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OT: Nostalgia - Was "PTgui -- why doesnt it just use RAM?"

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  • Charlie Hubbard
    ... Yes it still amazes me how cheap computer equipment has become. There seems to be no end. I m a bit older than you, I think. I got my first computer
    Message 1 of 19 , Dec 1, 2007
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      > here in Brazil RAM is getting very cheap everyday too
      > I remember the first MAC I use in the 90's and the price was 1 dolar
      > for each 1mb :-(

      Yes it still amazes me how cheap computer equipment has become. There
      seems to be no end. I'm a bit older than you, I think. I got my first
      computer around 1979 or 1980. RAM cost 200 dollars (US) for 16 kilobytes
      (but dropped to $100 for 16kB before the thing was completely obsolete).
      And prices have been plummeting ever since. I remember when the first
      1GB hard disks came out. They were big, noisy, power hungry, and very
      expensive. I remember thinking at the time "How could I ever possibly
      use up an entire gigabyte?!" I knew a guy who had one. He had it
      partitioned into 16 or so logical drives to keep the file system's block
      size reasonably small. Today it's pretty routine to have single files
      larger than 1GB. I remember getting a 3GB external SCSI drive out at
      work in the early 90's. We had it sitting on a typing table next to the
      computer. It was a monster. The table actually shook when the drive
      was spinning up. Today I carry an 8GB thumb drive in my pocket. Who
      can forget Bill Gates' 1983 quote "Nobody will ever need more than 640
      kB of RAM." Today even modest computers have 1- or 2,000 times that
      much RAM. I remember when 640x480 reigned supreme and JPGs were
      extremely annoying because it took SO DAMN LONG for them to decode.
      Times have changed. It will be interesting to see what the future holds.
    • panotools@360image.de
      Hi Matt, ... 5 hours seems a bit excessive. Although, you work on a laptop which have low speed hdd usually. On your speedtest results you mention an external
      Message 2 of 19 , Dec 1, 2007
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        Hi Matt,
        >
        >
        > What I'm fairly certain of is that in the 5 hours it takes my dual core
        > 2GHz machine (2:30 minutes on Milko's speedtest) to stitch a 16bit
        > 11,000x5500 image, my CPU reads 5-10% most of the time and my disks are
        > not being accessed much of this time (and could write 1GB a few hundred
        > times in that time anyway, if that were truly the bottleneck).
        >
        5 hours seems a bit excessive. Although, you work on a laptop which have
        low speed hdd usually.
        On your speedtest results you mention an external 500gig drive connected
        with USB2.
        Are you hosting the panorama project files and sources on that drive?
        And where are you sending your temp files to?

        Cheers, Milko
      • matt_nolan_uaf
        Milko, I guess I need to do some further controlled tests, but as you know my machine performed your speed test at 2.5 minutes, which is comparable to others.
        Message 3 of 19 , Dec 1, 2007
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          Milko,

          I guess I need to do some further controlled tests, but as you know
          my machine performed your speed test at 2.5 minutes, which is
          comparable to others. Using the same configuration, a 11,000 x 5,500
          pix pano (7 images at 70 MB each) at 8 bit takes about 30-45 minutes
          to process (need to check). Going to 16 bit more than doubles it to
          5 hours or more (dont know, I always kill it first). But there could
          easily be something buggering up my system that has nothing to do
          with PTgui itself. Glad to hear that others are doing this much
          faster. Maybe we need another speed test -- one with a large file
          size, as there could be different issues associated with this?

          To all, yes, my laptop has tons of stuff loaded on it, and I have
          seen the light of buying a dedicated stitching box. But in
          researching the fastest hard drives, I read about hard disks built
          from RAM that plug into a standard SATA slot. These are not flash
          disks, but literally using RAM and I began thinking, why is there any
          disk access at all for a project that can fit into real RAM anyway?
          I'm still not sure why.

