Date: Tue, 16 Feb 1999 11:15:44 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: perlsta <bright@cygnus.rush.net> Cc: "John S. Dyson" <dyson@iquest.net>, freebsd-hackers@FreeBSD.ORG Subject: Re: inode / exec_map interlock ? (follow up) Message-ID: <199902161915.LAA37772@apollo.backplane.com> References: <Pine.BSF.3.96.990216140929.10060w-100000@cygnus.rush.net>
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: :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? The new swapper fixes a bunch of things, but the main thing you are probably seeing is the on-the-fly reallocation of swap backing store when swapping out dirty pages and the semi-on-the-fly deallocation of swap backing store when a page is dirtied again. The async I/O swamping problem is so minor it's hardly worth 4 hours of flying felder carp. It took 5 minutes to fix once someone ( other then John ) figured out what the problem was. It should be noted that the original code was documented *solely* as solving a low memory lockup condition. It said absolutely nothing about limiting parallel I/O. Anywhere. In fact, in a large-memory configuration the original code *wouldn't* limit the I/O load because it was scaled to the free page margin rather then scaled to I/O load. What a complete and utter waste of time. -Matt Matthew Dillon <dillon@backplane.com> :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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