Messages in this thread | | | Date | Wed, 07 Nov 2012 20:42:02 +0800 | From | Alex Shi <> | Subject | Re: [RFC PATCH 2/3] sched: power aware load balance, |
| |
On 11/07/2012 03:51 AM, Andrew Morton wrote: > On Tue, 6 Nov 2012 21:09:58 +0800 > Alex Shi <alex.shi@intel.com> wrote: > >> $for ((i=0; i < I; i++)) ; do while true; do : ; done & done >> >> Checking the power consuming with a powermeter on the NHM EP. >> powersaving performance >> I = 2 148w 160w >> I = 4 175w 181w >> I = 8 207w 224w >> I = 16 324w 324w >> >> On a SNB laptop(4 cores *HT) >> powersaving performance >> I = 2 28w 35w >> I = 4 38w 52w >> I = 6 44w 54w >> I = 8 56w 56w >> >> On the SNB EP machine, when I = 16, power saved more than 100 Watts. > > Confused. According to the above table, at I=16 the EP machine saved 0 > watts. Typo in the data?
Not typo, since the LCPU number in the EP machine is 16, so if I = 16, the powersaving policy doesn't work actually. That is the patch designed for race to idle assumption.
The result looks same as the third patch(for fork/exec/wu) applied. Result put here because it is from this patch.
> > > Also, that's a pretty narrow test - it's doing fork and exec at very > high frequency and things such as task placement decisions at process > startup might be affecting the results. Also, the load will be quite > kernel-intensive, as opposed to the more typical userspace-intensive > loads.
Sorry, why you think it keep do fork/exec? It just generate several 'bash' task to burn CPU, without fork/exec.
with I = 8, on my 32 LCPU SNB EP machine: No do_fork calling in 5 seconds.
$ sudo perf stat -e probe:* -a sleep 5 Performance counter stats for 'sleep 5': 3 probe:do_execve [100.00%] 0 probe:do_fork [100.00%]
And it is not kernel-intensive, it nearly running all in user level.
'Top' output: 25:0%us VS 0.0%sy
Tasks: 319 total, 9 running, 310 sleeping, 0 stopped, 0 zombie Cpu(s): 25.0%us, 0.0%sy, 0.0%ni, 74.5%id, 0.4%wa, 0.1%hi, 0.0%si, 0.0%st ...
> So, please run a broader set of tests so we can see the effects? >
Really, I have no more ideas for the suitable benchmarks.
Just tried the kbuild -j 16 on the 32 LCPU SNB EP, power just saved 10%, but compile time increase about ~15%. Seems if the task number is variation around the powersaving criteria number, that just cause trouble.
-- Thanks Alex
| |