On Sat, 2012-11-03 at 20:41 +0200, Konstantin Belousov wrote: > On Sat, Nov 03, 2012 at 12:38:39PM -0600, Ian Lepore wrote: > > 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. > > No, I propose to add a switch to turn on/off the mlockall() call. > I have no opinion on the default value of the suggested switch.
In a patch I submitted along with the PR, I added code to query the vm.swap_enabled sysctl and only call mlockall() when swapping is enabled. Nobody yet has said anything about what seems to me to be the real problem here: jemalloc grabs 8MB at a time even if you only need to malloc a few bytes, and there appears to be no way to control that behavior. Or maybe there's a knob in there that didn't jump out at me on a quick glance through the header files. -- Ian _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "[email protected]"
