With typical mechanical hard drive seek times are around 10 milliseconds, the processor is capable of executing 100 million instructions in the time it takes to read a value from the hard drive. With a cycle time of 0.4 ns, the processor can execute 10 instructions per nanosecond. In 2014, a typical processor core operates at 2.5 GHz and may be able to execute 4 instructions per cycle. This reduces the time the CPU spends idle, as the CPU can perform millions of operations instead of sitting idle.Ĭonsider a thread that needs to read data off a hard drive. If a thread is waiting for a resource (such as loading a value from RAM into a register, disk I/O, network access, launch a new process, query a database, or wait for user input), the processor can work on a different thread, and return to the first thread once the resource is available. Partitioning the work this way allows your application to rely on the operating system to schedule what to do next with the cpu, so you don't have to make explicit conditional checks everywhere in your application about what might block and what's ready to process. #IGETTER MORE THREADS CODE#The code for each of these will exhibit a clean, purposeful flow, without having to make explicit checks that there isn't something else to do. The worker thread can work on inputs from a number of other sources. For instance, one thread might block waiting on input from a socket, parse the stream into messages, filter messages, and when a valid message comes along, pass it off to some other worker thread. The single thread spends most of its time polling this, checking on that, conditionally calling routines as needed, and it becomes hard to see anything but a morass of minutiae.Ĭontrast this with the case where you can dedicate threads to tasks so that, looking at any individual thread, you can see what that thread is doing. In even a moderately complex application, using a single thread try to do everything quickly makes hash of the 'flow' of your code. The point is that, despite not getting any real speedup when thread count exceeds core count, you can use threads to disentangle pieces of logic that should not have to be interdependent. Finally, unless your program is truly performance-critical, don't worry too much :) You may find it more useful to think in terms of tasks or jobs, rather than threads: write objects of work and give them to a pool to be run. Figure out the number of threads you need based on profiling and measurement. So: stealing time isn't a bad thing (and isn't really theft, either: it's how the system is supposed to work.) Write your multithreaded programs based on the kind of work the threads will do, which may not be CPU-bound. I'm not certain why they do this, but my guess is to do with the size of the tasks that are given to run on the threads. Net threadpool has up to 250 threads available per processor. It might seem to make sense to have the same number of threads as cores, yet the. If you have work that needs to be run, one common mechanism is to use a threadpool. The moment it uses disk or network I/O, for example, it may be potentially spend time waiting doing nothing useful. It's rare for a thread to genuinely need 100% CPU. What if you have five bits of work that all need to be done at once? It makes more sense to run them all at once, than to run four of them and then run the fifth later. It's actually more complicated than that: If a thread is not working 100% (as a UI thread might not be, or a thread doing a small amount of work or waiting on something else) then another thread being scheduled is actually a good situation. With that as background, the answer: Yes, more than four threads on a true four-core machine may give you a situation where they 'steal time from each other', but only if each individual thread needs 100% CPU. (Well, you might if it's running real-time, if you're using a realtime OS or, even on Windows, use a real-time thread priority. You won't ever get a situation where a thread runs without having time 'stolen' from it. You probably have several hundred threads all running on your machine right now. If you are running any modern OS, every process has at least one thread, and many have more. Even if you have four cores and four working threads, your process and it threads will constantly be being switched out for other processes and threads. In an 'ideal' system, you would have one thread executing per core: no interruption. The answer revolves around the purpose of threads, which is parallelism: to run several separate lines of execution at once.
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Mooze - Mechanized Patrol (multiplayer music), Rads Pt1 (outtake) (ABR version).Cut X-Ray pack 1 for CoP 1.6.02 (first person death) by SkyLoader.SWTC COP (few sun presets) by Vincent Vega.Foggy sky textures by Cromm Cruac from Autumn Aurora 2.1 by Autumn Wanderers.Shocker HQ geometry by Shoker team (Ported by PYP).Widescreen Scope Fix by DoctorX from EpicStalkerForum.Re-skinned Gloves for COP by AdayDr1en and HeNe (Used as overlay for sharpness).Freedom exo sleeves from Outfit Addon 1.4.7 by VodkaChicken.ShWM v2.1 by Shoker Team (sweater model, helmet variations made by PYP).Ezio_Auditore900 - deleted stashes (ABR version).Weapon condition depending on the fraction by WinCap from AMK-Forum 09.04.17.Advanced Detectors by ExtremeAlpaca (ABR version). #S.t.a.l.k.e.r. 2. modPGO7V scope model by Paul Yakushev, textures by Gunslinger mod.30,45 and 60rnd mags for AK74(5.45x39) by Paul Yakushev.Arsenal Overhaul 3.1 by E.Nigma42 and many others.STCOP 2.8\3.2\3.3 by Ga2z |
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