Messages in this thread | | | From | Con Kolivas <> | Subject | Re: smp 'nice' bias support breaks scheduler behavior | Date | Thu, 26 Jan 2006 23:25:04 +1100 |
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On Thursday 26 January 2006 21:52, Siddha, Suresh B wrote: > Con, > > > [PATCH] sched: implement nice support across physical cpus on SMP > > I don't see imbalance calculations in find_busiest_group() take > prio_bias into account. This will result in wrong imbalance value and > will cause issues.
in 2.6.16-rc1:
find_busiest_group(....
load = __target_load(i, load_idx, idle); else load = __source_load(i, load_idx, idle);
where __target_load and __source_load is where we take into account prio_bias.
I'm not sure which code you're looking at, but Peter Williams is working on rewriting the smp nice balancing code in -mm at the moment so that is quite different from current linus tree.
Con
> > For example on a DP system with HT, if there are three runnable processes > (simple infinite loop with same nice value), this patch is resulting in > bouncing of these 3 processes from one processor to another...Lets assume > if the 3 processes are scheduled as 2 in package-0 and 1 in package1.. > Now when the busy processor on package-1 does load balance and as > imbalance doesn't take "prio_bias" into account, this will kick active > load balance on package-0.. And this is continuing for ever, resulting > in bouncing from one processor to another. > > Even when the system is completely loaded and if there is an imbalance, > this patch causes wrong imabalance counts and cause unoptimized > movements. > > Do you want to look into this and post a patch for 2.6.16? > > thanks, > suresh - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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