[LITMUS^RT] RFP: Jumbo Ring Buffers

[Björn Brandenburg]

On Apr 23, 2013, at 6:18 PM, Christopher Kenna <cjk at cs.unc.edu> wrote:

> On Mon, Apr 22, 2013 at 11:55 PM, Björn Brandenburg <bbb at mpi-sws.org> wrote:
>> Thanks a lot for the pointers! How about this function?
>> 
>>        http://lxr.linux.no/linux+v3.0/mm/vmalloc.c#L1680
>> 
>> From the inline documentation, it doesn't sound like there's a limit on the maximum vmalloc() allocation. We don't care whether it is expensive or not; it's a one-time thing anyways.
> 
> I'm no expert, but it seems reasonable. It looks like it does
> something similar (eventually calling map_vm_area, like the other
> function), but also calls kzalloc/kmalloc so that you don't have to
> worry about allocating/tracking your own pages. Glenn might be
> interested in the 'node' parameter, too.

I've coded this up. Please have a look at commit

	https://github.com/LITMUS-RT/litmus-rt/commit/3ffc3fca3bc90d0603454ce3a7f3d3af50d74aab

in branch prop/large-trace-buffers.

I've done some small-scale testing in KVM and it seems to work. Glenn, please give it a try if you get a chance.

Thanks,
Björn

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