Path: utzoo!utgpu!cunews!bnrgate!brtph3!brchh104!brchs1!bnr.ca!rice.edu!sun-spots-request
From: auspex!guy@uunet.uu.net (Guy Harris)
Newsgroups: comp.sys.sun
Subject: Re: What are 'attaches' in vmstat?
Keywords: Miscellaneous
Message-ID: <2312@brchh104.bnr.ca>
Date: 2 Apr 91 15:00:00 GMT
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X-Original-Date: 30 Mar 91 02:27:11 GMT
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>The field in question reports on the vm system's ability to find missing
>pages without having to do any IO.  'at' is the rate (pages/sec) at which
>this is happening.

Yup.

>The attached pages are typically text (code) pages left behind by an
>exited process that was executing the same program.

It's more general in SunOS 4.x; the pages may also have come from a shared
object such as a shared library, or from some other flavor of "mmap()"ped
file, or from a file that was temporarily mapped into kernel virtual
address space for I/O (i.e., the moral equivalent of a buffer cache hit
for a data block is a attach - or, at least, a reclaim; see below). 

From a quick look at the code, it seems to be the case that a "reclaim" is
a page fault resolved by finding the page in memory, while an "attach" is
a "reclaim" where the page was in the free list (i.e., it wasn't mapped
into anybody's address space).