cpu | 易学教程

FLOPS Intel core and testing it with C (innerproduct)

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问题 I have some misconceptions about measuring flops, on Intel architecture, is a FLOP one addition and one multiplication together? I read about this somewhere online and there is no debate that could reject this. I know that FLOP has a different meaning on different types of cpu. How do I calculate my theoretical peak FLOPS? I am using Intel(R) Core(TM)2 Duo CPU E7400 @ 2.80GHz. What exactly is the relationship between GHz and FLOPS? (even wikipedia's entry on FLOPS does NOT specify how to do

Does GRUB switch to protected mode?

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I would like to ask if it is GRUB that switch the CPU to protected mode during boot up or is it the Linux kernel that does it. And also I would like to ask - is the kernel itself (vmlinuz) an ELF or is it plain binary format? Thanks. GRUB does drop you in protected mode. The GRUB Multiboot Specification (version 0.6.96) Section 3.2 tells you this ‘CR0’ Bit 31 (PG) must be cleared. Bit 0 (PE) must be set. Other bits are all undefined. And CR0 Register mapping tells you that the system should be in protected mode. Linux is not a multiboot kernel and does not rely on some bootloader for switching

How is an LRU cache implemented in a CPU?

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问题 I'm studying up for an interview and want to refresh my memory on caching. If a CPU has a cache with an LRU replacement policy, how is that actually implemented on the chip? Would each cache line store a timestamp tick? Also what happens in a dual core system where both CPUs write to the one address simultaneously? 回答1: For a traditional cache with only two ways, a single bit per set can be used to track LRU. On any access to a set that hits, the bit can be set to the way that did not hit.

Invalidating the CPU's cache

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问题 When my program performs a load operation with acquire semantics/store operation with release semantics or perhaps a full-fence, it invalidates the CPU's cache. My question is this: which part of the cache is actually invalidated? only the cache-line that held the variable that I've used acquire/release? or perhaps the entire cache is invalidated? (L1 + L2 + L3 .. and so on?). Is there a difference in this subject when I use acquire/release semantics, or when i use a full-fence? 回答1: I'm not

Predicting DXL Memory and CPU Usage

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Has anyone had any success in predicting or profiling DXL applications for memory and CPU usage? I have a script that opens, closes, and modifies modules, possibly hundreds or even thousands of modules. I want to know, or least have a rough idea, how many modules I can run through the script before running out of memory. Cross posts: http://smartdxl.com/forum/viewtopic.php?f=1&t=602 https://www.ibm.com/developerworks/community/forums/html/topic?id=c5d4cc33-9986-463e-a73b-36523e6add7a&ps=25 来源： https://stackoverflow.com/questions/19422567/predicting-dxl-memory-and-cpu-usage

how to get android cpu temperature programmatically

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Tried this but got 0.0 and on physical device nothing found.. Any way to get cpu temperature in android SensorManager mySensorManager = (SensorManager) getSystemService(SENSOR_SERVICE); Sensor AmbientTemperatureSensor = mySensorManager.getDefaultSensor(Sensor.TYPE_AMBIENT_TEMPERATURE); if (AmbientTemperatureSensor != null) { mySensorManager.registerListener( AmbientTemperatureSensorListener, AmbientTemperatureSensor, SensorManager.SENSOR_DELAY_NORMAL); } private final SensorEventListener AmbientTemperatureSensorListener = new SensorEventListener() { @Override public void onAccuracyChanged

Thrust: How to directly control where an algorithm invocation executes?

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The following code has no information that may lead it to run at CPU or GPU. I wonder where is the "reduce" operation executed? #include <thrust/iterator/counting_iterator.h> ... // create iterators thrust::counting_iterator<int> first(10); thrust::counting_iterator<int> last = first + 3; first[0] // returns 10 first[1] // returns 11 first[100] // returns 110 // sum of [first, last) thrust::reduce(first, last); // returns 33 (i.e. 10 + 11 + 12) Furthermore, thrust::transform_reduce( thrust::counting_iterator<unsigned int>(0), thrust::counting_iterator<unsigned int>(N), MyOperation(data), 0

NodeJS CPU spikes to 100% one CPU at a time

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问题 I have a SOCKS5 Proxy server that I wrote in NodeJS. I am utilizing the native net and dgram libraries to open TCP and UDP sockets. It's working fine for around 2 days and all the CPUs are around 30% max. After 2 days with no restarts, one CPU spikes to 100%. After that, all CPUs take turns and stay at 100% one CPU at a time. Here is a 7 day chart of the CPU spikes: I am using Cluster to create instances such as: for (let i = 0; i < Os.cpus().length; i++) { Cluster.fork(); } This is the

How do you disable the CPU window in Delphi 7

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问题 When stepping a program in Delphi 7, the CPU window sometimes pops up and then steps through that instructions. I find this an annoyance as I wish to only step Pascal Code. Does anyone know how to disable this CPU pop-up? I would not be sorry if this window never ever shows. It did not happen on Delphi 5 which was my previous IDE that I used for Delphi. I do use the Step-Over button mostly and only step-into when wanting to get into detail of a used (pascal) unit. 回答1: Delphi does not, by

tensorflow build - CPU / MKL / Windows

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Has anyone succeeded to build tensorflow python wheel with the following configuration: CPU (not GPU) OS: Windows 7 / server 2012 Using Intel MKL and/or mkl-dnn Python 3.6 I am struggling, for days now, trying to tweak bazel files and cmake files without success. Would like to know if someone succeeded and willing to share what he did . Thanks, Lior Solution: 1 Installing TensorFlow from Source on windows is not generally supported. But you can try building this using bazel or tensorflow cmake build. Refer: https://www.tensorflow.org/install/install_sources Solution: 2 Create Intel optimized