Yeah, of course. I was obviously not suggesting that to be actually done. I was just wondering how comparable to multi-core CPU's such a design decision would be.
I know all that, that's why I said "aside from the fact that you'd need a powerful CPU to get the same result with 25% of its time slices as with one core of a quad-core CPU".
"If you run an application that uses 100% of only one of the cores, your computer will not hang as there are other cores it can use."
If you run an application that uses 100% of only one "virtual core", your computer will not hang either, that's the point of my previous comment. OK, there you're only using 25% of the power of your single-core CPU, but after all, when using 100% of a core out of four-cores, you're still using 25% of the power of your CPU.
So why is one acceptable and not the other? For scale reasons? (understand, using one core of a recent four core CPU gives u a good performance, as using 25% of a recent single core CPU gives you a poor performance, so the difference is in a way only a matter of scale)
"The main mistake I think people are making is the idea of having each thread do something different"
Totally agree. I once read a comment by a guy who was talking about a 8-core gaming system, and suggesting that one would be dedicated to graphics, one to the AI, one to sound, one to controlling the controllers, lol, some stupid crap like that. If you're gonna use a whole core just for controlling a keyboard or a gamepad, needless to say that you're a fool.
Of course they need to be put to contribution in a way that all the available power is used when needed. Which makes me think, let's say you run a CPU hungry application, couldn't by some way the OS cut the work to be done between each core so it would run concurrently on many cores without the application program to have to modify anything, just having the OS to deal with it?
I realize that the main problem with my question is, if your application is doing serial processing (for example basing it's next computation on the result of the previous one) it's not gonna be easy to make it work concurrently on several cores, but to a more or less small extent, couldn't something be done about the OS so it could make some applications written for a single core take advantage of multiple cores?
"you'll at least be able to fire up a shell (or the Task Manager) and find out why something's so slow."
That's why I been wondering for years, why not just prevent something from using 100% of the CPU? I mean, if we let a process only take up to let's say 99% of the CPU, we'd still have a system reactive enough to get to the task manager and eventually put and end to the process that would otherwise make anything else so slow that you'd have to reboot. It's not even about priority, just about preventing a process from using 100%, and depriving it from a non-significant processing time, but that would be significiant for the other tasks.
"This makes for a snappier system because the UI threads aren't competing for CPU time on a clogged CPU."
Yeah, I imagine it to be a nice advantage, but it makes think of two things. Firstly, why not use all the other cores instead of one? And then, if you only need one core on a multi-core CPU, why won't you need a limited percentage of a one-core CPU for each thread so it acts the same?
Maybe what I mean is not clear, so imagine a quad-core CPU. Your threads can use each core etc, etc.. On a single-core, why don't you "cut" your CPU into 4 "virtual cores" so for example one thread that would act like it's only using one "virtual core" would actually be using 25% of the CPU time slices?
I'm not proposing realizing virtual cores tho, it would come back to having the disadvantage of having multiple cores and the power of only one CPU, but as a purely theorical question i'd like to know what it changes (aside from the fact that you'd need a powerful CPU to get the same result with 25% of its time slices as with one core of a quad-core CPU).
So I got one question that I've been wondering since the Dual G4's appeared, why does it seem important to dedicate a core to a task and another to another over making run both on one core the way we know it (with interrupts so each gets its fair share of time)? Of course the sum of the power you can get to with let's say two cores is surely more than what you can get with only one, but is this the only reason?
Or is there some reason that would make having two 1 GHz cores better than one 2 Ghz core?
"There have been many "the end is near" predictions over the decades, and none have come true"
Well as you surely know, that's pretty much the magic of the Moore law. No matter what happens, CPU's will improve in performance (although the law really talk about transistors), period.
However, I don't know about you, but that multi-core thing gives me the feeling that they are getting into this because they're having a though time getting over 4 Ghz. As if, because they hardly can improve the CPU's the way they always used, they needed another solution to go on further. I mean look, new CPU's still come out with barely 2 GHz. Back about 10 years ago, you were getting from 66 Mhz to 200 Mhz in no time.
I wasn't talking about the software benefits from more Mhz. I was talking about benefiting, understand, being able to use, those new cores, compared to being able to use the new MHz, back then.
The point was that, if your computer had twice as much MHz, basically, you could make let's say twice as many multiplications in as many time. But if you have a quad-core CPU, given the same amount of GHz, you will only be able to make 4 time as many multiplications if your software is written for using those 4 cores, otherwise, you're fucked.
Nothing to do with whether in your everyday use you benefit from more power or not.
