> -----Original Message----- > From: Paolo Giarrusso [mailto:[EMAIL PROTECTED] > Sent: Thursday, December 16, 2004 2:05 PM > To: [EMAIL PROTECTED] > Cc: Sala, Roger > Subject: Re: [uml-user] RE: User-mode-linux-user digest, Vol 1 #1829 - > 11 msgs > > > [...] > > > In an attempt to test this, I rebooted and repeated all the > above steps, > > except I lied to the uml and told it that it had three > times more memory > > than the $TMPDIR partition. > > > > `linux ubd0=/dev/hda6 ubd1=/dev/hda5 mem=180000K > > eth0=tuntap,,,192.168.0.254` > > > > `top` on the guest now happily reported 153240K available > at the start. > > > > Everything went down similarly when I ran the `find`; the > host sucked down > > its available memory very quickly -- although this time it > did eventually > > swap. The guest gobbled up its available memory also, but > at a slower > > rate. I expected it to crash after it used 60000K, and then > 120000K, but it > > used up just about all its reported "available" memory and > still kept > > running for a while. It never used any of its own swap. > > > Continuously running `df /mnt/ram6` showed the free memory > eventually go > > right to zero, shortly before the guest segfaulted. > Checked the value without the cache size?
Thank you for pointing out the buffers/cache component of free/used memory, but after reading up on it a bit, its my impression that, although this memory is readily usable if needed, it is still memory that has been written to -- and thus should show as used when running `df` on the host's ram disk/$TMPDIR. > > My impression is that the guest is not using its > "dedicated" ram or swap > > very efficiently. > 2.6.9 kernels, on any arch, often go OOM instead of swapping > (discussed > somewhere on http://lwn.net/Kernel). Thanks again. I turned up the swappiness on the guest kernel to 100 and it indeed swapped. > > > It also seems to be able to get into the host's ram > > somehow. > Hmm, quite unlikely... I'm inclined to agree with you. I think a more likely explanation for what I'm seeing is that `top` is reporting all the memory that has been malloc'd, whereas `df` on the ram disk is reflecting only the pages that have actually generated a page fault and been allocated. I'm also suprised how much host memory usage the guests generate. When I start a uml, the host usage jumps by about 40M, which is just about all given back as soon as the uml is halted. If I start a uml and run the `find`, the host's free memory is quiclky depleted -- in this case about 130M. Again when the uml is halted, just about all the 130M is freed. This is above and beyond the 65M ramdisk that is carved out before the guest is started, and which is not given back when the guest is halted. This, along with the "Host Memory Usage" uml page leads me to believe that creating a ramdisk (for the sake of partitioning resources) isn't buying me that much since the host is (copying?) all the guest's pages anyway. > -- > 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://productguide.itmanagersjournal.com/ _______________________________________________ User-mode-linux-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/user-mode-linux-user
