cpu

问题 I have to split a huge file into many smaller files. Each of the destination files is defined by an offset and length as the number of bytes. I'm using the following code: private void copy(string srcFile, string dstFile, int offset, int length) { BinaryReader reader = new BinaryReader(File.OpenRead(srcFile)); reader.BaseStream.Seek(offset, SeekOrigin.Begin); byte[] buffer = reader.ReadBytes(length); BinaryWriter writer = new BinaryWriter(File.OpenWrite(dstFile)); writer.Write(buffer); }

问题 I have to split a huge file into many smaller files. Each of the destination files is defined by an offset and length as the number of bytes. I'm using the following code: private void copy(string srcFile, string dstFile, int offset, int length) { BinaryReader reader = new BinaryReader(File.OpenRead(srcFile)); reader.BaseStream.Seek(offset, SeekOrigin.Begin); byte[] buffer = reader.ReadBytes(length); BinaryWriter writer = new BinaryWriter(File.OpenWrite(dstFile)); writer.Write(buffer); }

问题 I heard there is Intel book online which describes the CPU cycles needed for a specific assembly instruction, but I can not find it out (after trying hard). Could anyone show me how to find CPU cycle please? Here is an example, in the below code, mov/lock is 1 CPU cycle, and xchg is 3 CPU cycles. // This part is Platform dependent! #ifdef WIN32 inline int CPP_SpinLock::TestAndSet(int* pTargetAddress, int nValue) { __asm { mov edx, dword ptr [pTargetAddress] mov eax, nValue lock xchg eax,

问题 Just as an example, I want to know exactly which of the x86 processor families support the fisttp instruction. I'm pretty certain that it's supported on the Pentium 4 and beyond, but I'd like to have some official verification of that. And more importantly, I'd like to know if it is supported any further back: is it available on the Pentium III? I tried all the obvious Google search terms, but there's hardly anything at all available online about this particular instruction. And even if there

问题 How come CPU% in process is higher than in overall CPU Usage Percentage top - 19:42:24 up 68 days, 19:49, 6 users, load average: 439.72, 540.53, 631.13 Tasks: 354 total, 3 running, 350 sleeping, 0 stopped, 1 zombie Cpu(s): 21.5%us, 46.8%sy, 0.0%ni, 17.4%id, 0.0%wa, 0.1%hi, 14.2%si, 0.0%st Mem: 65973304k total, 50278472k used, 15694832k free, 28749456k buffers Swap: 19455996k total, 93436k used, 19362560k free, 14769728k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 4425 ladm 20

问题 so my... err... app does the following: listen on a queue for 'work' spawns about 100 workers per server (across ~3 servers), each listening on the queue each worker basically does some networky stuff (ssh, snmp etc) (i/o intensive), then churns the output (very cpu intensive) i have it all working under multiprocessing and it works great. however: each worker is using way more memory than i would like (about 30MB RES, 450MB VIRT according to top). so i have two questions: what is the best

问题 I usually run Runtime#availableProcessors to determine how many cores on a Windows computer and it works fine. The result is consistent with that I found from control panel. However when I applied the API on a Linux server, it returns 1 . As I know the server is more powerful it doesn't make sense to me it's a single cpu system. I did some search and found the Linux box is Intel(R) Xeon(R) CPU X5675 @ 3.07GHz , googling shows it has 6 cpu cores. Then the question is, why Runtime

问题 Site is an ecommerce site: 5 Million records in table Two servers: one for webserver and other contains mysql Search is happenning through Sphinx server. So search queries do not come to MySQL Mysql configuration: Dual Quad Core Zeoo 2.0, 146 GB, 16 GB RAM. Webserver configuration: Dual Quad Core Zeoo 2.0, 146 GB, 16 GB RAM. For past four days I find MySQL is using CPU continuously for at least 6-7 hours in a day. It becomes normal after that. Even if I restart, it doesnt stop. It again uses

问题 What's the difference between tms_utime and tms_stime exactly? I'm referring to the struct tms used by the POSIX times() function. Is the data caching time included in the utime ? Can the data caching time be measured separately? PS: I am using Linux-Ubuntu. For example, I am solving a large sparse linear equation system using my C++ program. 回答1: Given that you are discussing the tms_utime and tms_stime members of struct tms (which contains 4 elements of type clock_t ) used by times(), the

问题 I'm using a modified auditd package, and linked gprof with it. But from the output of gprof XX | gprof2dot | dot -Tpng output.png , all functions are 100% usage, so I cannot tell who's consuming most of the CPU resources. (Right click on the image to have a full view) Any ideas? Is that normal, and most importantly, how should I know which function consumes most CPU? P.S: original gprof output http://pastie.org/8546568 回答1: At the top of the flat profile (in the pastie.org link) is the