Hello List,
i have 8GB RAM on a 64Bit Hardware in a 32Bit Debian Installation.
proxy01:~# free -m
total used free shared buffers cached
Mem: 7575 922 6652 0 374 92
-/+ buffers/cache: 456 7118
Swap: 511 0 511
proxy01:~# xm list
Name ID Mem VCPUs State
Time(s)
Domain-0 0 7575 4 r-----
239312.6
fw 15 2048 2 -b----
207029.1
fw2 20 512 2 r-----
6276.0
ssl 17 512 1 -b---- 25.2
proxy01:~# file /bin/bash
/bin/bash: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV),
dynamically linked (uses shared libs), for GNU/Linux 2.6.8, stripped
Question: Does this make sense? Can i assign almost all my 8GB to my
guests? Or will this cause problems?
Thanks,
Mario
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On Wed, 2013-07-03 at 10:41 +0200, ml ml wrote:> Question: Does this make sense? Can i assign almost all my 8GB to my > guests? Or will this cause problems?Assigning up to, say, 7GB to guests to ballooning dom0 down to 1GB ought to be fine. Below that you run the risk of dom0 running short of memory because some data structures are sized at boot to fit the 8GB size and cannot be shrunk when ballooning. The point at which this can happen varies though so you could experiment, e.g. you might be fine going down to 512M in dom0. If you run into trouble then you could use the dom0_mem= hypervisor option to reduce the maximum amount of RAM dom0 can see, which would cause those static datastructures to be proportionately smaller. Of course this means that you cannot easily use that RAM for dom0 when no domains are running, so whether this is appropriate depends on your usecase. Ian.
Hello Lan, thanks for your reply. I am aware that i need to leave enough ram for my Dom0. I was just wondering if the concept all together works: Dom0 = 32Bit but 8GB Ram (in 32Bit can only handle up to 4GB?!) Cheers, Mario On Wed, Jul 3, 2013 at 10:54 AM, Ian Campbell <Ian.Campbell@citrix.com>wrote:> On Wed, 2013-07-03 at 10:41 +0200, ml ml wrote: > > > Question: Does this make sense? Can i assign almost all my 8GB to my > > guests? Or will this cause problems? > > Assigning up to, say, 7GB to guests to ballooning dom0 down to 1GB ought > to be fine. Below that you run the risk of dom0 running short of memory > because some data structures are sized at boot to fit the 8GB size and > cannot be shrunk when ballooning. The point at which this can happen > varies though so you could experiment, e.g. you might be fine going down > to 512M in dom0. > > If you run into trouble then you could use the dom0_mem= hypervisor > option to reduce the maximum amount of RAM dom0 can see, which would > cause those static datastructures to be proportionately smaller. Of > course this means that you cannot easily use that RAM for dom0 when no > domains are running, so whether this is appropriate depends on your > usecase. > > Ian. > > > >_______________________________________________ Xen-users mailing list Xen-users@lists.xen.org http://lists.xen.org/xen-users
On Wed, 2013-07-03 at 11:13 +0200, ml ml wrote:> Hello Lan, > > thanks for your reply. I am aware that i need to leave enough ram for > my Dom0. I was just wondering if the concept all together works: > > Dom0 = 32Bit but 8GB Ram (in 32Bit can only handle up to 4GB?!)A 32-bit PAE kernel (which is required to run on Xen 32-bit anyway) can handle up to ~16GB of RAM in total, although obviously any one process can only have up to 4GB. Ian.> > > Cheers, > Mario > > > > On Wed, Jul 3, 2013 at 10:54 AM, Ian Campbell > <Ian.Campbell@citrix.com> wrote: > On Wed, 2013-07-03 at 10:41 +0200, ml ml wrote: > > > Question: Does this make sense? Can i assign almost all my > 8GB to my > > guests? Or will this cause problems? > > > Assigning up to, say, 7GB to guests to ballooning dom0 down to > 1GB ought > to be fine. Below that you run the risk of dom0 running short > of memory > because some data structures are sized at boot to fit the 8GB > size and > cannot be shrunk when ballooning. The point at which this can > happen > varies though so you could experiment, e.g. you might be fine > going down > to 512M in dom0. > > If you run into trouble then you could use the dom0_mem> hypervisor > option to reduce the maximum amount of RAM dom0 can see, which > would > cause those static datastructures to be proportionately > smaller. Of > course this means that you cannot easily use that RAM for dom0 > when no > domains are running, so whether this is appropriate depends on > your > usecase. > > Ian. > > > > > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xen.org > http://lists.xen.org/xen-users
Excellent! Thank you!!! On Wed, Jul 3, 2013 at 11:22 AM, Ian Campbell <Ian.Campbell@citrix.com>wrote:> On Wed, 2013-07-03 at 11:13 +0200, ml ml wrote: > > Hello Lan, > > > > thanks for your reply. I am aware that i need to leave enough ram for > > my Dom0. I was just wondering if the concept all together works: > > > > Dom0 = 32Bit but 8GB Ram (in 32Bit can only handle up to 4GB?!) > > A 32-bit PAE kernel (which is required to run on Xen 32-bit anyway) can > handle up to ~16GB of RAM in total, although obviously any one process > can only have up to 4GB. > > Ian. > > > > > > > Cheers, > > Mario > > > > > > > > On Wed, Jul 3, 2013 at 10:54 AM, Ian Campbell > > <Ian.Campbell@citrix.com> wrote: > > On Wed, 2013-07-03 at 10:41 +0200, ml ml wrote: > > > > > Question: Does this make sense? Can i assign almost all my > > 8GB to my > > > guests? Or will this cause problems? > > > > > > Assigning up to, say, 7GB to guests to ballooning dom0 down to > > 1GB ought > > to be fine. Below that you run the risk of dom0 running short > > of memory > > because some data structures are sized at boot to fit the 8GB > > size and > > cannot be shrunk when ballooning. The point at which this can > > happen > > varies though so you could experiment, e.g. you might be fine > > going down > > to 512M in dom0. > > > > If you run into trouble then you could use the dom0_mem> > hypervisor > > option to reduce the maximum amount of RAM dom0 can see, which > > would > > cause those static datastructures to be proportionately > > smaller. Of > > course this means that you cannot easily use that RAM for dom0 > > when no > > domains are running, so whether this is appropriate depends on > > your > > usecase. > > > > Ian. > > > > > > > > > > > > _______________________________________________ > > Xen-users mailing list > > Xen-users@lists.xen.org > > http://lists.xen.org/xen-users > > >_______________________________________________ Xen-users mailing list Xen-users@lists.xen.org http://lists.xen.org/xen-users