Re: 15000+ processes -- poor performance ?!

[David Lang]

Ok, I wasn't sure of the cause, but I've seen this as far back as 2.2 I
had a machine trying to run 2000 processes under 2.2 and 2.4.0 (after
upping the 2.2 kernel limit) and top would cost me ~40% throughput on the
machine (while claiming it was useing ~5% of the CPU)

David Lang

 On Wed, 18 Dec 2002, William Lee Irwin III wrote:

> Date: Wed, 18 Dec 2002 17:25:49 -0800
> From: William Lee Irwin III <[e-mail]>
> To: David Lang <[e-mail]>
> Cc: Till Immanuel Patzschke <[e-mail]>,
>      lse-tech <[e-mail]>,
>      "[e-mail]" <[e-mail]>
> Subject: Re: 15000+ processes -- poor performance ?!
>
> On Wed, Dec 18, 2002 at 05:12:41PM -0800, David Lang wrote:
> > also top is very inefficant with large numbers of processes. use vmstat
> > or cat out the files in /proc to get the info more efficiantly (it won't
> > get you per process info, but it son't cause the interferance with your
> > desired load that top gives you.)
>
> It's mostly just the fact top(1) doesn't scan /proc/ incrementally and
> that proc_pid_readdir() is quadratic in the number of tasks.
>
>
> Bill
>