The race is on to produce four-core processors for PCs. Intel, which is readying a bevy of dual-core chips for release in systems in the next month, is already plotting a move to quad cores, which some reports have said could come as soon as early 2007. AMD has already discussed a plan to begin offering a family of four-core chips in 2007, whereas Intel has only hinted about a four- core server chip thus far.
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Member since:> I agree that most of the processes are asleep. The
> point I am trying to make is that if you are running
> one resource hungry process, there are still a LOT of
> other processes running on the system and each one of
> them requires CPU time at some point or another.
Yes, at some point or another. Let's say you have one resource hungry process that keeps one cpu busy, and a bunch of little processes that keep the second cpu busy 1/10 of the time. If the big process properly supported multiprocessing, both cpus would be busy all the time (minus communication overhead, which approaches zero if the multiprocessing support is "done right").
- Morin
Member since:I agree, and will push the point further. Obviously, the era of routinely coded intrisically multithreaded applications has not yet arrived. Yet even with conventional applications coded for single CPU environments, there are very clear performance improvements and advantages to a garden variety SMP environment which extends also to the newer multicore CPUs.
I've been running this sort of thing on my desktop for years, long before it was routinely fashionable. I've found that a machine running say two SMP 1GHz CPUs is at least as subjectively fast as an otherwise identical system running a single 2GHz CPU of the same family and generation. Further, I've usually spent no more, and ofter less for the SMP system using this stategy.
For most desktop applications, the feel of the system speed is based on the latency at the mouse-keyboard-screen to a user action. Once i86 CPUs passed 700MHz point, latency for most desktop users became a faily insignificant point. Most users see the latency increase and the system feel sluggish then several applications are competing for CPU cycles concurrently. With an SMP environment, one applications can continue to feel responsive on one CPU while another compute intensive application fully consumes the resources of the second CPU in the background (e.g. rasterization of a vector graphic file for printing). One CPU even at twice the clock speed would feel substantially slower.
For example, my main system on my desktop is an old Sun Ultra 60 with two 450 MHz 64bit SPARC CPUs, 1.5 GHz memory, and dual video cards on the UPA dedicated video bus in dual head config. It is an aging machine by any definition, but it does not feel slow, and remains very useful as a desktop. Aside from the SMP advantages, the video and memory buses are fast and wide. The CPU speed ultimately determines the absolute system throughput which by today's standards are very modest, but for routine desktop tasks, this is not apparent to the user.
Most of the "speed" issues were previously with realtime graphical ( e.g. gaming ) applications that often were more bound by the memory bandwidth and speed of graphics subsystems than the system CPU. Now, with very high memory and graphics bus bandwidth and very fast graphics subsystems, the CPU is usually the determinant of system speed for these applications. Until the gaming programmers and others what use system resources in "Von Neumann" single thread style are developing for multithread multiCPU systems, systems with single system CPUs at maximum clock speed are going to provide them the best performance.
Member since:
2005-10-22
I agree that most of the processes are asleep. The point I am trying to make is that if you are running one resource hungry process, there are still a LOT of other processes running on the system and each one of them requires CPU time at some point or another.