Re: [kvm-devel] [RFC PATCH 1/5] lguest: mmap backing file

Avi Kivity
2008-03-20T15:07:17Z

Anthony Liguori wrote:
> Rusty Russell wrote:
>
>> From: Paul TBBle Hampson <Paul.Hampson-vM6MUUi4OUAAvxtiuMwx3w@public.gmane.org>
>>
>> This creates a file in $HOME/.lguest/ to directly back the RAM and DMA memory
>> mappings created by map_zeroed_pages.
>>
>>
>
> I created a test program recently that measured the latency of a
> reads/writes to an mmap() file in /dev/shm and in a normal filesystem.
> Even after unlinking the underlying file, the write latency was much
> better with a mmap()'d file in /dev/shm.
>

Surely the difference disappears once the pages have been faulted in?

--
error compiling committee.c: too many arguments to function