Hello, I finally found it out: On my Debian system the path for this memory file is /dev/shm, so I mounted this to the chroot jail of my UML and performance significantly improved (~30x). For large blocks (dd if=... - you remember) it is still significantly slower than on the host, but 25% of the performance of the host is way better than <1%. I think I can live with that...
With kind regards, Torsten Lang -- Torsten Lang -----Ursprüngliche Nachricht----- Von: Torsten Lang [mailto:[EMAIL PROTECTED] Gesendet: Mittwoch, 22. Oktober 2008 08:59 An: user-mode-linux-user@lists.sourceforge.net Cc: 'Anselm Lingnau' Betreff: Re: [uml-user] 2nd try: Problem with UML on Kernel 2.6.26 (very low performance, heavy disk activity IMHO on memory allocations) Hi, please can you tell me a bit more about this subject? Actually, I'm using some Debian packages from the old c't server 1 and modified the start/stop/init.d scripts. The UMLs themselves run in a chroot environment. But as far as I can see there are no special RAM disks set up or so. As far as I remeber when reading documentation I didn't find anything about such a behaviour... BTW, I wrote some small test programs that simply allocate RAM, or allocate RAM and write to /dev/null, allocate RAM and read from /dev/zero and finally do a copy. The operation that triggers the disk activity is reading from /dev/zero - this takes several seconds for a 128M read request. I've done some more experiments and found that the performance for this dd breaks down at block sizes of about 32MB and above. With kind regards, Torsten Lang -- Torsten Lang -----Ursprüngliche Nachricht----- Von: Anselm Lingnau [mailto:[EMAIL PROTECTED] Gesendet: Dienstag, 21. Oktober 2008 16:30 An: user-mode-linux-user@lists.sourceforge.net Betreff: Re: [uml-user] 2nd try: Problem with UML on Kernel 2.6.26 (very low performance, heavy disk activity IMHO on memory allocations) Torsten Lang wrote: > To make it short: Everything works stable but way too slow. The effect > is that in my opinion every larger memory allocation leads to heavy > disk activity. Do you use a tmpfs (RAM disk) for the file UML uses to store your virtual machine's RAM? Anselm -- Anselm Lingnau, Friedberg, Germany ..................... [EMAIL PROTECTED] Women and cats will do as they please, and men and dogs should relax and get used to the idea. -- Robert A. Heinlein ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ User-mode-linux-user mailing list User-mode-linux-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-user ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ User-mode-linux-user mailing list User-mode-linux-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-user ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ User-mode-linux-user mailing list User-mode-linux-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-user
