Date: Thu, 09 May 1996 05:11:29 -0700 From: David Greenman <davidg@Root.COM> To: Luigi Rizzo <luigi@labinfo.iet.unipi.it>, s_koyin@eduserv.its.unimelb.EDU.AU, questions@freebsd.org Subject: Re: Disk cache? Message-ID: <199605091211.FAA02000@Root.COM> In-Reply-To: Your message of "Wed, 08 May 1996 23:48:21 PDT." <199605090648.XAA01693@Root.COM>
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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.
I just remembered that we took out the internal usage of cache_max. It's
not used at all in the kernel at the moment.
-DG
David Greenman
Core-team/Principal Architect, The FreeBSD Project
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