Messages in this thread | | | From | mbs <> | Subject | Re: Periodic clock tick considered harmful (was: Re: HZ, preferably as small as possible) | Date | Thu, 11 Jul 2002 15:19:01 -0400 |
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george,
with the HRT is there any reason to have 10 timer interrupts per process quantum anymore? (10 ms ticks, 100 ms proc quantum)
On Thursday 11 July 2002 15:06, george anzinger wrote: > Ah, but you haven't looked at all that happens on a 1/HZ > tick. The high-res-timers patch does NOT eliminate the 1/HZ > tick. That tick is used to do a LOT of accounting activity > which IMHO is best done by a periodic tick. In particular, > the time slice and execution time management depend on the > periodic tick. As a test we put together a tickless system, > much as suggested above, and put enough stuff in it to see > what the overhead was and how it changed. The conclusion > was that the timer over head increased far beyond the > current overhead as soon as the system load (actually the > number of context switches per second) increased beyond what > a moderately busy system experiences. In other words, the > system was overload prone. The current accounting activity > is flat WRT to context switching which is IMHO just what it > should be. For those who want to know, a patch to put that > test system together is still on the HRT sourceforge site. > > -g > > > OK, so I'm just an ignorant member of the peanut gallery, but > > I'd like to hear a real kernel hacker explain why this isn't > > the way to go. > > > > - Dan
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