On Sun, 6 Mar 2005, Krisztian PIFKO wrote: > could someone please tell me how much memory an uml consumes > if the temp dir for the unlinked temp files is on tmpfs? > > for example does a 64M uml use 2*64 megs of ram this way?
My UML is configured with 120 MB simulated RAM. Host and guest have kernel 2.6.8, with SKAS on the host. I made the UML hog the CPU plus do a lot of I/O and then ran "top", which says: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 13191 jimc 17 0 123m 92m 122m S 89.7 36.9 0:56.64 linux 13196 jimc 15 0 392 80 392 T 6.3 0.0 0:13.30 linux After all that, "df" on the tmpfs filesystem with the image file indicates that it occupies 96.4 MB. So definitely the memory is not allocated twice. My understanding is that tmpfs allocates an I/O page for the data just as if it had been read/written to disc, but it wasn't. Then the user (UML) maps (not copies) that page into its own address space. I imagine that the 31 MB difference between the virtual address space and the resident set (nearly equal to the image size) is occupied by 2.95 MB of UML kernel and the program text of various system daemons and their shared libraries, mapped from the host's file that's attached to /dev/ubda. James F. Carter Voice 310 825 2897 FAX 310 206 6673 UCLA-Mathnet; 6115 MSA; 405 Hilgard Ave.; Los Angeles, CA, USA 90095-1555 Email: [EMAIL PROTECTED] http://www.math.ucla.edu/~jimc (q.v. for PGP key) ------------------------------------------------------- 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_id=6595&alloc_id=14396&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