Jean-Christophe Guillain
2005-Aug-10 08:17 UTC
Re: [Xen-users] Maximal RAM reservation for Linux-Dom0
Subhabrata Bhattacharya writes:> Hi, > > I need to know if there is any formula(e) to compute the MAXIMUM > amount of memory I can allocate to host a Domain 0 hosted on > Linux-2.6.11, presuming I don''t intend to run any guest domains on the > host. >If you don''t intend to run any guest domains on the host, I don''t see why you can''t use your whole memory for dom0... But why do you want to use an Xen kernel in this case ? *** Jean-Christophe Guillain jcg@adviseo.fr - (+33) 6 61 52 20 76 http://www.adviseo.fr - http://www.open-sp.fr _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Subhabrata Bhattacharya
2005-Aug-10 08:17 UTC
[Xen-users] Maximal RAM reservation for Linux-Dom0
Hi, I need to know if there is any formula(e) to compute the MAXIMUM amount of memory I can allocate to host a Domain 0 hosted on Linux-2.6.11, presuming I don''t intend to run any guest domains on the host. Consider that I have 512M of RAM available.How much I ''ll be able to exploit with Xen Domain 0. I see that I can''t use the full 507012 kB which is otherwise available to a standard Linux-2.6/2.4. ~$ubh _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Jean-Christophe Guillain
2005-Aug-10 09:09 UTC
Re: [Xen-users] Maximal RAM reservation for Linux-Dom0
Jean-Christophe Guillain writes:> Subhabrata Bhattacharya writes: > >> Hi, >> >> I need to know if there is any formula(e) to compute the MAXIMUM >> amount of memory I can allocate to host a Domain 0 hosted on >> Linux-2.6.11, presuming I don''t intend to run any guest domains on the >> host. >> > > If you don''t intend to run any guest domains on the host, I don''t see why > you can''t use your whole memory for dom0... > But why do you want to use an Xen kernel in this case ? >But I think that it would be interesting to know how to calculate the amount of memory we can''t allocate to any domain when we have several ones running (xen0 + xenUs)... What it depends on ? *** Jean-Christophe Guillain Num. Agrostar : 01 44 29 91 55 jcg@adviseo.fr - 06 61 52 20 76 http://www.adviseo.fr - http://www.open-sp.fr _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Subhabrata Bhattacharya
2005-Aug-10 09:19 UTC
Re: [Xen-users] Maximal RAM reservation for Linux-Dom0
> > If you don''t intend to run any guest domains on the host, I don''t see why you can''t use your whole memory for dom0...I don''t see the reason too but on allocation, I find Xen Domain 0 spitting up cannot allocate enough memory for Domain 0 reservation [something of that sort]> > But why do you want to use an Xen kernel in this case ?Just out of curiosity :)> But I think that it would be interesting to know how to calculate the amount of memory we can''t allocate to any domain when we have several ones running (xen0 + xenUs)... > What it depends on ?Yeah I jibe with this. ~$ubh _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Petersson, Mats
2005-Aug-10 09:34 UTC
RE: [Xen-users] Maximal RAM reservation for Linux-Dom0
Well, the Xen kernel itself will use some memory, and there may be "holes" in the memory too (for example for ISA/BIOS space just under 1MB), so if you''ve got 512MB of memory in your machine, I don''t expect you to be able to give 512MB to the Dom0. I''m not sure how much memory the Xen kernel uses, the code in the kernel itself is about 3-400KB, 24KB of initialized data and 128KB of BSS, so a good half a megabyte, but it will also allocate/reserve some other memory areas, which I''m sure will amount to a fair bit more. For instance, in the mm.c, there''s a single allocation of 4MB for a "mapcache". There are also many small allocations through xmalloc, that build up to some amount of memory usage. How big that is, I can''t really estimate, because it''s too many places to easily and quickly understand what gets run how many times, etc. -- Mats> -----Original Message----- > From: xen-users-bounces@lists.xensource.com > [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of > Subhabrata Bhattacharya > Sent: 10 August 2005 10:20 > To: Jean-Christophe Guillain > Cc: xen-users@lists.xensource.com > Subject: Re: [Xen-users] Maximal RAM reservation for Linux-Dom0 > > > > If you don''t intend to run any guest domains on the host, > I don''t see why you can''t use your whole memory for dom0... > > I don''t see the reason too but on allocation, I find Xen > Domain 0 spitting up cannot allocate enough memory for Domain > 0 reservation [something of that sort] > > > > But why do you want to use an Xen kernel in this case ? > > Just out of curiosity :) > > > > But I think that it would be interesting to know how to > calculate the amount of memory we can''t allocate to any > domain when we have several ones running (xen0 + xenUs)... > > What it depends on ? > > Yeah I jibe with this. > > ~$ubh > > _______________________________________________ > 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