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Questions tagged [smp]

Symmetric multiprocessing

"Symmetric multiprocessing (SMP) involves a multiprocessor computer hardware architecture where two or more identical processors are connected to a single shared main memory and are controlled by a single OS instance. Most common multiprocessor systems today use an SMP architecture." [Source: Wikipedia.]

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Can printf() be made SMP safe?

I'm trying to get RTEMS running using SMP on a Leon3/gr712rc (2 cores). I have it partially running, but it crashes intermittently on printf's. Can anyone tell me if there's a way to make printf() SMP safe? printf appears to use termios which uses…
Symmetric
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How to invalidate cache on mmap'ed shared memory (multi processor machine)

I have two processes, sharing a memory area for fast communication. Both processes run the following (error check removed): int fd = open("/run/afile", O_RDWR ); void *ptr = mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); volatile…
Luis de Arquer
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for_each_possible_cpu macro in vmalloc_init() function, does the code run in only one cpu? or in every cpu?

this is not about programming, but I ask it here.. in linux start_kernel() function, in the mm_init() function, I see vmalloc_init() function. inside the function I see codes like this. void __init vmalloc_init(void) { struct vmap_area *va; …
Chan Kim
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Can't find WSL kernel directory not in /usr/src and not in /lib/modules

I am not a developer, and don't have enough experience with Linux. I am a data scientist and wants to know how to improve my performance using my CPUs better. I have a linux VM with 2 physical CPUs, with 15 logical cores with two logical processors…
gil.frenkel
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Confusion around spin_lock_irqsave: in what nested situation is interrupt state kept?

There are many Q&As about spinlocks, but it's still confusing to me. I think it's because the questions and answers assume different settings or not clearly explain the settings about if it's SMP or if it's preemptive kernel or not when they ask or…
Chan Kim
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Boost threads and non-existant speedups on Linux SMPs

I have written a small example C++ program, using boost::thread. Since it's 215 lines, I've posted it on pastebin instead http://pastebin.com/LRZ24W7D The program creates a large number of floats (currently 1gb) and adds them up, first sequentially,…
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Does any RTOS support SMP scheduling?

We have a project in which the SOC has multi-core like ARM Cortex-R8; so we want an open-source RTOS that supports SMP scheduling. But it seems that no RTOS supports SMP, at least from its official release version. Could anyone give the suggestion…
Randy
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Access "current_task" pointer of another cpu in a SMP based linux system

I'm writing some kernel driver where I need to check which thread is running at a certain point on another cores. My driver runs one kernel thread on per core and I need to sync from time to time some of the threads to do certain task. What I can…
mdaniel
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Use case linux kernel: bring cores in idle in a SMP system

I've got recently a task to implement a use case in the linux kernel. Due to some confidential info I cannot explain all details, but I'll try to do my best to explain our goal, what is known and what not. We have a linux distro that runs on a smp…
mdaniel
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threads of one process can run on more than one physical CPUs?

on Linux, we have two physical CPUs (not multi-cores), one process named X has many threads. Question is if it is possible: some threads of X running on one CPU, while some other threads of X running on the other CPU at the same time??
worldwalk
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Why is value written by one CPU not seen by the other?

Sorry if this is very basic. This is a simplified version of what I'm doing. I'm writing a kernel module. When it's running there will be two threads one two different physical CPU. I'm using a global variable to do certain communication between…
TFC
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Linux support for AMP architecture?

When I search about linux kernel, I know that linux support for SMP architecture. But I don't find any specification about the linux for AMP. Does linux support for AMP? Have any documents or specification for descripting about that? Anyone help?
bvp147
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SMP affinity vs XPS on paired queues and TX queue selection control

I have a solarflare nic with paired rx and tx queues (8 sets, 8 core machine real machine, not hyperthreading, running ubuntu) and each set shares an IRQ number. I have used smp_affinity to set which irqs are processed by which core. Does this…
Nidhi
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How to Use DateTime of ODATA (SMP 9.0 and above) in Android

I am getting ODATA from SMP from that ODATA. When we are trying to fetch Datetime and setting into Java Date getting an Exception. How to Typecast ODATA DateTime to Java Date in Android (SMP 9.0 and above)?
ranjan
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Hypervisor SMP Issue

previously thank you for read my Question. I'm implementing 'SMP' work on my hypervisor project. What i want to do is like bellow. One virtual machine have two vcpus. And this Virtual Machine is working on 2 pCPU. For example, one linux has 2 cpu…
Jeungwoo Yoo
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