Re: another thing I noticed (scheduling?)

[Hiten Pandya <hmp@xxxxxxxxxxxxx>]

Matthew Dillon wrote:
> :Hi,
> :    Just another thing I noticed last night while using DragonflyBSD.
> :Interactivity suffers immensely when the cpu is at 100%. I was compiling java
> :1.4.1 from ports last night, and trying to use the gimp to resize some pictures
> :at the same time. It took 15 seconds to simply load a jpg file (normally it's
> :almost instant, even under heavy cpu load). Also, during the compile, just
> :starting the gimp, or any other moderately large program would just stall until
> :I ctrl-z'ed the build to pause it. The progress bar when gimp loads would
> :literally just stop moving until I paused the build.
> :
> :This looks to me like a scheduling problem, but I can't remember reading
> :anything on the website saying that you changed the scheduler. Anyway, this is
> :just to let people know what I saw when using DragonflyBSD. I realize that it's
> :very much a development system, so I'm not (yet) expecting it to be anywhere
> :near perfect, but telling people what I'm seeing should help fix the problems
> :right? Anyway, if there's any other info anyone needs, let me know.
> :
> :Ken
>
>     I wouldn't worry about this too much.  There are certainly going to be
>     scheduler priority issues due to a number of temporary mechanisms
>     currently being used in the code (such as the way critical sections are
>     employed in the token code), but the userland scheduler is basically
>     the same as what was in 4.x so the issues are mainly just going to be
>     cockpit trouble.  e.g. I'm probably missing a userland preemption 
>     somewhere which is giving cpu bound processes too much cpu.

	Another thing that might help is to turn on profiling:

	# cd /sys/i386/conf/ && config -g -p TINDERBOX
	# cd /sys/compile/TINDERBOX && make depend && make

	... load profile enabled kernel ...

	# kgmon -b
	# try the compile until CPU reaches 100%
	# kgmon -h
	# gprof /<path-to-profile-kernel> gmon.out

	And then send the resulting file from gprof.  It might
	help in dealing with the problem.

	Regards,

--
Hiten Pandya
hmp@xxxxxxxxxxxxx