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To: des@des.no (Dag-Erling =?iso-8859-1?q?Sm=F8rgrav?=)
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Fri, 01 Aug 2003 11:22:00 +0200."
             <xzpel0568cn.fsf@dwp.des.no> 
Date: Fri, 01 Aug 2003 12:02:00 +0200
Message-ID: <7379.1059732120@critter.freebsd.dk>
cc: Peter Jeremy <PeterJeremy@optushome.com.au>
cc: arch@freebsd.org
Subject: Re: headsup: swap_pager.c 
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In message <xzpel0568cn.fsf@dwp.des.no>, Dag-Erling =?iso-8859-1?q?Sm=F8rgrav?=
 writes:
>"Poul-Henning Kamp" <phk@phk.freebsd.dk> writes:
>> The thing you overlook is that often when things gets paged out, the
>> system is short on memory and therefore more likely to not do anything
>> productive, whereas when things gets paged in, there are a better chance
>> of some other process being able to use the CPU time productively.
>> If we did predictive pageouts like some of the "serious" mainfram OS's
>> this would be less true.
>
>How hard would it be to get the kernel to write the pages "most likely
>to be swapped out" to swap in the idle loop, to save time if / when
>they actually need to be swapped out later?

I don't know :-)

Quite frankly, given the sizes of RAM we see these days, I think that
paging optimizations may be largely a thing of the past.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.