On Thu, Oct 16, 2014 at 04:23:36PM +0200, Rohan Garg wrote: > > A consistent kernel and performance expectations across Ubuntu is also > > worthwhile. I don't want someone screw up database/VM/etc. workloads > > benchmarks simply > > because they happen to have kubuntu-desktop installed or left around
> Are we honestly optimizing for benchmarks now? I'd rather optimize for > a good user experience, which in the case of Kubuntu requires the use > of CFQ. I couldn't care less about > random-news-site-running-random-benchmarks. I don't think Dimitri actually meant "benchmarks" here. I think "workload performance" is the real question. There seems to be a grave misunderstanding that the scheduler change was working around a bug in Unity (cf. https://blogs.kde.org/2014/10/15/ubuntus-linux-scheduler-or-why-baloo-might-be-slowing-your-system-1404). This was *never* about a bug in Unity; Unity simply has a feature that provides visual indication to the user when an application is unresponsive, and with CFQ on HDD, many users found their apps were unresponsive quite a lot. Removing the visual indicator wouldn't improve app responsiveness for these users; the configurations in question would still have been sluggish under CFQ. That baloo is not well-modeled by the performance testing that was done before, is clear. But changing the scheduler for the whole system is a very big hammer, not to be used lightly. We've agreed that the kubuntu-settings change is acceptable for an SRU in spite of reservations; but it's in everyone's interest - including that of Kubuntu users who run VMs on their desktop, or other workloads that suffer under CFQ - to find a long-term solution that doesn't require such a heavy-handed change. If someone were to demonstrate that CFQ is actually better than deadline with recent kernels across all relevant workloads, then it's a no-brainer to switch back. But without that, something like the proposed cgroup handling is probably in order. -- Steve Langasek Give me a lever long enough and a Free OS Debian Developer to set it on, and I can move the world. Ubuntu Developer http://www.debian.org/ [email protected] [email protected]
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