Heavy system load by pagedaemon

Peter Jeremy peterjeremy at optushome.com.au
Fri May 12 07:37:27 UTC 2006

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

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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