Build a fence? That's what surprised me when I went to the USA. People have nothing to separates their yards. Here, I have a 6-foot hedge that delimitates the border of my yard
That one game depresses me. You are there, wandering the emptiness of space with your little space ship with its ridiculous proton laser gun that wouldn't move an asteroid from its orbit, trying to avoid any fights with the other ships, that are all bigger and better armed than you, to strive through hostile systems to deliver your 10 tons of food that you'll sell 70% more than you bought them, a stop at the station, fullfil your 5-shot hyperspace travel drive thing with fuel, look for some new *exciting missions*, by a map of the neighbourhood, and then deliver your ten passengers to a nearby system, until you get stuck without any hyperspace travel possible in some system only populated by wandering asteroids, unless you buy that expensive energy-reloader that will let you travel back to the nearest inhabited system, provided that you wait for about 2 minutes for you to load, and there you are going again for selecting a system you want to pass by and reload your hyperspace driver fuel thing, slow down, select the station to dock yourself and, and then push the gas again to get far enough to start the hyperspace travel, etc, etc, etc...
What's the point of this game anyway? To manage to get yourself a bigger second-hand ship after you transported 56,730 tons of merchandise through the galaxy in 536 hyperspace jumps?
Nice video. The cops part reminds me how easy it is to fool the cops into doing some stupid stuff. Worse is, get under a bridge (or nearly under), have some wanted level, and after a few seconds you could sing "it's raining cops, hallelujah!". Other than that, it's quite fun to have the cops to follow you close, and have them fail where you succeed, like for example, jump, for example above a river. Good way to get rid of them, atlhough sitting next to the water is a good one too.
By the way, are all these PCJ-600 specific Vice City stunts that consist in hitting something, spinning by a few thousand degrees and land on top of some building 50 feet higher still possible in GTA San Andreas? Because it seems to me like that side of the physics is more realistic in SA than Vice City.
"Word on my 233MHz G3 worked as well as it did on 800MHz G4 as it does on my 2x2GHz G5 and as well as it does on my 3.2GHz P4."
What you just said reminds me of something I read before, it was something like "Computers in 93 used to run Word as fast as on "I really think in the "megahertz" race we didn't really enjoy the benefits in all areas of software. vi, emacs, text editor x don't really benifit from 3GHz over 333MHz."
Suuure. It didn't benefit much for NetHack neither, but what kind of improvement can you expect from vi that is not mainly design decisions or stuff like that?
vi now can only get as good as it could have got ten years ago because it meets more than the requirements it needs to do anything it can do. But many areas of software can't say they met more than they need, and that's obviously why computers need to go faster for some type of applications to improve.
I fail to see your point anyways, is it that computers don't need to go faster, just because we can run vi or Word fast? Are that type of applications all you need, or do you also use more needy applications like for example a web browser that would have runned more painfully on your 233 Mhz G3?
"I hope this gives an impetus to improve multi-CPU software performance."
Yes, but there is the problem. With the Gigahertz race, you were sure to be able to enjoy the benefit. With multiple cores, you need software able to use these cores, am I wrong (I'm not really sure of what I'm talking about)? And so far we can't always fully exploit these multiple cores, am I wrong?
Yeah, I feel you, and I don't think that guy has any calculation to back his claim that the clock gets slown down by energy conservation.
Hard indeed to throw out 100 years of science for a guy who claims that there can't be such a thing as a space-dimension because of dt/dt=1. Actually I wrote the guy a mail, may someone correct me if I made some major mistake in it.
"I read with interest my pages of your site, however, your main claim about time is quite disturbing. Basically, you claim that we cannot travel in in time-dimension because dt/dt=1. But to me, and to alot of Slashdotters, dt/dt=1 only shows that you can only measure the time to go at a constant rate, for example, you will always measure a second to last one second.
It doesn't prevent time dilation however. The self-reference of dt/dt doesn't prove that time travel isn't possible, it only shows that you weren't able to spot what alot of people out here could spot, that it means that time can only be, locally, measured at a constant rate. But if you quit making self-referring equations, you'll see that a GPS will have a time ratio of 1 if only based on local measures, for example, dt gps/dt gps, but a different one if you compare it to other measurement, for example dt gps/dt earth.
Take a GPS satellite, and an observer on earth. Both synchronize their time to 0. When the observer's clock reaches let's say 60 seconds (dt earth), the GPS clock reached only let's say, 59 seconds (dt gps). This means that the GPS satellite traveled 59 seconds in 60 seconds, in other words, 0.983 s.s^-1.
