Messages in this thread | | | Date | Tue, 4 Feb 2014 10:14:05 +0100 | From | Ingo Molnar <> | Subject | Re: [RFC PATCH 3/3] idle: store the idle state index in the struct rq |
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* Peter Zijlstra <peterz@infradead.org> wrote:
> [...] > > The reason Ingo took it out was that these measured numbers would > slightly vary from boot to boot making it hard to compare > performance numbers across boots. > > There's something to be said for either case I suppose.
Yeah, so we could put the parameters back by measuring it in user-space via a nice utility in tools/, and by matching it to relevant hardware signatures (CPU type and cache sizes), plus doing some defaults for when we don't have any signature... possibly based on a fuzzy search to find the 'closest' system in the table of constants.
That would stabilize the boot-to-boot figures while still keeping most of the system specific-ness, in a maintainable fashion.
The downside is that we'd have to continuously maintain a table of all this info, with new entries added when new CPUs are introduced on the market. That's an upside too, btw.
Thanks,
Ingo
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