From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [kvm-devel] [RFC PATCH 1/5] lguest: mmap backing file Date: Thu, 20 Mar 2008 17:07:17 +0200 Message-ID: <47E27DA5.6090703@qumranet.com> References: <200803201659.14344.rusty@rustcorp.com.au> <200803201705.44422.rusty@rustcorp.com.au> <47E26EE1.5030706@codemonkey.ws> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Cc: kvm-devel , lguest , virtualization-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Anthony Liguori Return-path: In-Reply-To: <47E26EE1.5030706-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: lguest-bounces+glkvl-lguest=m.gmane.org-mnsaURCQ41sdnm+yROfE0A@public.gmane.org Errors-To: lguest-bounces+glkvl-lguest=m.gmane.org-mnsaURCQ41sdnm+yROfE0A@public.gmane.org List-Id: kvm.vger.kernel.org Anthony Liguori wrote: > Rusty Russell wrote: > >> From: Paul TBBle Hampson >> >> 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