<br><br><b><i>Rick Moynihan <rick.moynihan@gmail.com></i></b> wrote:<blockquote class="replbq" style="border-left: 2px solid rgb(16, 16, 255); margin-left: 5px; padding-left: 5px;"> 2008/4/25 Andrew Clayton <andrew@digital-domain.net>:<br>><br>> On Fri, 25 Apr 2008 11:38:19 +0100, Rick Moynihan wrote:<br>><br>> > 2008/4/25 Andrew Clayton <andrew@digital-domain.net>:<br>> > > On Thu, 24 Apr 2008 22:54:29 +0100 (BST), Lee Hughes wrote:<br>> > ><br>> > > > yeah, but will the software (os/app's) take advantage of all that<br>> > > > threading capability?<br>> > ><br>> > > I'll use the terms cores and cpu's interchangeably below..<br>> > ><br>> > > Of course. Linux itself is quite capable of dealing with many<br>> > > cpu's, with support for 4096 cpu's currently being worked on for<br>> > > merging from the folks at SGI.<br>> > ><br>>
> > You want real world examples,<br>> > ><br>> > > Compiling is an obvious one with make supporting parallel compiling<br>> > > natively, e.g make -j <num cpu="" s="" +="" 1=""><br>> > ><br>> > > If you use a source based distribution, you'll like many cores...<br>> > ><br>> > > Saw a recent reference to an IBM machine that does 3K/sec (that's 3<br>> > > kernel builds a second)<br>> > ><br>> > > Grip supports multiple cpu's for encoding audio.<br>> > ><br>> > > I'm sure games will start supporting multiple cores, in fact IIRC<br>> > > some version of quake does/did.<br>> > ><br>> > > Any java app you use...<br>> > ><br>> > > And just having the capacity that comes from having multiple cores,<br>> > > video encoding not interfering with your compilation for example.<br>> >
><br>> > > That heavy javascript site causing firefox to hammer one of your<br>> > > cores.<br>> > ><br>> > > So yeah, Linux has been ready for this for a long time and as<br>> > > multiple cores become more prevalent, I'm sure more apps will be<br>> > > written specifically to take advantage.<br>> ><br>> > This is all true, but with the current state of hardware (at least<br>> > under x86) I suspect that simply adding more CPUs & cores leads<br>> > diminishing returns, due to problems with shared memory; i.e. cache<br>> > and memory flushes under the hood. Sure an 8/16 core machine sounds<br>> > great, but I'm not sure if I could ever keep all the cores busy during<br>> > my normal workload.<br>><br>> Yeah, It can depend on what your doing, long running cpu<br>> intensive jobs probably make the most efficient use of multiple<br>>
cores/cpu's.<br>><br>> And I was just reading this thread,<br>> http://www.ussg.iu.edu/hypermail/linux/kernel/0804.2/3300.html<br>><br>> "I have 128 cpus, that's 128 grabs of that spinlock every quantum. My<br>> next system I'm getting will have 256 cpus."<br><br>Am I right in reading that thread as illustrating the problems of<br>shared memory?<br><br>The quote you pasted taken out of threads surrounding context seems to<br>imply something like "I'm happy with my 128 CPU's blocking on memory<br>writes, so I'm going to waste lots of money on 256 CPU's next time!!!"<br> When I think it's really just saying, "this is really going to bite<br>when we have 256 CPUs!"<br><br>> > A single quad-core CPU where each core screams speed, seems like a<br>> > better investment than going for 2 processors. The question is<br>><br>> Yes, a quad core is likely better than 2 single core processors.<br>><br>><br>><br>hmm, interesting stuff
indeed....<br><br>So you need to analyse your current workload, identify your bottlenecks, you may be I/O bound for instance..move your compilation environment onto a ram disk, and see what performance you get.<br><br>I'd still say freezing you cpu and over clocking it the way to go!!!! ;-)<br>maxium speed!!! :-).... <br><br><br><br><br><br><br><br><br><br><br><br><br><br><br>> _______________________________________________<br>> dundee GNU/Linux Users Group mailing list<br>> dundee@lists.lug.org.uk http://dundee.lug.org.uk<br>> https://mailman.lug.org.uk/mailman/listinfo/dundee<br>> Chat on IRC, #tlug on dundee.lug.org.uk<br>><br><br><br><br>-- <br>Rick Moynihan<br>rick.moynihan@gmail.com<br>http://sourcesmouth.co.uk/blog/<br><br>_______________________________________________<br>dundee GNU/Linux Users Group mailing list<br>dundee@lists.lug.org.uk http://dundee.lug.org.uk<br>https://mailman.lug.org.uk/mailman/listinfo/dundee<br>Chat on IRC, #tlug
on dundee.lug.org.uk<br></num></andrew@digital-domain.net></andrew@digital-domain.net></blockquote><br><p> 
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