Re: maximum memory size allocated by _xmalloc

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 11/07/12 10:13, Chulmin Kim wrote:
> Hi all, 
>
> I'm currently inserting my own code to adjust the several existing memory
> ballooning works. 
>
> To accomplish it, I manage some kind of statistics in Xen memory area. 
>
> Using _xmalloc, I've allocated certain size of memory chunk for the data
> structure. ( I varied it from 10kb to 24 MB.)
>
> When the size is equal to 24 MB, xen won't boot anymore.  (stuck during the
> xmalloc, according to my debugging. _xmalloc returns NULL.)
> There was no problem when the size is below 12MB.
>
> Is there any limitation such as max memory size for _xmalloc? 
>
> I suspected xen heap size, but, it is no longer adjustable. Right? 
>
> I hope somebody can give me a clue.  Thanks.

_xmalloc will first try to use the size pools for allocation, and
failing that, try to allocate full pages.

As it is returning NULL, this probably means you no longer have 24MB of
free contiguous RAM to allocate.

~Andrew

>
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-- 
Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer
T: +44 (0)1223 225 900, http://www.citrix.com