Hi hackers,
I am a little bit confused about the term of cpu and core in l4linux. I have a system with 8 processor intel xeon E5606 with 4 cores in each cpu. I'm going to maximize it to become the maximum number of cores in all cpus. But I am confused in determining the l4x_cpus that what is the term cpu in here? Is it literally cpu or the number of threads that can be handled in each core?
I run an openmp hello world apps over l4linux. I call the omp_get_thread_num() and I got 4 threads in the result. Are these 4 threads obtained from 4 cores in single cpu? So, if I'm right, how can I optimize to use all of the cpu existed in the system? I've tried to use l4x_cpus=8 and l4x_cpus=32, but those commands doesn't work for me. In my opinion, if I can maximize until the maximum number of cores and I have 32 threads that run concurrently, then it will be served by each core in those 8 cpus.
In fiasco configuration, there is maximal supported number of CPUs. So referring to my case, the maximum is supposed to be 8, am I right? In case of thread migration in example ex_thread_migrate, I create 16 threads and will be migrated to each cpu. Here is the result: migrate | Migrated Thread00 -> CPU02 migrate | Migrated Thread01 -> CPU03 migrate | Migrated Thread02 -> CPU04 migrate | Migrated Thread03 -> CPU05 migrate | Migrated Thread04 -> CPU06 migrate | Migrated Thread05 -> CPU07 migrate | Migrated Thread06 -> CPU00 migrate | Migrated Thread07 -> CPU01 migrate | Migrated Thread08 -> CPU02 migrate | Migrated Thread09 -> CPU03 migrate | Migrated Thread10 -> CPU04 migrate | Migrated Thread11 -> CPU05 migrate | Migrated Thread12 -> CPU06 migrate | Migrated Thread13 -> CPU07 migrate | Migrated Thread14 -> CPU00 migrate | Migrated Thread15 -> CPU01
My question is do the thread00 and thread08 share the same core in CPU02 or they use different core in CPU02 which run concurrently? And also, is it normal to get the output like cpu[1] to cpu[7] goes to idle loop?
Thanks,
Irvanda
Hi,
On Thu Apr 24, 2014 at 16:47:59 +0900, Irvanda Kurniadi wrote:
I am a little bit confused about the term of cpu and core in l4linux. I have a system with 8 processor intel xeon E5606 with 4 cores in each cpu.
According to the Internet, an E5606 is a quadcore CPU without hyperthreading. Do you mean that you have an 8 socket system and thus 32 cores?
I'm going to maximize it to become the maximum number of cores in all cpus. But I am confused in determining the l4x_cpus that what is the term cpu in here? Is it literally cpu or the number of threads that can be handled in each core?
l4x_cpus describes how many virtual CPU (L4) threads L4Linux shall create. This is purely software and has no relation to Hyperthreads or similar.
I run an openmp hello world apps over l4linux. I call the omp_get_thread_num() and I got 4 threads in the result. Are these 4 threads
So you L4Linux is running with 4 vCPUs? (See /proc/cpuinfo for example.)
obtained from 4 cores in single cpu? So, if I'm right, how can I optimize to use all of the cpu existed in the system? I've tried to use l4x_cpus=8 and l4x_cpus=32, but those commands doesn't work for me. In my opinion, if
Doesn't work means it does not get larger than 4? Your L4Linux configuration also needs to support as many CPUs.
I can maximize until the maximum number of cores and I have 32 threads that run concurrently, then it will be served by each core in those 8 cpus.
Yes, that should work this way.
In fiasco configuration, there is maximal supported number of CPUs. So referring to my case, the maximum is supposed to be 8, am I right? In case
I'm not sure. The number should be nr_sockets * nr_cores * nr_hyperthreads.
of thread migration in example ex_thread_migrate, I create 16 threads and will be migrated to each cpu. Here is the result: migrate | Migrated Thread00 -> CPU02 migrate | Migrated Thread01 -> CPU03 migrate | Migrated Thread02 -> CPU04 migrate | Migrated Thread03 -> CPU05 migrate | Migrated Thread04 -> CPU06 migrate | Migrated Thread05 -> CPU07 migrate | Migrated Thread06 -> CPU00 migrate | Migrated Thread07 -> CPU01 migrate | Migrated Thread08 -> CPU02 migrate | Migrated Thread09 -> CPU03 migrate | Migrated Thread10 -> CPU04 migrate | Migrated Thread11 -> CPU05 migrate | Migrated Thread12 -> CPU06 migrate | Migrated Thread13 -> CPU07 migrate | Migrated Thread14 -> CPU00 migrate | Migrated Thread15 -> CPU01
My question is do the thread00 and thread08 share the same core in CPU02 or they use different core in CPU02 which run concurrently? And also, is it
CPU here means a hyperthread (assuming there is just one hyperthread per core, it also means a core).
normal to get the output like cpu[1] to cpu[7] goes to idle loop?
