Messages in this thread | | | Subject | Re: O(1) scheduler gives big boost to tbench 192 | From | Robert Love <> | Date | 07 May 2002 16:39:34 -0700 |
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On Tue, 2002-05-07 at 15:43, Mike Kravetz wrote:
> I'm not doing any prefetches in the code (if that is what you are > talking about). The code just moves the pipe reader to the same > CPU as the pipe writer (which is about to block). Certainly, the > pipe reader could take advantage of any data written by the writer > still being in the cache.
Hm, interesting. When Ingo removed the sync variants of wake_up he did it believing the load balancer would handle the case. Apparently, at least in this case, that assumption was wrong.
I agree with your earlier statement, though - this benchmark may be a case where it shows up negatively but in general the balancing is preferred. I can think of plenty of workloads where that is the case. I also wonder if over time the load balancer would end up putting the tasks on the same CPU. That is something the quick pipe benchmark would not show.
> I'm not sure if 'synchronous' is still being passed all the way > down to try_to_wake_up in your tree (since it was removed in 2.5). > This is based off a back port of O(1) to 2.4.18 that Robert Love > did. The rest of try_to_wake_up (the normal/common path) remains > the same.
In 2.5 nor the 2.4 backport I did (what is in -ac) I don't think the sync flag is being passed down since the functionality was removed. The functions were rewritten I believe to not have that parameter at all.
It is just for pipes we previously used sync, no?
Robert Love
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