linux-kernel - dynamic linking files slow fork down significantly

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Date:	Fri, 2 Mar 2007 16:53:41 -0800 (PST)
From:	David Lang <dlang@...italinsight.com>
To:	linux-kernel@...r.kernel.org
Subject: dynamic linking files slow fork down significantly

I have a fork-heavy workload (a proxy that forks per connection, I know it's not 
the most efficiant design) and I discovered a 2x performance difference between 
a static and dynamicly linked version of the same program (2200 connections/sec 
vs 4700 connections/sec)

I know that there is overhead on program startup, but didn't expect to find it 
on a fork with no exec. If I has been asked I would have guessed that the static 
version would have been slower due to the need to mark more memory as COW.

what is it that costs so much with dynamic libraries on a fork/clone?

according to strace, the clone call that's being made is
clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, 
child_tidptr=0xb7c92c08)

David Lang
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