Yes, it's an informational message by the kernel.
Adam
On Fri, Apr 25, 2014 at 6:40 AM, Adam Lackorzynski < adam@os.inf.tu-dresden.de> wrote:
Hi,
On Thu Apr 24, 2014 at 16:47:59 +0900, Irvanda Kurniadi wrote:
I am a little bit confused about the term of cpu and core in l4linux. I have a system with 8 processor intel xeon E5606 with 4 cores in each cpu.
According to the Internet, an E5606 is a quadcore CPU without hyperthreading. Do you mean that you have an 8 socket system and thus 32 cores?
Yes I do, it means 8 sockets.
I'm going to maximize it to become the maximum number of cores in all
cpus.
But I am confused in determining the l4x_cpus that what is the term cpu
in
here? Is it literally cpu or the number of threads that can be handled in each core?
l4x_cpus describes how many virtual CPU (L4) threads L4Linux shall create. This is purely software and has no relation to Hyperthreads or similar.
I run an openmp hello world apps over l4linux. I call the
omp_get_thread_num() and I got 4 threads in the result. Are these 4
threads
So you L4Linux is running with 4 vCPUs? (See /proc/cpuinfo for example.)
OK, I got it. I put 32 in l4x_cpus, then I check it in /proc/cpuinfo. I
found that there are only 25 vCpus created from vcpu 0 - 24. At the second attempt, there are 28 vCpus created. At the third attempt, there are 32 vCpus created. Then at fourth attempt there are 31 vCpus created. The number of vCpu created isn't always shown with the certain number. Is it normal? I don't think this is a normal condition.
obtained from 4 cores in single cpu? So, if I'm right, how can I optimize to use all of the cpu existed in the system? I've tried to use l4x_cpus=8 and l4x_cpus=32, but those commands doesn't work for me. In my opinion,
if
Doesn't work means it does not get larger than 4? Your L4Linux configuration also needs to support as many CPUs.
Yeah, the problem is located in fiasco and smp (on qemu) configuration. After I read your explanation, I change the max cpus into nr_sockets*nr_cores and also change the smp into -smp 32.
regards, Irvanda
On Fri Apr 25, 2014 at 11:01:24 +0900, Irvanda Kurniadi wrote:
On Fri, Apr 25, 2014 at 6:40 AM, Adam Lackorzynski < adam@os.inf.tu-dresden.de> wrote:
On Thu Apr 24, 2014 at 16:47:59 +0900, Irvanda Kurniadi wrote:
I am a little bit confused about the term of cpu and core in l4linux. I have a system with 8 processor intel xeon E5606 with 4 cores in each cpu.
According to the Internet, an E5606 is a quadcore CPU without hyperthreading. Do you mean that you have an 8 socket system and thus 32 cores?
Yes I do, it means 8 sockets.
I'm going to maximize it to become the maximum number of cores in all
cpus.
But I am confused in determining the l4x_cpus that what is the term cpu
in
here? Is it literally cpu or the number of threads that can be handled in each core?
l4x_cpus describes how many virtual CPU (L4) threads L4Linux shall create. This is purely software and has no relation to Hyperthreads or similar.
I run an openmp hello world apps over l4linux. I call the
omp_get_thread_num() and I got 4 threads in the result. Are these 4
threads
So you L4Linux is running with 4 vCPUs? (See /proc/cpuinfo for example.)
OK, I got it. I put 32 in l4x_cpus, then I check it in /proc/cpuinfo. I
found that there are only 25 vCpus created from vcpu 0 - 24. At the second attempt, there are 28 vCpus created. At the third attempt, there are 32 vCpus created. Then at fourth attempt there are 31 vCpus created. The number of vCpu created isn't always shown with the certain number. Is it normal? I don't think this is a normal condition.
Fiasco does not wait starting programs on CPU0 until all CPUs are up (actually it does not know when this is the case). In your case L4Linux is already booting when other CPUs are still booting up. So waiting a bit should make all CPUs available to L4Linux.
Adam
l4-hackers@os.inf.tu-dresden.de
-
Adam Lackorzynski -
Irvanda Kurniadi