Date: Thu, 03 Mar 2005 14:55:38 +0800 From: David Xu <davidxu@freebsd.org> To: David Schultz <das@freebsd.org> Cc: John Baldwin <jhb@freebsd.org> Subject: Re: cvs commit: src/sys/kern kern_sig.c Message-ID: <4226B4EA.40308@freebsd.org> In-Reply-To: <20050303064206.GA14434@VARK.MIT.EDU> References: <200503021343.j22DhpQ3075008@repoman.freebsd.org> <200503020915.28512.jhb@FreeBSD.org> <4226446B.7020406@freebsd.org> <20050303033115.GA13174@VARK.MIT.EDU> <42269DB0.6070107@freebsd.org> <20050303052902.GA14011@VARK.MIT.EDU> <4226A46B.2090704@freebsd.org> <20050303060357.GA14180@VARK.MIT.EDU> <20050303001403.W811@odysseus.silby.com> <20050303064206.GA14434@VARK.MIT.EDU>
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David Schultz wrote: >On Thu, Mar 03, 2005, Mike Silbersack wrote: > > >>On Thu, 3 Mar 2005, David Schultz wrote: >> >> >> >>>Of course, there's another possible solution which is to remove >>>the swapping code entirely. That would certainly simplify things, >>>but it would also make FreeBSD degrade less gracefully under load. >>> >>> >>I don't think that would be a big loss; by the time you're doing a lot of >>process swapping, you're pretty screwed. >> >>A process has to be swapped back in in order for it to be killed, right? >>We might be better off without swapping, in that case. >> >> > >Yeah, with 16K kernel stacks, you'd have to swap a lot of threads >to make a big difference in the amount of wired memory in the >system. KSE helps with this, because processes with thousands of >user threads don't have thousands of kernel threads. > > > This only happens at comparative idle time, if the process is a heavy I/O bound process, this does not help. >Another thing that swapping does, though, is prevent some >processes from running for a while when the system is under load, >thereby reducing contention for resources and allowing the other >processes to get things done. If people decide to go this way, it >might be a good idea to keep the second feature. It costs very >little in terms of complexity because no actual swapping is done. >But who knows? Maybe nobody cares about this, either... > > > I would like to not swap out kernel stack, it allows me to write some speedy code, this is my personal favorit. :=)
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