You claimed that the unit would cancel itself, well it can if you want (although s.s^-1 makes sence to me, provided that you remember that the first s refers to other seconds than the second s) you would obtain a time rate ratio of 0.983, with respect to the observer's time. I don't see where's the non-sense in it, and therefore, I claim that time-travel, even if only in one direction, is possible. "
Exactly. The worse is that I got fooled for a minute. That's what happens when you sleep barely 3 hours. Too bad this article's main point is so non-sensical that anybody could spot it, it's got interesting ideas anyways, well, ideas that only make me more confused when it comes to making myself an idea of what space and time really are.
Wait, aren't we talking at the speed at which we "travel" into time? I think the meaning of dt/dt is to say that time can only appear to go at always the same rate
"Also, I'd be interested in what the author's view on the speed of light (if there really is such a thing!) and *experimental* evidence for relativity. This is important, because if the author is right, we've done GPS all wrong! We're correcting those clocks for nothing!"
"Time does not dilate for the simple reason that time, by definition, cannot change. The slowing of clocks is more likely due to energy conservation principles that come into play when a huge number of particles are interacting locally."
"Again, clocks run slower, not because time dilates, but because their internal processes slow down due to energy conservation principles. "Time dilation" = process slowdown. There is no causal link between the two. They are equivalent."
Slashdot Mirror
Yeah, of course. I was obviously not suggesting that to be actually done. I was just wondering how comparable to multi-core CPU's such a design decision would be.
;-)
"If you run an application that uses 100% of only one of the cores, your computer will not hang as there are other cores it can use."
If you run an application that uses 100% of only one "virtual core", your computer will not hang either, that's the point of my previous comment. OK, there you're only using 25% of the power of your single-core CPU, but after all, when using 100% of a core out of four-cores, you're still using 25% of the power of your CPU.
So why is one acceptable and not the other? For scale reasons? (understand, using one core of a recent four core CPU gives u a good performance, as using 25% of a recent single core CPU gives you a poor performance, so the difference is in a way only a matter of scale)
Totally agree. I once read a comment by a guy who was talking about a 8-core gaming system, and suggesting that one would be dedicated to graphics, one to the AI, one to sound, one to controlling the controllers, lol, some stupid crap like that. If you're gonna use a whole core just for controlling a keyboard or a gamepad, needless to say that you're a fool.
Of course they need to be put to contribution in a way that all the available power is used when needed. Which makes me think, let's say you run a CPU hungry application, couldn't by some way the OS cut the work to be done between each core so it would run concurrently on many cores without the application program to have to modify anything, just having the OS to deal with it?
I realize that the main problem with my question is, if your application is doing serial processing (for example basing it's next computation on the result of the previous one) it's not gonna be easy to make it work concurrently on several cores, but to a more or less small extent, couldn't something be done about the OS so it could make some applications written for a single core take advantage of multiple cores?
That's why I been wondering for years, why not just prevent something from using 100% of the CPU? I mean, if we let a process only take up to let's say 99% of the CPU, we'd still have a system reactive enough to get to the task manager and eventually put and end to the process that would otherwise make anything else so slow that you'd have to reboot. It's not even about priority, just about preventing a process from using 100%, and depriving it from a non-significant processing time, but that would be significiant for the other tasks.
Does switching from a task to another sums up to a significant percentage of CPU time slices?
Ever heard about video games? yet it's just an example
Yeah, I imagine it to be a nice advantage, but it makes think of two things. Firstly, why not use all the other cores instead of one? And then, if you only need one core on a multi-core CPU, why won't you need a limited percentage of a one-core CPU for each thread so it acts the same?
Maybe what I mean is not clear, so imagine a quad-core CPU. Your threads can use each core etc, etc.. On a single-core, why don't you "cut" your CPU into 4 "virtual cores" so for example one thread that would act like it's only using one "virtual core" would actually be using 25% of the CPU time slices?
I'm not proposing realizing virtual cores tho, it would come back to having the disadvantage of having multiple cores and the power of only one CPU, but as a purely theorical question i'd like to know what it changes (aside from the fact that you'd need a powerful CPU to get the same result with 25% of its time slices as with one core of a quad-core CPU).
Or is there some reason that would make having two 1 GHz cores better than one 2 Ghz core?
Well as you surely know, that's pretty much the magic of the Moore law. No matter what happens, CPU's will improve in performance (although the law really talk about transistors), period.
However, I don't know about you, but that multi-core thing gives me the feeling that they are getting into this because they're having a though time getting over 4 Ghz. As if, because they hardly can improve the CPU's the way they always used, they needed another solution to go on further. I mean look, new CPU's still come out with barely 2 GHz. Back about 10 years ago, you were getting from 66 Mhz to 200 Mhz in no time.
