Messages in this thread | | | Date | Thu, 28 Aug 2003 23:58:29 +1000 | From | Nick Piggin <> | Subject | Re: [PATCH]O18.1int |
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Guillaume Chazarain wrote:
>28/08/03 14:34:15, Nick Piggin <piggin@cyberone.com.au> wrote: > >>Guillaume Chazarain wrote: >> >> >>>Hi Con (and linux-kernel), >>> >>>I noticed a regression wrt 2.6.0-test4 and 2.4.22 with this >>>big context-switcher: >>> >>> >>Hi Guillaume, >>If you get the time, would you be able to try my patch? Thanks. >> > >Here are the results for Nick's v8: > >top(1): > > 639 g 30 0 1336 260 1308 R 51.2 0.1 0:03.80 a.out > 638 g 22 0 1336 260 1308 S 47.3 0.1 0:03.39 a.out > >User time (seconds): 0.57 >System time (seconds): 2.72 >Elapsed (wall clock) time (h:mm:ss or m:ss): 0:06.85 >Minor (reclaiming a frame) page faults: 17 > >
Thanks Guillaume, so not very good. Its interesting that there can be such a big difference in performance, but its a very simple app so makes a good test for the specific regression.
In both Con's and my patches, the reader gets a bit more CPU. This might be due to it preempting the writer more often on wakeups, which would lead to more scheduling per work done and a regression.
If this is the case, I'm not sure the behaviour is too undesirable though: its often very important for woken processes to be run quickly. Its not clear that this workload is something we would want to optimize for. Assuming the problem is what I guess.
I will take a look into it further when I get time tomorrow.
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