Messages in this thread | | | Date | Tue, 30 Dec 2003 13:23:26 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: 2.6.0 performance problems |
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On Tue, 30 Dec 2003, Thomas Molina wrote: > > The times for this operation is: > real 15m20s > user 0m35s > sys 0m20s
Ok. This looks much closer to the 2.4.x numbers you reported:
real 13m50.198s user 0m33.780s sys 0m15.390s
so I assume that we can consider this problem largely solved? There's still some difference, that could be due to just VM tuning..
I suspect that what happened is: - slab debugging adds a heavy CPU _and_ it also makes all the slab caches much less dense. - as a result, you see much higher system times, and you also end up needing much more memory for things like the dentry cache, so your memory-starved machine ended up swapping a lot more too.
> On my main system (1.3GHz Athlon, 512MB memory, fast hard drive; in other > words has plenty of resources) I get similar results, scaled down of > course. > > On 2.4 the times are > real 3m47s > user 14s > sys 7s > > On 2.6 the times are > real 3m27s > user 14s > sys 7s
So here 2.6.x actually outperforms 2.4.x
> I also get 90+ percent iowait under 2.6 and 0 iowait in 2.4.
This is likely just an issue of reporting. Under 2.6.x your idle time will be reported as iowait, while in your 2.4.x kernel you don't even have the iowait support, so all idle time is just "idle", and not split up into _why_ it is idle.
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