cpu

问题 I have some heavy queries that are running offline on a sql database to manipulate data. the queries are running and sometimes take a significant part of the computer resources. Is there a way to control/adjust the CPU usage on in a given query / stored procedure? thanks 回答1: Per query you can use MAXDOP to limit number of CPUs used queries (when parallelism applies) You can't throttle CPU time or % If you have one CPU only, then your option is upgrade. However, CPU bound queries generally

问题 There doesn't seem to be any simple explanations on how to get CPU Percentage for a process in Powershell. I've googled it and searched here and I'm not seeing anything definitive. Can somebody explain in layman terms how to get CPU Percentage for a process? Thanks! Here's something to get you started ;) $id4u = gps | ? {$_.id -eq 412} function get_cpu_percentage { # Do something cool here } get_cpu_percentage $id4u 回答1: Using WMI: get-wmiobject Win32_PerfFormattedData_PerfProc_Process | ? {

问题 I am using VisualVM to monitor my JBoss instance. I have attached a screenshot of it aswell. The problem is after I restart the JBoss instance, the CPU on the OS starts to go high. Load can go as high as 40 and JAVA process in top command shows upto 300% usage. This then goes on to slow down the application at the front end. VisualVM shows that CPU is high and that thread count is increasing also. How can I further go to the root cause of this ? Visual VM output - General 回答1: When it comes

问题 I've been looking for an answer to this question for a day now and cant find a straight forward answer. I'm reading up on context switching waiting queues and stuff like that do get a good grasp of everything .And when reading an article there was written that when a convoy situation occurs, there will be a lot of context switching. So let me get this straight lets presume a thread is in a waiting queue for a mutex to unlock, does the cpu constantly context switch to that waiting thread to

问题 I am reading article about size_t in C/C++ http://web.archive.org/web/20081006073410/http://www.embedded.com/columns/programmingpointers/200900195 (link found through Stackoverflow). Quote from the article: Type size_t is a typedef that's an alias for some unsigned integer type, typically unsigned int or unsigned long, but possibly even unsigned long long. Each Standard C implementation is supposed to choose the unsigned integer that's big enough--but no bigger than needed-- to represent the

问题 I understand that: Faster access time > More expensive Slower access time > Less expensive I also understand that registers are the top of the hierarchy, and have the fastest access time. What I am having a hard time researching is why it's so expensive? To my knowledge, registers are literally circuits built directly into the ALU. If they're literally built into the CPU (the ALU especially), what actually makes it the most expensive? Is it the size (registers being the smallest, of course)?

问题 I've been using openCV quite a bit lately and I'm amazed at how fast it can process arrays. Is it using a special type of optimization or relying on special features of the CPU ? I'm on an Intel CPU btw. 回答1: OpenCV uses the Intel Integrated Performance Primitives under the hood. this library relies on aggressive optimization as well as careful use of special CPU features (SSE, SSE2, ...) 来源： https://stackoverflow.com/questions/2490187/what-sort-of-acceleration-does-opencv-use-how-can-it

问题 I am doing some cache performance measuring and I need to ensure the caches are empty of "useful" data before timing. Assuming an L3 cache is 10MB would it suffice to create a vector of 10M/4 = 2,500,000 floats, iterate through the whole of this vector, sum the numbers and that would empty the whole cache of any data which was in it prior to iterating through the vector? 回答1: Yes, that should be sufficient for flushing the L3 cache of useful data. I have done similar types of measurements and

问题 I am trying to use GNU coreutil top's formula for calculating CPU usages in percentage. But top is using some half_total, to calculate the percentage, which is adding 0.5 to the percentage. In utils.c of top's source, the following line (at 3.8 beta1, it is in line number: 459): - *out++ = (int)((*diffs++ * 1000 + half_total) / total_change); This translates to : ( (*diffs++ * 1000) / total_change ) + 1/2 So, it always gives a number, which is: "10 times the percentage, plus 0.5". So if the

问题 Your CPU does not support VT-x. Intel HAXM is required to run this AVD. Your CPU does not support VT-x. Unfortunately, your computer does not support hardware accelerated virtualization. Here are some of your options: 1) Use a physical device for testing 2) Develop on a Windows/OSX computer with an Intel processor that supports VT-x and NX 3) Develop on a Linux computer that supports VT-x or SVM 4) Use an Android Virtual Device based on an ARM system image (This is 10x slower than hardware