Date: Fri, 30 Jun 2000 12:59:32 -0400 (EDT) From: Kenneth Wayne Culver <culverk@wam.umd.edu> To: Paul Herman <pherman@frenchfries.net> Cc: Harry Newton <harry_newton@telinco.co.uk>, freebsd-questions@FreeBSD.ORG Subject: Re: what is active/inactive memory (was Re: memory leak?) Message-ID: <Pine.GSO.4.21.0006301258120.9424-100000@rac6.wam.umd.edu> In-Reply-To: <Pine.BSF.4.21.0006301757080.224-100000@bagabeedaboo.security.at12.de>
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> On Fri, 30 Jun 2000, Kenneth Wayne Culver wrote: > > > > But what's wired memory ? In some sense the other types > > > (active/inactive/cache/buffer) are probably what one would expect from > > > their names, but wired ... ? > > > > All I know is that's it's memory that can't be freed for one reason or > > another... I think it's where the kernel keeps all it's data structures > > and such... > > Yup, generally, yes. Most of it can't be freed, but there all also > many cases where they do. > > BTW, I should say that both wired and buffer memory are not part of the > active -> inactive -> cache -> free > bucket chain. (See /usr/share/doc/handbook/internals-vm.html) > > Anyway, some things that go into wired memory: > > general kernel stuff: > page table entries, mbufs, NIC IO buffers, DMA buffers > (all contigmalloc() calls) These buffers are generally not > freed up. > > sendfile(2): > pages get wired when waiting to be recieved on the other side > of the socket, so they don't get "ripped out from under" the > calling function. they get freed. > > pipe buffers: > for the same reason as sendfile(2). Try "cat | cat | cat | ..." > and watch wired fly. they get freed. > > execve(2): > a few pages of the executable vnode is mapped into wired. > they get freed. > > I think that's most of it, but there might be a few other cases. (I > double checked before opening my mouth this time, heh heh :) > > -Paul. Heh heh, yeah, I havn't actually looked at that code, I just remembered reading about it in "The design and implementation of 4.4BSD" (I don't know if that's the whole correct name of the book, but I think most people here will know what I'm talking about.) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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