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From
SubjectRe: sed not working on /proc files
Date
In muc.lists.linux-kernel, you wrote:
>Hi,
>
>On Mon, 26 Apr 1999 17:17:10 -0400, Chip Salzenberg
><chip@perlsupport.com> said:
>
>> Hm. Would it be a Bad Thing for mmap to fail on /proc files that
>> don't report true sizes?
>
>We don't need to support mmap for /proc at all. In fact, according to
>mmap semantics, we can't: there is no permanent memory reserved for
>/proc at all.

mmap'ed /proc would be a nice way to implement efficient access to
some of the system statistics for programs that read them often (the
read seems to be a bottle neck for some programs, like wmcpu)

Implementing it would be a nightmare though: e.g. how do you guarantee
consistency of data between the "data updaters" in the kernel and
the user processes?

A better strategy is most likely to move more and more of the
information into read-only sysctls. Then they can be still accessed
via /proc/sys/*, and program needing more efficient access can
use sysctl(2).

This also would map nicely onto a "Linux-MIB" for remote network
control.

A generic compatibility layer between sysctl.c and fs/proc/array.c
would be probably rather easy and a nice 2.3 project for someone (so
that most of the old /proc stuff would just be a simple table driven
wrapper around the sysctl data structures)

-Andi

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