Re: /proc/nzombies

From: Walter Hofmann (
Date: Mon Feb 28 2000 - 19:17:07 EST

On Sun, 27 Feb 2000, Ricky Beam wrote:

>"bloat"? It's two lines of code in the process exit path. That adds, what,
>four cpu cylces to process termination? That's not bloat. The price of
>tracking process zombies in the kernel is far, far less than tracking it
>in user land.

It certainly is bloat.

The process exit path is critical--it is called often and every cycle is
important. Take a webserver: It can fork a process per request. Consider
an SMP system: If you write to the same counter repeatedly with all CPUs
you will get cache ping-pong effects which slow you down severely. All
these things have to be considered.

OTOH, counting zombies can be easily done in user space. A monitoring
tool doesn't need to do it more often than, say, once per minute. If it
needs to scan all processes for other purposes as well then counting
zombies is nearly free.


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