4 Replies Latest reply: Oct 28, 2009 1:30 PM by Chris Cox RSS

    CS3 multiprocessor usage not above 50%

    coinup001 Community Member

      I have :-

       

      windows XP64bit

      6Gb ram

      pentium 4 3.6 dual core

       

      when running under heavy usage my processor usage dosn't go above 50% i thought it should??

       

      is there a fix ?? i have changed processor scheduling to programs/background services no change.

       


      thanks.

        • 1. Re: CS3 multiprocessor usage not above 50%
          Chris Cox Adobe Employee

          No, there is no fix, because there is no bug.

           

          The amount of multiprocessor usage will depend on the size of the image (small images won't take long to finish), the exact operation (some can use all processors, some can use only 1, some can use Hyperthreading and some can't), the parameters involved (larger calculations take longer, see more benefit), etc.

           

          Try running Radial Blur or Median on a large image, you'll see plenty of CPU usage.

           

          Photoshop is always using as much processor power as it can for the task at hand.

          • 2. Re: CS3 multiprocessor usage not above 50%
            klsteven-vBdprK Community Member

            Chris,

            that`s a point that interested me also. Lets say the operation can handle all of my four cores and the usage goes up only to lets say 30%, could this mean that my RAM or memory bandwidth is the bottleneck? If so, do the new Core I7 CPUs "solve" that problem?

            • 3. Re: CS3 multiprocessor usage not above 50%
              Mylenium CommunityMVP

              Lets say the operation can handle all of my four cores and the usage goes up only to lets say 30%, could this mean that my RAM or memory bandwidth is the bottleneck?

               

              There is most certainly no bottleneck. Generally you should get away from thinking in these absolute performance terms and contrary to what you believe, the figures would not change with a different modern processor, most likely. Simply consider, that most processors have much more juice than is required for most normal operations and that just like the program's internal routines, the operating system's resource management as well as management features in the chips themselves control the actual processor usage as well. Additionally, do not forget that your task manager only samples ever n cycles, not every clock cycle. Many times it will miss the few nanaoseconds where the processor really peaked and the graph realyl is just an avarage.

               

              Mylenium

              • 4. Re: CS3 multiprocessor usage not above 50%
                Chris Cox Adobe Employee

                It could mean that RAM, disk, or some part of the OS is limiting speed (cache flushing in certain APIs will hose all processes).

                It could mean that the CPU cache or some other process is limiting speed (esp. those causing bad cache activity, or a lot of bus activity).

                It could mean that the image is so small that overhead dominates the total time instead of calculation. (and "small" is relative)

                It could mean that the OS is reporting the CPU activity on such a coarse sampling that you never see the real performance (you'd have to sample every tenth of a second or better to really see what's going on).  Simplistic example: 100% CPU for one second could easily be reported as 50% CPU for 2 seconds if sampled at the wrong time.

                Etc.