From: Andrew Morton <akpm@zip.com.au> To: Linus Torvalds <torvalds@transmeta.com> Subject: Re: Linux 2.4.10-pre11 Date: Mon, 17 Sep 2001 22:48:34 -0700 Cc: Kernel Mailing List <linux-kernel@vger.kernel.org>, Andrea Arcangeli <andrea@suse.de> Linus Torvalds wrote: > > Ok, the big thing here is continued merging, this time with Andrea. > In one test here the VM changes seem fragile, and slower. Dual x86, 512 megs RAM, 512 megs swap. No highmem. The workload is: while true do /usr/src/ext3/tools/usemem 300 done (This just mallocs 300 megs, touches it then exits) in parallel with time /usr/src/ext3/tools/bash-shared-mapping -n 5 -t 3 foo 300000000 on ext2. (bash-shared-mapping is a tool which I wrote for ext3. It's one of the most aggressive VM/MM stress testers around, and has found a number of kernel bugs). On 2.4.9-ac10, the b-s-m run took 294 seconds. On 2.4.10-pre11 it took 330 seconds DESPITE the fact that one of the b-s-m instances was oom-killed quite early in the test. `vmstat' took about thirty seconds to start (this is usual), but was promptly killed, despite having (presumably) a small RSS. Instances of `usemem' were oom-killed quite frequently. In 2.4.9-ac10, nothing was oom-killed. With a gig of VM and a 600 meg working set I don't see why it's necessary to kill processes? Each oom-kill was associated with a 0-order allocation failure. These tools are available at http://www.uow.edu.au/~andrewm/ext3-tools.tar.gz OK, so this was a seriously loony workload. But suddenly, the number of people who understand the Linux VM has gone from maybe 10 down to just one-and-a-bit. A large number of comments have been removed, and a year's worth of discussion has been invalidated. Andrea, it would be most useful if you were to spend some time (say, four hours) commenting the code and telling us how it works. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/