Messages in this thread | | | Date | Tue, 19 Jun 2001 10:41:32 -0700 | From | Larry McVoy <> | Subject | Re: Alan Cox quote? (was: Re: accounting for threads) |
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On Tue, Jun 19, 2001 at 10:36:00AM -0700, Jonathan Lundell wrote: > At 9:09 AM -0700 2001-06-19, Larry McVoy wrote: > >Don't you think it is funny that Sun doesn't publish numbers comparing > >their thread performance to process performance? Sure, you can find > >context switch benchmarks where they have user level switching going on > >but those are a red herring. The real numbers you want are the kernel > >level context switches and those are just as expensive as the process > >context switch numbers. > > Sun (or at least SPARC) is a bit of a special case, though. SPARC's > register-window architecture makes thread-switching (not to mention > recursion) significantly more expensive than on most other > architectures.
Yes, but that misses the point. The point is that you have to do the same work, almost, to switch a kernel thread as a process. You don't have to switch the VM context but that isn't the dominating term. So the fact that Sun has slow[er] context switching and slow[er] thread switching isn't the issue. The issue is that people perceive threads to be cheap but they are not cheap at all. It's the relative cheapness, or lack thereof, when comparing them to processes. -- --- Larry McVoy lm at bitmover.com http://www.bitmover.com/lm - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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