          In case others are interested, visit this page to learn about the
          apparent benefits of setting up two such RAM disks in RAID 0.
          http://www.tomshardware.com/2005/12/05/hyperos_dram_hard_drive_on_the_
          block/page6.html The big winner seems to be iRAM, which you can buy
          for about $140 for the card and up to 4 GB of cheap slow RAM (buying
          fast RAM doesnt help, because the cheap stuff is already maxing out
          the 1.5 GB/s SATA channel, and there is no 3.0GB/s disk yet
          apparently).

          For spherical fisheye stitching, where project needs are never higher
          than 3 or 4 GB max of scratch space, this could be the silver bullet
          that could get Milko's test down to near zero. These disks in RAID 0
          are apparently hundreds to thousands of times faster than Raptors or
          SAS!

          Another trick I've read about is called quarter stroking your disk.
          Apparently you can create a partition on a 7500 RPM disk such that
          the partition is only using the inner portion of the disk, so that
          the arm doesnt move so far. Doing this is apparently faster than
          using a 15k SAS disk, and much cheaper, and plus you still get the
          slow part of the disk to use for storage.

          So I'm beginning to think of a system like this:
          - XP 64 bit loaded onto a 16 GB flash disk
          - RAID 0 iRAM 2 GB disks for stitching fisheye sphericals
          - RAID 0 750 GB disks SATA II quarter stroked to provide about 375 GB
          of fast scratch space for gigapixel panos, with the rest (about 1TB)
          for storage.
          - eSATA external disks for backup

          My other constraint is that I work from home and live off the
          electrical grid. So these flash and RAM disks make great sense for
          me, as thinking of a computer with a 500W power supply give me the
          shudders...


          -Matt




          --- In PanoToolsNG@yahoogroups.com, "panotools@..." <panotools@...>
          wrote:
          >
          > Hi Matt,
          > >
          > >
          > > What I'm fairly certain of is that in the 5 hours it takes my
          dual core
          > > 2GHz machine (2:30 minutes on Milko's speedtest) to stitch a 16bit
          > > 11,000x5500 image, my CPU reads 5-10% most of the time and my
          disks are
          > > not being accessed much of this time (and could write 1GB a few
          hundred
          > > times in that time anyway, if that were truly the bottleneck).
          > >
          > 5 hours seems a bit excessive. Although, you work on a laptop which
          have
          > low speed hdd usually.
          > On your speedtest results you mention an external 500gig drive
          connected
          > with USB2.
          > Are you hosting the panorama project files and sources on that
          drive?
          > And where are you sending your temp files to?
          >
          > Cheers, Milko
          >
        • matt_nolan_uaf
          I created a RAM disk using http://www.ramdisk.tk/, changed my scratch disk and write disk to the ram disk, and ran Milko s speed test and got exactly the same
          Message 4 of 19 , Dec 2, 2007
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            I created a RAM disk using http://www.ramdisk.tk/, changed my scratch
            disk and write disk to the ram disk, and ran Milko's speed test and got
            exactly the same results -- 2 minutes 30 seconds. Wierd. How could it
            not be incredibly faster? My dual CPUs ran at 50%, with one near 100%
            and the other near idle; I checked the affinity for PTgui was set to
            both.

            -Matt


            --- In PanoToolsNG@yahoogroups.com, Bruno Postle <bruno@...> wrote:
            >
            > On Sat 01-Dec-2007 at 22:28 -0000, matt_nolan_uaf wrote:
            > > To create a hi-res spherical, PTgui says 7 tiffs at 70MB each
            > > requires about 1GB of scratch disk -- if I have 4 GB of RAM, why
            > > does it need a disk at all except to save the final image?
            > > Wouldn't doing everything in RAM dramatically speed things up,
            > > especially since disk I/O seems to be the bottleneck?
            >
            > Good point, try setting up a 2GiB RAM disk for the scratch data and
            > see if that makes an improvement.
            >
            > --
            > Bruno
            >
          • Joost Nieuwenhuijse
            This is because PTGui was already using RAM.. PTGui stores temporary data in temp files, but due to the OS s file system caching, the files never really get
            Message 5 of 19 , Dec 2, 2007
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              This is because PTGui was already using RAM..

