watchdogd, jemalloc, and mlockall

[Konstantin Belousov]

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.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 196 bytes
Desc: not available
URL: <http://lists.freebsd.org/pipermail/freebsd-embedded/attachments/20121103/81a82663/attachment.sig>