Date: Sat, 03 Nov 2012 12:38:39 -0600 From: Ian Lepore <freebsd@damnhippie.dyndns.org> To: freebsd-hackers@freebsd.org, freebsd-embedded@freebsd.org Subject: watchdogd, jemalloc, and mlockall Message-ID: <1351967919.1120.102.camel@revolution.hippie.lan>
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In an attempt to un-hijack the thread about memory usage increase between 6.4 and 9.x, I'm starting a new thread here related to my recent discovery that watchdogd uses a lot more memory since it began using mlockall(2). I tried statically linking watchdogd and it made a small difference in RSS, presumably because it doesn't wire down all of libc and libm. VSZ RSS 10236 10164 Dynamic 8624 8636 Static Those numbers are from ps -u on an arm platform. I just updated the PR (bin/173332) with some procstat -v output comparing with/without mlockall(). It appears that the bulk of the new RSS bloat comes from jemalloc allocating vmspace in 8MB chunks. With mlockall(MCL_FUTURE) in effect that leads to wiring 8MB to satisfy what probably amounts to a few hundred bytes of malloc'd memory. It would probably also be a good idea to remove the floating point from watchdogd to avoid wiring all of libm. The floating point is used just to turn the timeout-in-seconds into a power-of-two-nanoseconds value. There's probably a reasonably efficient way to do that without calling log(), considering that it only happens once at program startup. -- Ian
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