[LITMUS^RT] How can I set total number of cores on G-EDF algorithm

[Luo, Zheng]

Hi everyone,

I want to use arbitrary number of cores to do run the global EDF. I tried several method, however none of them works for me. I think I truly need some help now.

1***
First, I tried the C-EDF, I think I can group the cores that will be used in the experiment to a cluster and the unused cores to a cluster. However, I read the documentation on the website, it showed how to use the L1,L2,L3 and ALL to do the division. I choose the parameter ALL, and run the experiment by choosing the ./setsched C_EDF. In the base_mt_task.c , I added:

CALL( init_rt_thread() );
int cluster = 0;
int cluster_sz = 4;
be_migrate_to_cluster(cluster, cluster_sz);
param.cpu   = cluster_to_first_cpu(cluster, cluster_sz);
CALL( set_rt_task_param(gettid(), &param) );

I tried different number of the cluster and cluster_sz, when I used the different number, I did the  method said in the website: C-EDF plugin must be reloaded (for example by switching to the Linux plugin and back to C-EDF). When I see the cpu utilization by run top -1, all 8 cores are being used. I get very confused here. I don't know where I did wrong. I send the screenshot as an attachment. I also send the base_mt_task.c as an attachment too.

2***
Second, I tried to use the G-EDF by disabling the cores in the linux system. I used:
sudo echo "0" > /sys/devices/system/node/node0/cpu1/online
sudo echo "0" > /sys/devices/system/node/node0/cpu3/online
Those command did disable the CPU cores, however the G-EDF seems not working correctly. The execution order of the rt_thread, seems not according to the G-EDF. Some of the late deadline thread, even finished early. I am really confused here.

3***
Third, I used the Native Linux user-space command to set the number of cores, by using
cpu_set_t mask;
CPU_ZERO(&mask);
for (unsigned i = first_core; i <= last_core; ++i) {
CPU_SET(i, &mask);
}
sched_setaffinity( 0 , sizeof(mask), &mask);
Then I run the experiment, and I will get same result as #1 method, it seems that G-EDF ignored the CPU mask setting.

I tired those three method, however none of them worked. Or is there any better idea to specify the number of online cores to run the experiment? I think I truly need some help now. Thank you very much. Looking forward to your reply.


Zheng Luo
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