topic Re: swapper process in Operating System - HP-UX

swapper process

Marc Bohnert — Tue, 27 Jun 2006 15:37:21 GMT

Running HPUX 11.11

Using glance I noticed that the swapper process is consistently one of the top processes in generating disk IO. I am seeing 200-300 I/Os per second over the 5 second sample. At the same time there is no page outs or deactivations. There is ample memory, 12GB. I am seeing Oracle log writer process also generating large amounts of I/O which makes sense but not swapper. From what I've read swapper is only responsible for process deactivations. What's up?

Thanks,

Marc Bohnert

Re: swapper process

A. Clay Stephenson — Tue, 27 Jun 2006 16:12:59 GMT

I would guess that you are running dynamic buffer cache and that max_dbc_pct is set fairly high.

Re: swapper process

A. Clay Stephenson — Tue, 27 Jun 2006 16:15:12 GMT

Ooops, I'm stupid that should be dbc_max_pct; I never run that dynamic stuff so I don't need to know them tunables no how.

Re: swapper process

Marc Bohnert — Wed, 28 Jun 2006 07:30:40 GMT

What does swapper have to do with dynamic buffer cache. Does it control shrinking the cache to dbc_min_pct

Re: swapper process

James R. Ferguson — Wed, 28 Jun 2006 08:58:58 GMT

Hi Marc:

The *syncer* daemon manages the dynamic buffer cache, *but* if the buffer cache is large, leading to memory pressure, the *swapper* daemon may see in increased workload as it operates to deactivate processes and the *pager* (vhand) daemon moves pages to swapspace.

Regards!

...JRF...

Re: swapper process

Marc Bohnert — Wed, 28 Jun 2006 09:02:36 GMT

There is no indication of memory pressure. page outs and deactivations are zero.