Too much attention on large systems? [LWN.net]

Paolo Ciarrocchi recently posted an article giving some benchmark results on his laptop; these results generally show that 2.5.33 performs a little more slowly than the 2.4 kernels. Given that much of the work in 2.5 has been oriented around performance, what is happening here? Daniel Phillips summarized things as follows:

I suspect the overall performance loss on the laptop has more to do with several months of focussing exclusively on the needs of 4-way and higher smp machines.

The fear that large systems performance work would slow things down on the hardware that most of us actually use has been present for years. Could it be that the big iron is finally taking over the kernel?

The answer, for now, is probably "no." 2.5 development efforts have indeed emphasized large systems performance so far. The small-systems performance has not been impaired so much as simply passed over for now. As Andrew Morton put it:

It's on the larger machines where 2.4 has problems. Fixing them up makes the kernel broader, more general purpose. We're seeing 50-100% gains in some areas there. Giving away a few percent on smaller machines at this stage is OK. But yup, we need to go and get that back later

Small-systems tuning, of course, is work that can mostly happen after next month's feature freeze. Expect some serious efforts in that direction - small and embedded systems, after all, are a huge part of the Linux user base. It wouldn't do to leave them out in the cold.

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