Date: Sat, 06 Jul 1996 08:57:42 +0100 From: "Gary Palmer" <gpalmer@FreeBSD.ORG> To: Tom Bartol <bartol@salk.edu> Cc: hackers@FreeBSD.ORG Subject: Re: Shared Memory Questions Message-ID: <21008.836639862@palmer.demon.co.uk> In-Reply-To: Your message of "Sat, 06 Jul 1996 00:22:25 PDT." <Pine.SUN.3.93.960705234755.17590A-100000@helmholtz>
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Tom Bartol wrote in message ID <Pine.SUN.3.93.960705234755.17590A-100000@helmholtz>: > segs in gimp from time to time, but I'd like to be able to choose and tune > the shared memory parameters at will, and to do so with config options if > possible. Or better yet, why can't the kernel just allow these > resources to grow without bound until RAM and VM are exhausted? If you read param.c: /* * Values in support of System V compatible shared memory. XXX */ #ifdef SYSVSHM #ifndef SHMMAX #define SHMMAX (SHMMAXPGS*NBPG) #endif [etc, etc] In other words, if you put an option in your kernel configuration file saying: options "SHMMAX=1024" (or whatever), then that'll over-ride the value calculated in param.c. This does allow you to specify the values at config-time, rather than hard-coding them. In answer to your second question, in /sys/i386/i386/machdep.c, kernel memory is pre-allocated during boot time to handle the SYS V IPC primitives (they need contiguous memory?). I'm also betting that the user-land applications would be mightily confused by dynamic memory areas. > So, the bottom line is this -- can any of you give some advice on how to > tune shared memory in FreeBSD? Are these numbers meant to be hard coded > and un-tweekable? Can it be done at all? I really know next to nothing > about shared memory and any help you can give would be greatly > appreciated (virtual beers etc...) :) Sorry, can't help with the virtual beers. I don't drink :-) Gary -- Gary Palmer FreeBSD Core Team Member FreeBSD: Turning PC's into workstations. See http://www.FreeBSD.ORG/ for info
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