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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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Is there a way to take advantage of multi-core when dealing with network connections?

When we doing network programming, no matter you use multi-process, multi-thread or select/poll(epoll), there is only one process/thread to deal with accept the connection on same port. And if you want to take advantage of multi-cores, you need to…
easy
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I have a cpu cache coherency-looking problem that I can't figure out how to fix. Two cpus see different contents of the same memory

I have a really weird problem I can't figure out, I haven't seen anything this unexplainable in my 30+ years of programming. Clearly I'm doing something wrong, but can't figure out what, and I can't even figure out a way around it. I have a linux…
stu
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How could I know which core a process is running on?

I am currently working on a project about setting process to one core in linux environment. I use sched_setaffinity to do this job and I wonder whether there are some functions provided by linux to get which core the process is running on. I use…
terry
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by which instruction the secondary core is triggered while starting the secondary cpu

the booting of secondary cpu is initiated by the primary core. and some work is completed on the primary cpu and some is completed on the secondary cpu to complete the hotplug operation for cpu_up. I am trying to find the exact instruction that is…
Pankaj Gupta
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What are the differences between Symmetric Multiprocessing (SMP) and Multiprocessing (MP)?

I know MP is the manage of multiple processes within multiple processors, but is there any difference between that and SMP? Is it that in SMP you can execute multiple threads from the same process simultaniously, and MP you can only have one process…
Jwags
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What is the best way for interprocessor communication in Linux?

I have two CPUs on the chip and they have a shared memory. This is not a SMP architecture. Just two CPUs on the chip with shared memory. There is a Unix-like operating system on the first CPU and there is a Linux operating system on the second…
Sergey Smelov
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Is it faster to avoid writes when the values might be the same

On SMP machines is there a performance benefit to #2 vs #1: 1) x = 0; or 2) if (x) x = 0; I was thinking that the behind the scenes overhead to manage cache coherency between the CPUs might have some cost. Am I nuts?
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Setting affinity in multicore x86 processors

( I ask because it was before serious SMP and multicore that I studied OS. I like to have some vision of how code is being executed. ) If I have a multicore x86 CPU booting directly into my program. Can someone recommend a website which describes…
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Best hardware/software solution for parallel makes?

We've got a Linux-based build system in which a build consists of many different embedded targets (with correspondingly different drivers and featuresets enabled), each one built with another single main source tree. Rather than try to convert our…
Allan Anderson
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nr_cpu_ids vs NR_CPUS in Linux Kernel

I am trying to understand how many processors are supported by Linux Kernel. grep NR_CPUS /boot/config-`uname -r` Will give me the maximum number of processors supported by kernel, which I can override using kernel command line parameter…
md.jamal
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How would the MONITOR instruction (_mm_monitor intrinsic) be used by a driver?

I am exploring the usage of MONITOR instruction (or the equivalent intrinsic, _mm_monitor). Although I found literature describing them, I could not find any concrete examples/samples on how to use it. Can anyone share an example of how this…
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nr_cpus boot parameter in Linux kernel

I was browsing Linux kernel code to understand the nr_cpus boot parameter. As per the documentation, (https://www.kernel.org/doc/Documentation/kernel-parameters.txt) [SMP] Maximum number of processors that an SMP kernel could support. …
alex
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U-boot will run on single core?

I am working on TI Jacinto6(ARM CortexA15) based board. I am understanding U-boot source. As per start.S file, following assembly instructions are executed to disable L1 I/D cache and TLB. This instructions are from…
user3693586
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Processor affinity settings for Linux kernel modules?

In Windows, I can set the processor affinity of driver code using KeSetSystemAffinityThread, and check which processor my code is running on using KeGetCurrentProcessorNumber. I'm trying to do something similar in a Linux kernel module, but the only…
Stephen
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what is the basic concept behind using pen_release in the starting the cpus in linux

in linux kernel smp, pen_release identifier is used starting the secondary cpus, also i have found that it is being used in other places as well. I have checked its values in the sysdump, also tried understanding it with the lauterbach setup but…
Pankaj Gupta
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