrote:
> >> AFAIK it''s a "limitation" of RHEL''s
kernel-xen. They did it for a very
> >> good reason though: providing a usable dom0 system on servers with
>> >> 32GB memory.
> >
> > For a dom0 to be usable and stable, i guess 32 GB of memory is not
> needed.
>
> Actually, the case is, if you have 64GB memory, and all of them is
> made available initially to dom0, and later it was balloon down (for
> domU) to (for example) 2GB, you''ll be having problems. To prevent
> that, the initial dom0 memory is limited by default to be 32GB max.
>
> > Around 1GB should be enough(?)
>
> If dom0 does not run any additional services, yes, it should be more
> than enough.
>
> > and this 1 GB is set using dom0_mem=1Gb
>
> kernel /xen.gz dom0_mem=512M
>
> > So is it still true that domU can use memory more than 32GB whereas it
is
> > showing up only 32G? I will having around 20 virtual machines and each
> will
> > use 1 to 2 CPU and 2 GB of RAM.
>
> Yes. If domU in total uses about 40GB, they will use the 32GB unused
> plus another 8GB taken from dom0.
>
> --
> Fajar
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users
>
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