Messages in this thread |  | | | Date | Tue, 3 Nov 2009 18:45:31 +0100 | | From | Ingo Molnar <> | | Subject | Re: UDP-U stream performance regression on 32-rc1 kernel |
| |
* Zhang, Yanmin <yanmin_zhang@linux.intel.com> wrote:
> On Tue, 2009-11-03 at 11:47 +0800, Alex Shi wrote: > > We found the UDP-U 1k/4k stream of netperf benchmark have some > > performance regression from 10% to 20% on our Tulsa and some NHM > > machines. > perf events shows function find_busiest_group consumes about 4.5% cpu > time with the patch while it only consumes 0.5% cpu time without the > patch. > > The communication between netperf client and netserver is very fast. > When netserver receives a message and there is no new message > available, it goes to sleep and scheduler calls idle_balance => > load_balance_newidle. load_balance_newidle spends too much time and a > new message arrives quickly before load_balance_newidle ends. > > As the comments in the patch say hackbench benefits from it, I tested > hackbench on Nehalem and core2 machines. hackbench does benefit from > it, about 6% on nehalem machines, but doesn't benefit on core2 > machines.
Can you confirm that -tip:
http://people.redhat.com/mingo/tip.git/README
has it fixed (or at least improved)?
Ingo -- 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/
|  |