On Wednesday 09 February 2005 16:12, Paul Warren wrote: > On Wed, Feb 09, 2005 at 03:20:11PM +0100, Hegedus Gabor wrote: > > 2005-02-09, sze keltezéssel 14:13-kor Paul Warren ezt írta: > > > On Wed, Feb 09, 2005 at 02:59:50PM +0100, Andreas Wohlfeld wrote: > > > > Patch your host with skas and see that the temp files go to a tempfs > > > > mount point (or mount /tmp with tempfs). This will make things a lot > > > > faster. > > > > > > Can someone tell me what the tempfs trick achieves? My understanding > > > was that it prevented the mmapped memory file from being swapped out. > > > Does it do something more than that? > > > > Hi! > > > > It is near to a ramdisk. And you put the uml ramfile to the ramdisk, so > > it is in the real ram couse it is fast. > > Right, but the memory is mmapped to that file. My understanding is that > the memory will only be synced with the disk when either (a) msync (or > munmap) gets called or (b) the kernel has nothing better to do.
Wrong, I guess - the kernel must guarantee some kind of correctness, so things must be flushed... well, the file is deleted, but maybe the optimization for this case (deleted file must not be syncked) was removed away since there are better roads. > I'm assuming that (a) doesn't happen, and I wouldn't expect (b) to > happen if the I/O system is otherwise engaged, so I don't understand > where the performance gain comes from - it should all be in RAM anyway. This part would be correct, but the premise is not. -- Paolo Giarrusso, aka Blaisorblade Linux registered user n. 292729 http://www.user-mode-linux.org/~blaisorblade ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_ide95&alloc_id396&op=click _______________________________________________ User-mode-linux-user mailing list User-mode-linux-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-user
