Messages in this thread | | | Date | Sat, 13 Mar 1999 14:03:26 +0100 | From | Andi Kleen <> | Subject | Re: [patch] kstat change to see how much Linux SMP really scale well |
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On Sat, Mar 13, 1999 at 01:10:07PM +0100, Andrea Arcangeli wrote: > >and global). With a modified top this gives a nice overview over locking > >problems. Patch relative to your patch. > > As I said to Pavel yesterday, the reason I didn't do that myself is simply > because I was worried to not break every software that uses /proc/stat. I > just thought and I perfectly agree with accounting separately the time the > kernel spent in spinning on the lock, but I was 99% sure that breaking the > /proc/stat in 2.2.3 I would had complains from everybody ;). > Breaking /proc/stat is something for 2.3.x not for 2.2.x according to me. > But note that I personally don't care to break it in 2.2.x I am an hacking > guy and I am not worried by hacking, recompiling and reinstalling all > software that are using it ;).
I would not call it breaking stat. Every /proc parser that does not know how to cope with additional fields is badly broken. I had expected that this ugly practice would have been stomped out by evolutionary methods in the 2.1 cycle - if not it is time. If you worry about this stuff it could be moved to a new /proc file too.
I do not expect this patch will get included in the 2.2.x series though, but of course it is a very useful feature for all these people bragging about SMP scalability @)
> > >I changed the lock accounting back to system, because it is really system > >time, but it is counted in the lock statistics too. To get pure (non locked) > >system overhead simply subtract the lock counter from the system time. > > Agreed. This is the way it should be done, if Linus will agree to break > /proc/stat and /proc/self/status in 2.2.4 I'm fine with this way too. > > >Probably only compiles on i386 because I didn't change non i386 > >update_one_process callers. To catch mistakes I moved the prototype > >into sched.h though. > > Another reason for not doing that was infact to not break all archs and > get a 2.2.4 that won't compile on Alpha again...
The changes are very simple. I can supply a patch.
> But I see a clever and more fun way to avoid losing ticks in both the irq > handler and in the smp timer interrupt, and it's to always calc the delta > between rdtsc inside the smp timer irq. I can go into that.
Exactly what I had in mind. Actually I'm surprised that Linux doesn't do that already @)
-Andi
-- This is like TV. I don't like TV.
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