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From: "Benjamin Herrenschmidt" <benh@kernel.crashing.org>
To: "Alan Cox" <alan@lxorguk.ukuu.org.uk>, "Zapp Foster" <zzaappp@yahoo.com>
Cc: "Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>
Subject: Re: Performance improvement inquiry
Date: Sun, 13 Oct 2002 01:58:49 +0200
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>> First question:  Will compiling a kernel with
>> the network module resident (as opposed to a loadable
>> module) make network performance any better?  From
>> the reading, it appears that resident modules are only
>> faster in initialization, not runtime.  I'm new to
>> this, so please correct me if I'm wrong.
>
>Modules are very very fractionally slower than compiled in code due to
>TLB misses

Depends on which arch... on ppc32 (ahem... no bad joke pls ;),
function calls from modules to kernel or between modules has to
go through some "branch islands" as they don't fit within the
scope of a "short" branch PPC insn. So you also get a small
perf. loss there, but I bet it's barely measurable.


Ben.


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