DragonFly kernel List (threaded) for 2005-10
Re: request to nuke gx(4)
:-On [20051002 20:52], Chris Pressey (cpressey@xxxxxxxxxxxxxxx) wrote:
:>Try 'man 4 polling' on any 4.11 machine. There's a mention there.
:Ah. Ok, regardless of the polling 4.11 still kicked 6's butt with polling.
:>btw, ooc, who is "someone" and do they have any plans to measure NetBSD
:A guy on the #FreeBSD channel on Undernet.
:I asked, but I am unsure which NetBSD to ask. 2.0.2 is nice, but 3 has
:Release Candidates out and should be focused on I think.
:Jeroen Ruigrok van der Werven <asmodai(at)wxs.nl> / asmodai / kita no mono
Both FreeBSD's and our DEVICE_POLLING support is based on the hardclock.
I am not really a fan of device polling, but one thing that we could do
that would really differentiate us from FreeBSD and make the device
polling work the way its supposed to would be to separate the polling
frequency from the hardclock.
It turns out that we happen to already have a mechanism, called
SYSTIMERS (which our hardclock uses BTW) which can be used to
independantly schedule the polling frequency and even allow it to be
changed on the fly with a sysctl. It would be considerably more
difficult for FreeBSD to separate their's since they do not have an
equivalent systimer mechanism. I have already separated a number of
periodic functions, such as the scheduler clock, from the original
'hardclock'. I have not separated the networking polling function yet.
Would someone like to take on a mini project to make this fix? Your
starting point would be /usr/src/sys/kern/kern_clock.c. Read the code,
understand how the systimers are used for hardclock(), statclock(),
schedclock(), and so forth, understand how the current DEVICE_POLLING
hooks work (look for 'DEVICE_POLLING' in that source file), and then
do a two-step:
(1) Recode it to use its own systimer.
(2) Add a sysctl to allow the frequency to be changed on the fly.
The polling function you install as the systimer could detect
that the frequency has been changed and reschedule the periodic
systimer with the new frequency.
That would give us slam-bang polling support that would be independant
of our main 'hz'. We would not have to do the (silly thing) FreeBSD
does by continually increasing 'hz' to accomodate particular subsystems.
I think that this is a very doable mini-project for anyone who has
messed with the kernel code a little. There is nothing difficult about