              PTGui stores temporary data in temp files, but due to the OS's file
              system caching, the files never really get written to disk but instead
              they are cached in RAM. Only for large panoramas the OS will not have
              enough cache memory and that's when the temporary files actually start
              being written to disk.

              This also means that PTGui should use all available RAM as long as the
              OS is not doing anything else.

              These 'stitching speed' questions are always difficult to answer since
              there are so many factors that influence the speed.

              Joost


              matt_nolan_uaf wrote:
              > I created a RAM disk using http://www.ramdisk.tk/, changed my scratch
              > disk and write disk to the ram disk, and ran Milko's speed test and got
              > exactly the same results -- 2 minutes 30 seconds. Wierd. How could it
              > not be incredibly faster? My dual CPUs ran at 50%, with one near 100%
              > and the other near idle; I checked the affinity for PTgui was set to
              > both.
              >
              > -Matt
              >
              >
              > --- In PanoToolsNG@yahoogroups.com, Bruno Postle <bruno@...> wrote:
              >> On Sat 01-Dec-2007 at 22:28 -0000, matt_nolan_uaf wrote:
              >>> To create a hi-res spherical, PTgui says 7 tiffs at 70MB each
              >>> requires about 1GB of scratch disk -- if I have 4 GB of RAM, why
              >>> does it need a disk at all except to save the final image?
              >>> Wouldn't doing everything in RAM dramatically speed things up,
              >>> especially since disk I/O seems to be the bottleneck?
              >> Good point, try setting up a 2GiB RAM disk for the scratch data and
              >> see if that makes an improvement.
              >>
              >> --
              >> Bruno
              >>
              >
              >
              >
              >
            • Pat Swovelin
              ... Is that also a good number for WinXP with 4GB RAM and the 3GB switch flipped? ... Pat Swovelin Cool Guy @ Large
              Message 6 of 19 , Dec 2, 2007
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                On 12/1/2007 3:44 PM, Hans Nyberg rambled on about ...:
                > --- In PanoToolsNG@yahoogroups.com, "AYRTON - avi" <avi@...> wrote:
                >> On 12/1/07, Hans Nyberg <hans@...> wrote:
                >>
                >>> The 11400x5700 16bit takes 31 minutes using PTguiWarp + Ptgui Blend.
                >>>
                >>> Using PTGuiWarp + Enblend with 3 GB Ram applied I get down to 19.20
                >>> minutes.
                >> Sorry I could NOT figure out HOW to aplly more RAM when using Enblend ???
                >> Pls some directions will be appreciatted :-)
                >> Thanks
                >
                > In PTGui Preferences/Plugins write: -m 3000 in the command line parameters

                Is that also a good number for WinXP with 4GB RAM and the 3GB switch
                flipped?

                > If your mac and Enblend 3.0 behaves the same as mine enblend will
                > crash after a while if
                > you try to apply 3600 or more.
                > How much Ram did you get?
                > I just found out that I can update my G5 with 4 gb and get 8 in all
                > for just $130.
                > I guess I paid 4 btimes as much at least for the 4 GB I got when I
                > bought the G5.
                >
                > Hans




                Pat Swovelin
                Cool Guy @ Large
              • matt_nolan_uaf
                This is because PTGui was already using RAM.. ... instead ... have ... start ... I guess I m missing something easy and fundamental. For fisheye sperhical
                Message 7 of 19 , Dec 4, 2007
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                  This is because PTGui was already using RAM..
                  >
                  > PTGui stores temporary data in temp files, but due to the OS's file
                  > system caching, the files never really get written to disk but
                  instead
                  > they are cached in RAM. Only for large panoramas the OS will not
                  have
                  > enough cache memory and that's when the temporary files actually
                  start
                  > being written to disk.
                  >

                  I guess I'm missing something easy and fundamental. For fisheye
                  sperhical projects using only a GB or so, does this mean that using a
                  virtual RAM disk will have no benefit on any computer, not just my
                  slow, bloated one? Also, if everything is happening in RAM already
                  with a small stitch, why is there a hard disk bottleneck at all?



