Date: Sun, 29 Jul 2001 13:07:14 -0700 From: Terry Lambert <tlambert2@mindspring.com> To: Kazutaka YOKOTA <yokota@zodiac.mech.utsunomiya-u.ac.jp> Cc: freebsd-current@freebsd.org Subject: Re: Death sentence to KLD screen savers? Comments? Message-ID: <3B646CF2.F5E332A9@mindspring.com> References: <200107241207.VAA14339@zodiac.mech.utsunomiya-u.ac.jp> <3B5E7DB3.97656D3C@mindspring.com> <200107260729.QAA25125@zodiac.mech.utsunomiya-u.ac.jp>
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Kazutaka YOKOTA wrote: > >> I propose to have user-land screen savers instead of KLD > >> screen savers. > > > >[ ... "performance degradation" ... ] > > > >[ ... "file access" ... ] > > > >I don't see either of these as being compelling arguments > >in favor of a user space implementation; I guess this means > >you want to do file access in your screen saver(s). > > Both points/complaints/requests have been raised several times in our > mailing lists in the past. (Sorry, I don't keep copies.) I didn't say they weren't arguments, merely that I did not find them compelling. This looks to me like change for the sake of change. > Some people don't like cputime eaten up by the screen saver in the > kernel... The simple answer for this is to run in a kproc, and set the priority to "idle", so it only runs when there is nothing else to run. Actually, running in user space adds two problems: 1) Performance degradation as a result of protection domain crossing which does not exist in the current implementation 2) Inability to disable the screen saver in, for example, a "panic" situation, where there is no opportunity to return to user space and have the screen put back into a known good state. This is analogous to the problem we have diagnosing kernel panics while X11 is running on the console: only the user space program can undo what it has done, and we can not run the user space program. > Some peopel want to write "interesting" screen savers... Now we see the real reason for this... 8^). > >Now if you could run Windows screen saver modules, you > >might have a good argument for change, above and beyond > >"change for the sake of change". > > Personally I am not interested in fancy screen savers :-) But, just want > to keep things tidy and keep the system running smoothly. By moving > much of the screen saver support from the console driver to the > user-land... The problem here is that only the video driver knows what it knows; short of converting FreeBSD's console over to something like "GGI", you will have a hard time moving *everything* to userland. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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