The point was that, if your computer had twice as much MHz, basically, you could make let's say twice as many multiplications in as many time. But if you have a quad-core CPU, given the same amount of GHz, you will only be able to make 4 time as many multiplications if your software is written for using those 4 cores, otherwise, you're fucked.
Nothing to do with whether in your everyday use you benefit from more power or not.
Build a fence? That's what surprised me when I went to the USA. People have nothing to separates their yards. Here, I have a 6-foot hedge that delimitates the border of my yard
What's the point of this game anyway? To manage to get yourself a bigger second-hand ship after you transported 56,730 tons of merchandise through the galaxy in 536 hyperspace jumps?
By the way, are all these PCJ-600 specific Vice City stunts that consist in hitting something, spinning by a few thousand degrees and land on top of some building 50 feet higher still possible in GTA San Andreas? Because it seems to me like that side of the physics is more realistic in SA than Vice City.
What.. are.. you.. talking.. about?
What you just said reminds me of something I read before, it was something like "Computers in 93 used to run Word as fast as on "I really think in the "megahertz" race we didn't really enjoy the benefits in all areas of software. vi, emacs, text editor x don't really benifit from 3GHz over 333MHz."
Suuure. It didn't benefit much for NetHack neither, but what kind of improvement can you expect from vi that is not mainly design decisions or stuff like that?
vi now can only get as good as it could have got ten years ago because it meets more than the requirements it needs to do anything it can do. But many areas of software can't say they met more than they need, and that's obviously why computers need to go faster for some type of applications to improve.
I fail to see your point anyways, is it that computers don't need to go faster, just because we can run vi or Word fast? Are that type of applications all you need, or do you also use more needy applications like for example a web browser that would have runned more painfully on your 233 Mhz G3?
And look whether my post is modded insightful or whoring as well.
Yes, but there is the problem. With the Gigahertz race, you were sure to be able to enjoy the benefit. With multiple cores, you need software able to use these cores, am I wrong (I'm not really sure of what I'm talking about)? And so far we can't always fully exploit these multiple cores, am I wrong?
Say bye to the race to the Gigahertz. Say hello to the race to the core count
Tell George Bush, Michael Crichton and half of americans...
Wait, we already do that! Welcome to the future, bloke!
Hard indeed to throw out 100 years of science for a guy who claims that there can't be such a thing as a space-dimension because of dt/dt=1. Actually I wrote the guy a mail, may someone correct me if I made some major mistake in it.
"I read with interest my pages of your site, however, your main claim about time is quite disturbing. Basically, you claim that we cannot travel in in time-dimension because dt/dt=1. But to me, and to alot of Slashdotters, dt/dt=1 only shows that you can only measure the time to go at a constant rate, for example, you will always measure a second to last one second.
It doesn't prevent time dilation however. The self-reference of dt/dt doesn't prove that time travel isn't possible, it only shows that you weren't able to spot what alot of people out here could spot, that it means that time can only be, locally, measured at a constant rate. But if you quit making self-referring equations, you'll see that a GPS will have a time ratio of 1 if only based on local measures, for example, dt gps/dt gps, but a different one if you compare it to other measurement, for example dt gps/dt earth.
Take a GPS satellite, and an observer on earth. Both synchronize their time to 0. When the observer's clock reaches let's say 60 seconds (dt earth), the GPS clock reached only let's say, 59 seconds (dt gps). This means that the GPS satellite traveled 59 seconds in 60 seconds, in other words, 0.983 s.s^-1.
You claimed that the unit would cancel itself, well it can if you want (although s.s^-1 makes sence to me, provided that you remember that the first s refers to other seconds than the second s) you would obtain a time rate ratio of 0.983, with respect to the observer's time. I don't see where's the non-sense in it, and therefore, I claim that time-travel, even if only in one direction, is possible. "
Exactly. The worse is that I got fooled for a minute. That's what happens when you sleep barely 3 hours. Too bad this article's main point is so non-sensical that anybody could spot it, it's got interesting ideas anyways, well, ideas that only make me more confused when it comes to making myself an idea of what space and time really are.
Wait, aren't we talking at the speed at which we "travel" into time? I think the meaning of dt/dt is to say that time can only appear to go at always the same rate
It's simply on another page of the website. http://www.rebelscience.org/Crackpots/devil.htm
"Time does not dilate for the simple reason that time, by definition, cannot change. The slowing of clocks is more likely due to energy conservation principles that come into play when a huge number of particles are interacting locally."
"Again, clocks run slower, not because time dilates, but because their internal processes slow down due to energy conservation principles. "Time dilation" = process slowdown. There is no causal link between the two. They are equivalent."