Re: Large inlines in include/linux/skbuff.h

From: Eric Dumazet
Date: Thu Apr 22 2004 - 10:38:53 EST

James Morris wrote:

On Thu, 22 Apr 2004, Andi Kleen wrote:

How will these changes impact performance? I asked this last time you posted about inlines and didn't see any response.

I don't think it will be an issue. The optimization guidelines
of AMD and Intel recommend to move functions that generate more than 30-40 instructions out of line. 100 instructions is certainly enough to amortize the call overhead, and you safe some icache too so it may be even faster.

Of course, but it would be good to see some measurements.

- James

It depends a lot of the workload of the machine.

If this a specialized machine, with a small program that mostly uses recv() & send() syscalls, then, inlining functions is a gain, since icache may have a 100% hit ratio. Optimization guidelines are good for the common cases, not every cases.

Eric Dumazet

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