Date: Tue, 16 Feb 1999 14:20:45 -0500 (EST) From: perlsta <bright@cygnus.rush.net> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: "John S. Dyson" <dyson@iquest.net>, freebsd-hackers@FreeBSD.ORG Subject: Re: inode / exec_map interlock ? (follow up) Message-ID: <Pine.BSF.3.96.990216140929.10060w-100000@cygnus.rush.net> In-Reply-To: <199902161808.KAA37094@apollo.backplane.com>
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On Tue, 16 Feb 1999, Matthew Dillon wrote: > :John S. Dyson said: > :> Matthew Dillon said: > :> > > :> > The ORIGINAL VM CODE. Do I need to repeat that? The *ORIGINAL* VM CODE > :> > does not have one single line of source to prevent excessive queueing > :> > of I/O for pageout ops. > :> > > :> You are wrong. Please look at the code. I will point the code out to you > :> if you want, but I suspect that you don't want to know. > :> > :Please refer to the message that I sent to you on 10 Jan 99 for some more > :information in that arena. Apparently you didn't listen -- and what I > :said describes essentially what the nastier (but correctly working) > :swap pager does. > : > :I even explained to you in terms of "clogging" the I/O subsystem and blindly > :freeing pages. That is a *very* real problem, and the old swap pager largely > :stopped that from happening. Maybe this isn't the gretest time to jump in with a question, but i'm interested in the working of the former and current systems. I've noticed that the 'old' swapper or system seemed to leave a LOT of swap still used en it wasn't trully needed. The new system seems to reclaim these regeons as soon as they are swapped in. I've noticed the new swapper is a bit more 'peppy' but i'm concerned that it is dooing what John says. What's the deal here? Matt, even though your swapper lists pages as 'free' does it actually keep them around for reuse? What happens when a page is READ faulted in, is the backing swap kept allocated to save on IO later? One other thing, I has some trouble getting to sleep last night and decided to venture into src/sys/vm, the comments are VERY helpful. The kind of documentation going on here will really help people get into systems programming, it is MUCH appreciated. -Alfred To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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