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Got 2.6... diferences?

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I just installed kernel 2.6.0 avaliable on Debian sid repositories (got the kernel image compiled; didn''t compile it myself), and... um... maybe it is a little more responsive, but... err... not quite what i was expecting :/ I have the impression the applications aren''t starting much faster (if at all)... is there a way i can measure/benchmark that? I''ve read people say that "it will feel like you got new hardware"; but, err, i didn''t feel like that... What about you guys? Victor.

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The responsiveness work in 2.6.0 had to do mostly with fairness (having multiple processes get the right amount of CPU time) than with throughput (total efficiency of CPU time usage). 2.4 was great at the latter already but only okay a fairness. 2.6 has a couple schedulers to choose from; the default (the "anticipatory scheduler", if I''m not mistaken) uses a heuristic that is pretty good at figuring out when to give what CPU time and focuses about equally on fairness and throughput. There''s another scheduler with a heuristic that''s all about latency and less focused on throughput (how long it takes something to start once a process decides to do it).

I''m pretty sure you can choose the scheduler at boot time instead of just at compile time, but I''m not sure having not yet tried 2.6 myself (although the Debian Sid packages tempt me too ).

(I''m not a "real" kernel aficionado, so feel free to correct any mistakes in that...)

If X is still niced (the default is "nice -10" in Debian, at least a short while ago), unnice it. The AS (not sure about the other schedulers) really really pays attention to nice values and it will cause X to get too much CPU time. You can change the nice value for X in the file /etc/X11/Xwrapper.config.

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quote:
Original post by Null and Void
The responsiveness work in 2.6.0 had to do mostly with fairness (having multiple processes get the right amount of CPU time) than with throughput (total efficiency of CPU time usage). 2.4 was great at the latter already but only okay a fairness. 2.6 has a couple schedulers to choose from; the default (the "anticipatory scheduler", if I''m not mistaken) uses a heuristic that is pretty good at figuring out when to give what CPU time and focuses about equally on fairness and throughput. There''s another scheduler with a heuristic that''s all about latency and less focused on throughput (how long it takes something to start once a process decides to do it).

I''m pretty sure you can choose the scheduler at boot time instead of just at compile time, but I''m not sure having not yet tried 2.6 myself



Umm... so you think i should try the second scheduler? I''ll search more about it... (hope i can get it on boot time instead of compile time )


quote:

(although the Debian Sid packages tempt me too ).



Hah, talk about temptation!! I actually was going to install the 2.4.22 kernel... but err, i was so tempted... my precisouss... we wantss it!


quote:

If X is still niced (the default is "nice -10" in Debian, at least a short while ago), unnice it. The AS (not sure about the other schedulers) really really pays attention to nice values and it will cause X to get too much CPU time. You can change the nice value for X in the file /etc/X11/Xwrapper.config.



Hmmm.. thanks for that hint! I''ll unnice it.

Victor.

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Oh, by the way...

I understand the new kernel is focused on scalability and all... but, really, i got a bit frustrated because i heard so much talk like "feels like i''ve got a new system!", "feels like it duplicated my processor speed"; and i didn''t feel that...

The thought in my mind was: "either i''m doing something wrong, or these people are using some terribly slow distro... or maybe they''re just trolling."

Victor.

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quote:
Original post by -vic-
I understand the new kernel is focused on scalability and all... but, really, i got a bit frustrated because i heard so much talk like "feels like i''ve got a new system!", "feels like it duplicated my processor speed"; and i didn''t feel that...



Anyone who said that was probably exaggerating. To me, 2.6.0 generally feels a little bit smoother and a little bit more responsive, but its only really noticable under load. Run some stress tests (like the cpuburn package or something) and you might notice it.

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i haven''t noticed many differences apart from this one one issue i used to have (when using 2.4.xx) where xmms would go all crackly/jumpy when doing things like changing tabs in mozilla or starting an application, so i always had to increase its priority to stop the problem. but with 2.6 i don''t have the problem so i guess the improved scheduling is helping.

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