Date: Sun, 30 Jul 2006 01:50:36 +0200 From: Michal Mertl <mime@traveller.cz> To: Paul Allen <nospam@ugcs.caltech.edu> Cc: Peter Jeremy <peterjeremy@optushome.com.au>, freebsd-current@freebsd.org, Brian Candler <B.Candler@pobox.com> Subject: Re: vmstat's entries type Message-ID: <1154217036.23616.28.camel@genius.i.cz> In-Reply-To: <1154216319.23616.23.camel@genius.i.cz> References: <200607251254.k6PCsBef092737@lurza.secnetix.de> <200607271058.13055.jhb@freebsd.org> <20060728121525.GA44917@uk.tiscali.com> <200607280928.36573.jhb@freebsd.org> <20060728134701.GA45273@uk.tiscali.com> <20060728210154.GC748@turion.vk2pj.dyndns.org> <1154189612.1565.10.camel@genius.i.cz> <20060729205655.GE748@turion.vk2pj.dyndns.org> <20060729211530.GA50342@uk.tiscali.com> <1154212340.3609.18.camel@genius.i.cz> <20060729230214.GI12597@groat.ugcs.caltech.edu> <1154216319.23616.23.camel@genius.i.cz>
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Michal Mertl wrote: > Paul Allen wrote: > > Surely all you need to do is a cheap crit_enter,crit_exit > > while updating the 64-bit per cpu counters. and on > > a 64-bit arch you skip the crit_enter,crit_exit. > > Critical_enter/exit seem to be quite lightweight (single > read/modify/write of a variable). One more question. Why do you say that crit_* can be avoided on 64-bit arch? If the reason was that "increment of a 64 bit number is one operation there" it probably is not true - as somebody already stated, some instruction sets don't allow atomic increment of a memory location. Michal
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