Date: Wed, 11 Aug 1999 12:02:48 -0700 From: John-Mark Gurney <gurney_j@efn.org> To: Jeff Aitken <jaitken@aitken.com> Cc: des@flood.ping.uio.no, dillon@apollo.backplane.com, freebsd-security@FreeBSD.ORG Subject: Re: 4 Swap partitions limit (was Re: RE: Little question (offtopic)) Message-ID: <19990811120248.23702@hydrogen.fircrest.net> In-Reply-To: <199908111851.OAA21052@eagle.aitken.com>; from Jeff Aitken on Wed, Aug 11, 1999 at 02:51:03PM -0400 References: <14257.50009.162402.381699@trooper.velocet.ca> <199908111851.OAA21052@eagle.aitken.com>
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Jeff Aitken scribbled this message on Aug 11: > David Gilbert writes: > > One curious aspect of FreeBSD that I havn't explained to my own > > satisfaction is why it appears to consume more swap than linux. > > From: http://www.freebsd.org/FAQ/FAQ235.html#238 > > 12.1. FreeBSD uses far more swap space than Linux. Why? > > FreeBSD only appears to use more swap than Linux. In actual fact, it > does not. The main difference between FreeBSD and Linux in this > regard is that > FreeBSD will proactively move entirely idle, unused pages of main > memory into swap in order to make more main memory available for > active use. > Linux tends to only move pages to swap as a last resort. The > perceived heavier use of swap is balanced by the more efficient use > of main memory. > > Note that while FreeBSD is proactive in this regard, it does not > arbitrarily decide to swap pages when the system is truely idle. > Thus you will not find > your system all paged out when you get up in the morning after > leaving it idle overnight. this should also be updated to say that it doesn't dump and zero the pages... it just puts them on disk so if there is an immediate need for a large chunk of memory that it can dump pages that have been swapped out w/o having to wait for them to be swapped out.. so the more use of swap actually helps performance because you can get large chunks of memory faster... -- John-Mark Gurney Voice: +1 541 684 8449 Cu Networking P.O. Box 5693, 97405 "The soul contains in itself the event that shall presently befall it. The event is only the actualizing of its thought." -- Ralph Waldo Emerson To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-security" in the body of the message
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