How fast is fast ??

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How fast is fast ??

Postby simonfbarnes on Tue Dec 28, 2010 8:11 pm

When I use FPV to browse my current folder of photos from xmas eve, which contains 900 70MB TIFFs, the screen is blank apart from a logo for about 25 seconds before the first photo is shown, and it's over a minute before the correct count of files in the folder is shown bottom right. This is on a 3GHz 4 core i7 CPU with a 2TB drive capable of 70MB/sec reads. I don't call this fast.
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Re: How fast is fast ??

Postby Axel on Thu Dec 30, 2010 6:30 pm

These are the clear signs of resource abuse 8-)

Pretty likely, the program is trying to load too many files at once, and the disk subsystem cannot deliver: it's called trashing where the disk heads are probably all over the place trying to grab all this data at once, attempting to serve all those cores, resulting in catastrophic performances.

The immediate workaround is to reduce preloading in the options (move the slider to the far left) or disable it altogether by unchecking the option, as well as disable parallel loading. With both options disabled, the program will load images one at a time, as fast as the disk can deliver them, and no trashing should occur. Defragmenting, if needed, can also smooth things out considerably.

You can then work from there and re-enable preloading, increasing it in small, conservative steps until you find the sweet spot that matches your heavy files and your disk's abilities.

As a side note, a fast disk subsystem starts at 300MB/s, as in SAS RAID, and would allow reading a mere 4 files per second given their size. Extra-large IDE/SATA disks are great for archival storage and offer excellent cost/capacity ratio, but are not exactly top performers when it comes to multi-tasking, multi-threaded I/O.

For users wanting to measure the average throughput of their drives, there is the free HD Tune 2.55 utility from http://www.hdtune.com (scroll down on their download page).
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Re: How fast is fast ??

Postby simonfbarnes on Thu Dec 30, 2010 11:51 pm

Yes, I think I'll have to buy an SSD to edit from! I'll try your suggestions and see what happens, however, surely multithreaded preloading is exactly what I want ? One thread to update the UI ASAP, another to background preload images ready for when I need them? For apparent speed, anything that takes more than 500mS needs to be removed from the foreground task, I don't mind waiting for the thumbnails to appear till much later...
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Re: How fast is fast ??

Postby Axel on Fri Dec 31, 2010 9:16 pm

Keep in mind that TIFF creates the largest files so the fastest disks will help greatly, and compressed TIFF is not very quick to unpack (compared to JPEG), try Photoshop and you'll see that at equal pixel dimensions, a JPEG gets loaded quicker than a TIFF.

Most users browse RAW files with FPV, and in most cases the embedded JPEG preview allows for a much quicker browsing experience: unpacking a 5MB JPEG is considerably quicker than a 70MB TIFF if the same pixel dimensions. On top of that, depending on your version of Windows, the TIFF codec may not be the best performer (Windows 7's version is great, or Vista's, provided you installed the Platform update). On Windows XP (or non-updated Vista), decoding large TIFF files is not very quick.

FastPictureViewer will use multiple CPU cores to preload/display in parallel, just make sure it does not overdo it by limiting the preloading, considering the very large size of your files 8-)
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