Hello, I am running a functional Xen 4.0 platform. The objective is the project I am currently running is to replace 4 VMWare ESX by 4 Xen 4.0 hypervisors. I have been able to reproduce all the core VMWare features in Xen (but better of course =D) except memory overcommitment. I know this feature has been included since Xen 3.3 but I have found almost no information about it. When I try to start a domain with more RAM then is available on the server I get the following message : *VmError: I need 1433600 KiB, but dom0_min_mem is 200704 and shrinking to 200704 KiB would leave only 1348320 KiB free.* Well I know it doesn''t have enough RAM, that''s the whole point. Do I need to enable something specific somewhere ? I am using the Jeremy''s 2.6.31 kernel (thank you whoever you may be !). Thank you in advance for your help, Antoine _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Does anyone have any pointers concerning memory overcommitment ? Thank you in advance for your help, Antoine On Wed, Apr 21, 2010 at 10:23 PM, Antoine Benkemoun < antoine.benkemoun@gmail.com> wrote:> Hello, > > I am running a functional Xen 4.0 platform. The objective is the project I > am currently running is to replace 4 VMWare ESX by 4 Xen 4.0 hypervisors. I > have been able to reproduce all the core VMWare features in Xen (but better > of course =D) except memory overcommitment. > > I know this feature has been included since Xen 3.3 but I have found almost > no information about it. > > When I try to start a domain with more RAM then is available on the server > I get the following message : > > *VmError: I need 1433600 KiB, but dom0_min_mem is 200704 and shrinking to > 200704 KiB would leave only 1348320 KiB free.* > > Well I know it doesn''t have enough RAM, that''s the whole point. Do I need > to enable something specific somewhere ? I am using the Jeremy''s 2.6.31 > kernel (thank you whoever you may be !). > > Thank you in advance for your help, > > Antoine >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
I guess you should learn the Transcendent Memory (http://oss.*oracle* .com/projects/*tmem*/) from Oracle... Am I right? Cheers! Thiago On 26 April 2010 05:54, Antoine Benkemoun <antoine.benkemoun@gmail.com>wrote:> Does anyone have any pointers concerning memory overcommitment ? > > > Thank you in advance for your help, > > Antoine > > On Wed, Apr 21, 2010 at 10:23 PM, Antoine Benkemoun < > antoine.benkemoun@gmail.com> wrote: > >> Hello, >> >> I am running a functional Xen 4.0 platform. The objective is the project I >> am currently running is to replace 4 VMWare ESX by 4 Xen 4.0 hypervisors. I >> have been able to reproduce all the core VMWare features in Xen (but better >> of course =D) except memory overcommitment. >> >> I know this feature has been included since Xen 3.3 but I have found >> almost no information about it. >> >> When I try to start a domain with more RAM then is available on the server >> I get the following message : >> >> *VmError: I need 1433600 KiB, but dom0_min_mem is 200704 and shrinking to >> 200704 KiB would leave only 1348320 KiB free.* >> >> Well I know it doesn''t have enough RAM, that''s the whole point. Do I need >> to enable something specific somewhere ? I am using the Jeremy''s 2.6.31 >> kernel (thank you whoever you may be !). >> >> Thank you in advance for your help, >> >> Antoine >> > > > _______________________________________________ > 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
2010/4/27 Martinx - ジェА璽爛 <thiagocmartinsc@gmail.com>:> I guess you should learn the Transcendent Memory > (http://oss.oracle.com/projects/tmem/) from Oracle... > Am I right? > Cheers! > Thiago > > On 26 April 2010 05:54, Antoine Benkemoun <antoine.benkemoun@gmail.com> > wrote: >> >> Does anyone have any pointers concerning memory overcommitment ? >> >> Thank you in advance for your help, >> >> Antoine >> >> On Wed, Apr 21, 2010 at 10:23 PM, Antoine Benkemoun >> <antoine.benkemoun@gmail.com> wrote: >>> >>> Hello, >>> >>> I am running a functional Xen 4.0 platform. The objective is the project >>> I am currently running is to replace 4 VMWare ESX by 4 Xen 4.0 hypervisors. >>> I have been able to reproduce all the core VMWare features in Xen (but >>> better of course =D) except memory overcommitment. >>> >>> I know this feature has been included since Xen 3.3 but I have found >>> almost no information about it. >>> >>> When I try to start a domain with more RAM then is available on the >>> server I get the following message : >>> >>> VmError: I need 1433600 KiB, but dom0_min_mem is 200704 and shrinking to >>> 200704 KiB would leave only 1348320 KiB free. >>> >>> Well I know it doesn''t have enough RAM, that''s the whole point. Do I need >>> to enable something specific somewhere ? I am using the Jeremy''s 2.6.31 >>> kernel (thank you whoever you may be !). >>> >>> Thank you in advance for your help, >>> >>> AntoineYou may want to read about the balloon driver in xen. http://wiki.xensource.com/xenwiki/XenFaq#head-ff507535c38a3191053dad83d8d68d19c5482e70 Miguel _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Hello, Thank you for your help. I have seen the mentionned information. I am understanding that the initial memory allocation given to a domain is the absolute minimum it can use. After that, you can increase it on overcommitment pools. Is this even right ? I am surprised to find so little information about such a great and useful feature. This usually means I am missing something big... Antoine 2010/4/27 Miguel <miguelrvs@gmail.com>> 2010/4/27 Martinx - ジェА璽爛 <thiagocmartinsc@gmail.com>: > > I guess you should learn the Transcendent Memory > > (http://oss.oracle.com/projects/tmem/) from Oracle... > > Am I right? > > Cheers! > > Thiago > > > > On 26 April 2010 05:54, Antoine Benkemoun <antoine.benkemoun@gmail.com> > > wrote: > >> > >> Does anyone have any pointers concerning memory overcommitment ? > >> > >> Thank you in advance for your help, > >> > >> Antoine > >> > >> On Wed, Apr 21, 2010 at 10:23 PM, Antoine Benkemoun > >> <antoine.benkemoun@gmail.com> wrote: > >>> > >>> Hello, > >>> > >>> I am running a functional Xen 4.0 platform. The objective is the > project > >>> I am currently running is to replace 4 VMWare ESX by 4 Xen 4.0 > hypervisors. > >>> I have been able to reproduce all the core VMWare features in Xen (but > >>> better of course =D) except memory overcommitment. > >>> > >>> I know this feature has been included since Xen 3.3 but I have found > >>> almost no information about it. > >>> > >>> When I try to start a domain with more RAM then is available on the > >>> server I get the following message : > >>> > >>> VmError: I need 1433600 KiB, but dom0_min_mem is 200704 and shrinking > to > >>> 200704 KiB would leave only 1348320 KiB free. > >>> > >>> Well I know it doesn''t have enough RAM, that''s the whole point. Do I > need > >>> to enable something specific somewhere ? I am using the Jeremy''s 2.6.31 > >>> kernel (thank you whoever you may be !). > >>> > >>> Thank you in advance for your help, > >>> > >>> Antoine > > You may want to read about the balloon driver in xen. > > http://wiki.xensource.com/xenwiki/XenFaq#head-ff507535c38a3191053dad83d8d68d19c5482e70 > > Miguel > > _______________________________________________ > 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 Wed, Apr 21, 2010 at 10:23:39PM +0200, Antoine Benkemoun wrote:> Hello, > > I am running a functional Xen 4.0 platform. The objective is the project I > am currently running is to replace 4 VMWare ESX by 4 Xen 4.0 hypervisors. > I have been able to reproduce all the core VMWare features in Xen (but > better of course =D) except memory overcommitment. >What do you exactly mean with memory overcommitment here? Xen supports memory ballooning, but it has never really supported memory overcommit, by design. Memory in Xen guests is guaranteed to be real memory, so the guests will perform well using it. If you need some virtual/overcommitted memory just add more swap to the guest.> I know this feature has been included since Xen 3.3 but I have found > almost no information about it. >I don''t think Xen 3.3 has any kind of memory overcommit.> When I try to start a domain with more RAM then is available on the server > I get the following message : > > VmError: I need 1433600 KiB, but dom0_min_mem is 200704 and shrinking to > 200704 KiB would leave only 1348320 KiB free. >See: http://wiki.xensource.com/xenwiki/XenBestPractices You should use dom0_mem= parameter for xen.gz to dedicate a fixed amount of memory for dom0.> Well I know it doesn''t have enough RAM, that''s the whole point. Do I need > to enable something specific somewhere ? I am using the Jeremy''s 2.6.31 > kernel (thank you whoever you may be !). > > Thank you in advance for your help, >Xen 4.0 actually added some forms of memory overcommit, tmem and hvm guest memory page sharing (de-duplication). See: http://wiki.xensource.com/xenwiki/Xen4.0 -- Pasi _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users