RE: [Xen-devel] Xen runs out of memory!

["Jayaraman, Bhaskar" <Bhaskar.Jayaraman@xxxxxxx>]

Keir, I'm using a 64 bit unstable version of Xen. 4 Core single socket CPU with 
8GB memory and Dom0 is using around 2.5GB. What do I do to lift heap size 
restrictions? 

The only other domain that comes up is my HVM which squeezes Xen out of memory.

Do you think I can increase contiguous pages by increasing the value of 
MAX_ORDER, which is right now defined as 
#define MAX_ORDER 20 /* 2^20 contiguous pages */

Which is a hell of a lot of pages and all I'm asking for are 1536 contiguous 
ones.

However when I checked in xen/common/page_alloc.c I see the following: -
typedef struct list_head heap_by_zone_and_order_t[NR_ZONES][MAX_ORDER+1]

Should this have been: -
typedef struct list_head 
heap_by_zone_and_order_t[NR_ZONES][(int)pow(2,MAX_ORDER * +1)]

??


Bhaskar.

-----Original Message-----
From: Keir Fraser [mailto:keir.fraser@xxxxxxxxxxxxx] 
Sent: Thursday, March 12, 2009 4:03 PM
To: Jayaraman, Bhaskar; xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-devel] Xen runs out of memory!

Are you running a 64-bit hypervisor? You want to do that, and with latest
xen-unstable, to lift Xen-heap size restrictions. Beyond that, make sure
that other domains (especially dom0) are not using all the memory. Restrict
dom0¹s memory usage by using the dom0_mem= option on Xen¹s command line, for
example.

 -- Keir

On 12/03/2009 10:20, "Jayaraman, Bhaskar" <Bhaskar.Jayaraman@xxxxxxx> wrote:

> Hi all, I¹m trying to increase max grant table frames from the current 32
> pages to a user defined value. I¹m basically trying to map an entire domain
> into another so I have say a Linux HVM with 3GB memory and I¹m trying to map
> the whole domain into another domain with 4GB memory.
>  
> So I set the max grant frames to 1536 (needed to map 3GB of memory into any
> domain), but when I setup the grant table for that many frames Xen is only
> able to setup 1427 grant table frames at the most and Xen fails after this in
> alloc_heap_pages.
>  
> I¹m also not able to bring up any other HVM after this, i.e. xen has no memory
> for any other domains, which makes me wonder if anyone has tested the maximum
> domUs that can be brought up on Xen (255 right?).
>  
> Is there anyway I can make this memory allocation succeed? i.e. by increasing
> Xen memory or some other means? (Xen in HVM uses 64MB)
>  



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