RDSL and ignoring feedback
Posted Jul 26, 2007 13:35 UTC (Thu) by corbet
In reply to: RDSL and ignoring feedback
Parent article: Still waiting for swap prefetch
Indeed. Imho Corbet should've mentioned this properly - Con did get
negative comments, but those where entirely silly. Complaining about the
fairness of a fair scheduler???
That's just the sort of approach which created trouble for SD/RSDL. If people see regressions with their workloads, stamping a "100% certified fair!" label on it will not make them feel better about it. You have to address these problems; if you are unwilling to do so, your code will not make it into the kernel.
CFS is also a "fair" scheduler, but it has not drawn the same sort of complaints - though it will be interesting to see what happens as the testing community gets larger. As I understand it, the CFS brand of "fairness" takes a longer-term view, allowing tasks to get their "fair" share even if they sleep from time to time. That helps to prevent the sort of regressions seen with SD.
The real key, though, is what happens when things go wrong. There will certainly be people reporting scheduler issues over the 2.6.23 cycle. Ingo and the other CFS hackers could certainly dismiss them as "entirely silly," seeing as the scheduler is "completely fair," after all. But they won't do that. Instead, they will do their best to understand and solve the problems. That is why CFS is in the kernel, and SD is not.
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