Date: Fri, 12 May 2006 17:17:11 +1000 From: Peter Jeremy <peterjeremy@optushome.com.au> To: Iasen Kostov <tbyte@otel.net> Cc: FreeBSD Hackers <freebsd-hackers@freebsd.org> Subject: Re: Heavy system load by pagedaemon Message-ID: <20060512071711.GA714@turion.vk2pj.dyndns.org> In-Reply-To: <1147361590.33341.19.camel@DraGoN.OTEL.net> References: <1147264089.51661.10.camel@DraGoN.OTEL.net> <1147264379.51661.14.camel@DraGoN.OTEL.net> <1147265038.51661.19.camel@DraGoN.OTEL.net> <1147361590.33341.19.camel@DraGoN.OTEL.net>
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On Thu, 2006-May-11 18:33:10 +0300, Iasen Kostov wrote: > And another odd thing (to me atleast): > >#:> vmstat -s | grep "daemon\|fault" > 0 page daemon wakeups > 0 pages examined by the page daemon > 4992608 copy-on-write faults > 29021 copy-on-write optimized faults > 75167 intransit blocking page faults > 66956262 total VM faults taken > 0 pages freed by daemon > >Acording to vmstat pagedaemon has never been awake. 'page daemon wakeups' counts the number of times that the pagedaemon is woken up due to a page shortage. It does not include the 5-sec wakeups. How about posting a complete 'vmstat -s'. A look at the code suggests that vm_pageout_page_stats() thinks there's a page shortage (since that's the only piece of code that will actually do anything if page daemon wakeups is zero). >Kamal R. Prasad suggested that "Belady's anomaly" might occur. If it's >true or possible what could be done about this ? "Belady's anomaly" can only occur if paging really happens. -- Peter Jeremy
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