Messages in this thread | | | Subject | Re: [2.6.24.x] UML select()/poll() oversleeping reproducibly | From | Nix <> | Date | Mon, 17 Mar 2008 21:08:16 +0000 |
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On 17 Mar 2008, Jeff Dike verbalised:
> Below is the same patch with another kluge, which cuts down the > requested sleep by 10% in hopes of getting the actual sleep closer to > what's wanted.
Eeuuuuw. :)
> This is unusable in anything resembling mainline, but I'd like to see > how your various systems react to it. I'm getting very close to the > sleeps I asked for (with slight undersleeping, which is a bug).
OK.
Tests on host with clocksource pit:
bash-3.2# bin/select-sleep 5 Slept for 5 seconds. bash-3.2# bin/select-sleep 10 Slept for 11 seconds. bash-3.2# bin/select-sleep 30 Slept for 31 seconds. bash-3.2# bin/select-sleep 60 Slept for 61 seconds.
... so much better than the 4x error without this patch.
Tests on host with clocksource tsc:
bash-3.2# bin/select-sleep 5 Slept for 5 seconds. bash-3.2# bin/select-sleep 10 Slept for 10 seconds. bash-3.2# bin/select-sleep 30 Slept for 30 seconds. bash-3.2# bin/select-sleep 60 Slept for 61 seconds.
Distinctly better than without this patch.
(Am I the only person who finds it strange that (some) clocksource hackers are arguing about accuracy problems in the ppm range while we're glad to get an error of `only' single seconds per minute out of it? Maybe next year we can invent the `pendulum' clocksource :) )
-- `The rest is a tale of post and counter-post.' --- Ian Rawlings describes USENET
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