Re: [RFC v2] Support volatile range for anon vma

[Arun Sharma]

On 11/5/12 5:49 PM, Minchan Kim wrote:

> > Also, memory allocators have a second motivation in using madvise: to
> > create virtually contiguous regions of memory from a fragmented address
> > space, without increasing the RSS.
>
> I don't get it. How do we create contiguos region by madvise?
> Just out of curiosity.
> Could you elaborate that use case? :)

By using a new anonymous map and faulting pages in.

The fragmented virtual memory is released via MADV_DONTNEED and if the 
malloc/free activity on the system is dominated by one process, chances 
are that the newly faulted in page is the one released by the same 
process :)

The net effect is that physical pages within a single address space are 
rearranged so larger allocations can be satisfied.

 -Arun
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/