Andrew Morton wrote Wednesday, March 09, 2005 6:26 PM > What does "1/3 of the total benchmark performance regression" mean? One > third of 0.1% isn't very impressive. You haven't told us anything at all > about the magnitude of this regression.
2.6.9 kernel is 6% slower compare to distributor's 2.4 kernel (RHEL3). Roughly 2% came from storage driver (I'm not allowed to say anything beyond that, there is a fix though). 2% came from DIO. The rest of 2% is still unaccounted for. We don't know where. > How much system time? User time? All that stuff. 20.5% in the kernel, 79.5% in user space. > But the first thing to do is to work out where the cycles are going to. You've seen the profile. That's where all the cycle went. > Also, I'm rather peeved that we're hearing about this regression now rather > than two years ago. And mystified as to why yours is the only group which > has reported it. 2.6.X kernel has never been faster than the 2.4 kernel (RHEL3). At one point of time, around 2.6.2, the gap is pretty close, at around 1%, but still slower. Around 2.6.5, we found global plug list is causing huge lock contention on 32-way numa box. That got fixed in 2.6.7. Then comes 2.6.8 which took a big dip at close to 20% regression. Then we fixed 17% regression in the scheduler (fixed with cache_decay_tick). 2.6.9 is the last one we measured and it is 6% slower. It's a constant moving target, a wild goose to chase. I don't know why other people have not reported the problem, perhaps they haven't got a chance to run transaction processing db workload on 2.6 kernel. Perhaps they have not compared, perhaps they are working on the same problem. I just don't know. - Ken - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
