Author: Bob Durrett
Date: 18:33:24 11/11/02
Go up one level in this thread
On November 11, 2002 at 21:17:01, Robert Hyatt wrote: >On November 11, 2002 at 15:41:48, Bob Durrett wrote: >> >>I am a non-programmer but assume that all professional programmers know all >>about optimizers. Sounds like a good thing to have, anyway. : ) >> >>So far, we have been talking about the case where there is only one big program >>running on the computer and that is the chess engine [& GUI maybe]. But many >>people [I presume] also run Office or Word and maybe other software. I almost >>always have CB8 running when using Fritz, for example. Perhaps running several >>big programs at once would cause the operating system to be more busy? >> > >Yes, but the overhead for such is expected and all systems will lose a tiny >bit of time doing context switches. Some worse than others. But the usage >Vincent was describing makes no sense, as he said "one console program". > Not clear. Like multiple PCs but only one monitor and keyboard? Or, multiple processors with shared memory and shared monitor and keyboard? Not clear what Vincent was discussing in that case. Relevance to main question unclear. Could it be that operating systems might have more work to do in that case? If SMP, then communication between processors considered to be an operating system function? If so, how much % of total processor time for that? Please forgive me if my ignorance regarding operating systems is showing. : ( > >>We have also been assuming that the computer would have ample RAM. However, >>maybe not everybody has an expensive computer with tons of RAM. There may be >>competition for the available RAM, and the OS would be one of the competitors. >> >>So, can the conclusions reached so far be extended to these cases too? >> > >No system pages efficiently, but that is a totally different issue to >operating system overhead in normal usage. > > >>Incidentally, why would the Fritz people write their program in assembly >>language, essentially bypassing an "optimizer"? Does it make enough difference >>to go to that much trouble? [Maybe the Fritz people think only in assembly >>language? : ) ] >> > > >Because you can do better than the optimizer. You design the program, so >you know more about the internals of the program. IE if you want to do some- >thing like wtm=!wtm; the optimizer has to handle cases where wtm can be >_any_ legal integer value. If I know that it is only zero or one, I can >change that to a much faster XOR instruction. Because I know something the >compiler doesn't. Ditto for lots of other common things. A switch. I don't >have to check for the "out-of-range" values, as I _know_ there will be none. > >etc... > > I may be asking a question no one can answer, but: "How much difference would that make?" "100 rating points?" I'm still looking for a "bottom line" here, such as a conclusion or executive summary of findings, or whatever. Something profound, preferably. : ) Bob D. > > > > >>P.S. Note that I am trying to use plenty of smileys whenever I intend humor. >> >>Bob D. >> >> >> >>> >>> >>> >>> >>> >>>>>On November 11, 2002 at 13:02:44, Bob Durrett wrote: >>>>> >>>>>>Would the engine perform significantly better using that dedicated operating >>>>>>system? [As compared to using a commercially available OS] >>>>> >>>>>You can get an idea of how much time is used by the OS. On my computer I look >>>>>under Task Manager and it says: >>>>> >>>>>Image Name CPU Time >>>>>System Idle Process 6:19:14 >>>>>IEXPLORE.EXE 0:02:16 >>>>>msdev.exe 0:01:22 >>>>>Explorer.exe 0:00:53 >>>>>System 0:00:22 >>>>> >>>>>And so on. So I have over 6 hours of idle time, and the next biggest chunk of >>>>>CPU usage time was by Internet Explorer, of a whole 2 minutes. That means there >>>>>is 99.5% of the CPU time that could have been used by a chess program. So the >>>>>question is whether or not a 0.5% increase in speed is going to mean >>>>>"significantly better" results. I think not.
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