Messages in this thread | | | From | "Dan Maas" <> | Subject | Re: Low latency for recent kernels | Date | Wed, 23 Jan 2002 22:48:42 -0500 |
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> I'm a little surprised that desktop users do notice significant > benefits with all the latency/preempt patches. If you actually > instrument the kernel's behaviour, the stalls are in fact > quite small and infrequent.
Havoc Pennington, Soeren Sandmann, and I have been investigating causes of UI unresponsiveness in Xfree86/Linux. I would agree that in most situations, on a mostly-idle machine, low-latency/preempt patches should *not* enhance the overall feel of the desktop. (if they do measurably increase responsiveness, then that would suggest inefficiencies in X/the WM/the X client - a definite possibility, of course).
Two situations where I would expect low-latency/preemption to have a positive effect on responsiveness are 1) when the system is under heavy CPU and disk load (e.g. kernel compile); due to the interactive tasks being able to run earlier/more often, and 2) when performing UI operations that depend on tight synchronization between X/the WM/the X client, particularly opaque window resizing. (my theory is that low-latency/preemption results in the CPU switching more rapidly or evenly among these processes, reducing the perceptible "lag" between the client window and its WM frame)
Regards, Dan
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