From: nils t. <use...@ni...> - 2004-11-08 11:30:00
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On Sat, Nov 06, 2004 at 06:08:50AM +0000, Nuno Silva wrote: > Blaisorblade wrote: > >>Maybe having the linux binary in a ramfs will work better? Hmmm, i don't get that: once the UML binary is loaded into host RAM, does it matter how fast the fs is the binary came from? Ok, startup is faster, but also during operation? Is UML reading/loading itself? > >Wise idea! But you forgot the UML "RAM" from $TMPDIR. Now that makes sense to me, too ;) > No i didn't :-) And i advise against it because of the problems that you > point out below (OOM). Anyway, if the data is frequently used it won't > be sent to swap... If you only touch that data once every 5 minutes and > you have some memory pressure you may get a bigger latency. > > If you must have fast-as-it-gets memory access making several UBDs, one > of them very small in ramfs, may be better, YMMV. Ok, depends on scenario. If you have a dedicated host with lots of ram which you are willing to split into seperate fractions it's ok. > ... > > >>You can also do some creative mount --bind, to mount only one ramfs > >>instance, if you have many UMLs running. > > > >Not needed I think - use different names for UML binaries as needed. It > >will pickup a good name for the RAM file. > > I was thinking about chroot environments. And saving some MB by using > the same binary - living in ramfs - to run many UMLs. Yepp. > Regarding double-cacheing you may try NFS NFS may be faster than ubd-devices? Doh! > or directIO (with directIO the > guest can create disk I/O even if it's not needed and ruin the host's > I/O performance). How to do that? <http://www.google.com/search?q=directio+site=user-mode-linux.sourceforge.net> did not show up anything. /nils. -- there is no sig. |