                  > This also means that PTGui should use all available RAM as long as
                  the
                  > OS is not doing anything else.
                  >
                  > These 'stitching speed' questions are always difficult to answer
                  since
                  > there are so many factors that influence the speed.

                  I bet. But I guess my interest in understanding the existing messy
                  hardware issues is so that I can purchase something that is optimized
                  for stitching, with a minimum of unknowns involved.

                  What I'm trying to decide at the moment is whether it's worth
                  investing in something like the iRAM disks, or whether virtual RAM
                  disks would do the same thing but better. These iRAM disks seem to
                  be an order of magnitude faster or more than the fastest spinning
                  disks. Any insights would be appreciated.

                  Thanks,
                  Matt
                • Joost Nieuwenhuijse
                  ... If you have enough RAM, yes. Windows will effectively emulate a RAM disk by means of file caching. ... For small panoramas there should not be a hard disk
                  Message 8 of 19 , Dec 4, 2007
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                    matt_nolan_uaf wrote:
                    > This is because PTGui was already using RAM..
                    >> PTGui stores temporary data in temp files, but due to the OS's file
                    >> system caching, the files never really get written to disk but
                    > instead
                    >> they are cached in RAM. Only for large panoramas the OS will not
                    > have
                    >> enough cache memory and that's when the temporary files actually
                    > start
                    >> being written to disk.
                    >>
                    >
                    > I guess I'm missing something easy and fundamental. For fisheye
                    > sperhical projects using only a GB or so, does this mean that using a
                    > virtual RAM disk will have no benefit on any computer, not just my
                    > slow, bloated one?

                    If you have enough RAM, yes. Windows will effectively emulate a RAM disk
                    by means of file caching.

                    > Also, if everything is happening in RAM already
                    > with a small stitch, why is there a hard disk bottleneck at all?

                    For small panoramas there should not be a hard disk bottleneck, assuming
                    that disk caching is enabled for your temp drive (thanks to Bernhard for
                    pointing that out..)

                    > What I'm trying to decide at the moment is whether it's worth
                    > investing in something like the iRAM disks, or whether virtual RAM
                    > disks would do the same thing but better. These iRAM disks seem to
                    > be an order of magnitude faster or more than the fastest spinning
                    > disks. Any insights would be appreciated.

                    I think it will not make much difference, but the only way to find out
                    is by trying. But that could be an expensive experiment, I agree..

                    Joost
                  • Bernhard Vogl
                    ... Well it s not as simple ;-) - quarter stroking *can* speed up head positioning as long as you don t use the other portions of the disk. But similar
                    Message 9 of 19 , Dec 5, 2007
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                      > Another trick I've read about is called quarter stroking your disk.
                      > Apparently you can create a partition on a 7500 RPM disk such that
                      > the partition is only using the inner portion of the disk, so that
                      > the arm doesnt move so far. Doing this is apparently faster than
                      > using a 15k SAS disk, and much cheaper, and plus you still get the
                      > slow part of the disk to use for storage.

                      Well it's not as simple ;-) - "quarter stroking" *can* speed up head positioning as long as you don't use the other portions of the disk. But similar concepts are implemented in nearly every file system driver. E.g. the middle of the disk is used to store directory information and the data is arranged around it. Chunks of a file are stored near to each other as long as there's enough space left for an optimal placement. Only if the filesystem is nearly full, the chunks are placed non-optimal.
                      This is the reason why you never should fill a files system above approx 70%.
                      Another thing to point out: It's not the inner side of the disk which is the fastest, it's the outer side. The disk surface below the head has an higher speed here, so you can store more data in a given time than on the inner side.

                      Just in case i didn't already mention: I strongly suggest everyone who is not perfectly sure what he's doing to use a standard setup instead of tweaking the system. There are chances that the system become worse than before...

                      Best regards
                      Bernhard
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