Date: Wed, 08 May 1996 23:48:21 -0700 From: David Greenman <davidg@Root.COM> To: Luigi Rizzo <luigi@labinfo.iet.unipi.it> Cc: s_koyin@eduserv.its.unimelb.EDU.AU, questions@freebsd.org Subject: Re: Disk cache? Message-ID: <199605090648.XAA01693@Root.COM> In-Reply-To: Your message of "Thu, 09 May 1996 08:20:44 %2B0200." <199605090620.IAA01660@labinfo.iet.unipi.it>
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>> All file accesses in FreeBSD are cached and the dynamic cache can grow as
>> large as the amount of RAM in your machine.
>
>Is this really true ? from vm_pageout.c (2.1R) I see the following,
>
> ...
> if (cnt.v_page_count > 1024) {
> cnt.v_cache_max = (cnt.v_free_count - 1024) / 2;
> cnt.v_cache_min = (cnt.v_free_count - 1024) / 8;
> cnt.v_inactive_target = 2*cnt.v_cache_min + 192;
> } else {
> cnt.v_cache_min = 0;
> cnt.v_cache_max = 0;
> cnt.v_inactive_target = cnt.v_free_count / 4;
> }
>
>I assume it means that there is a reserve of pages for other stuff
>than file buffers.
The "cache_max" is only advisor when the system needs to reclaim memory.
There are a few reserved pages that the system must have to avoid deadlocks,
but escentially, any free memory is used for file caching.
-DG
David Greenman
Core-team/Principal Architect, The FreeBSD Project
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