Date: Fri, 5 Jun 2015 15:44:31 +0300 From: Solar Designer <solar@...nwall.com> To: john-dev@...ts.openwall.com Subject: Re: poor man's fuzzer On Fri, Jun 05, 2015 at 01:50:36PM +0300, Solar Designer wrote: > Another curious detail is that I couldn't get it to use more than ~4 CPU > cores on average, not even with hundreds of simultaneous processes, > until I moved the "run" directory for john to /dev/shm (tmpfs). I guess > I was bumping into some lock congesion in the kernel, possibly e.g. for > atime updates of john and john.conf. (If so, remounting the filesystem > with noatime should probably have helped. I didn't try yet.) So I am > currently running it in /dev/shm/fuzz, which is a bit risky - in case > the system gets rebooted, work will be lost. I should revise the script > to write its log and sample files into a directory different than one it > invokes john from. I've just checked - we already have the filesystem mounted noatime. So the cause of lock contention (or whatever it was) must be different. Maybe the open of john.pot for writing. Alexander
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