Date: Tue, 1 Aug 2006 05:12:06 +1000 From: Peter Jeremy <peterjeremy@optushome.com.au> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-current@freebsd.org Subject: Re: vmstat's entries type Message-ID: <20060731191206.GE749@turion.vk2pj.dyndns.org> In-Reply-To: <200607311437.57273.jhb@freebsd.org> References: <200607251254.k6PCsBef092737@lurza.secnetix.de> <20060728134701.GA45273@uk.tiscali.com> <20060728210154.GC748@turion.vk2pj.dyndns.org> <200607311437.57273.jhb@freebsd.org>
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On Mon, 2006-Jul-31 14:37:56 -0400, John Baldwin wrote:
>On Friday 28 July 2006 17:01, Peter Jeremy wrote:
>> This approach still requires the reader to loop with something like
>> do {
>> a.lo = counter.lo;
>> a.hi = counter.hi;
>> b.lo = counter.lo;
>> b.hi = counter.hi;
>> } while (a.hi != b.hi || a.lo > b.lo);
>> to ensure that the reader doesn't read the middle of an update.
>
>Yes, but the idea here is that these stats are written to far more often than
>read, so it's ok to pessimize the read case.
We are in violent agreement here. My point was that the reader has
to be aware of this requirement.
--
Peter Jeremy
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