CompuServe Thread

Hi Ian, There aren't any known bugs with swapping on the SGI renderer, although there are some differences from the PC version. On the PC when you swap to disk, the swap space is dynamicaly allocated, taking as much hard disk space as needed until there is literrally no more space available. On the SGI's the swap space is pre-allocated. Thus, if you have not preallocated enough swap space, the proccess could crash because it ran out of system resources or swap space, even if there are gigabytes of hard disk space available. It is very difficult to calculate how much memory will be needed ahead of time, because the SGI swap files are typically much bigger than those on the SGI, and the equations we have for elements in the scene and how many bits of rendering memory each needs allocated are different for the SGI than they are for the PC. (Right now, we only have the PC side.) So…trial and error is the only way to determine whether you have enough swap space allocated. If your rendering process crashes, there are two places to look. The first is the console window on the SGI. There might be system messages sent to that window. The second place ( and the best place for checking things out) is the network log that is generated when you start the network render process. (This assumes that you send the job from a PC, and are not using command line rendering. ) In the network log, you will see an entry for each frame that shows memory and swap space used, like this: [03:22:52] Machine 4368 [GRUMPY-BRIANR] assigned frame 300 [03:24:26] Machine 4368 [GRUMPY-BRIANR] completed frame 300 [03:24:26] [GRUMPY-BRIANR] Frame elapsed time: 0:01:34 (94 seconds) [03:24:26] [GRUMPY-BRIANR] Avail:67108864 Used:62152704 Swap:17276928 You will get this for every frame rendered. Using this information, you can see how the memory needs of your scene change over time, and this log will also tell you if a frame did not have enought memory to render and the process was halted. This is the best way to check to see if you are having swap file problems. Also, as you surmised, the sheer amount of bitmaps you have, and their size, may be causing a problem as well. One of the requirements of rendering when using a bitmap in the scene is that a portion of that bitmap must be stored in physical RAM, and can not be allocated to virtual memory. On the PC, the "No RAM for Bitmap" error will occur if there is not enough phisical RAM to load all the images simultaneously and hold that minimum amount of the images scanlines in the physical RAM. You might be experiencing the same thing. -Brian

You're running out of swap space. Run "swap -l" and check what you have available. Check "man swap" for more options, including the option of using "virtual" swap space (where the swap space grows as needed depending on disk space).

Colin, it looks like you've received some good advice from the crew. FWIW, we have 2.4 gb of swap space on our Challenger XL (1gb RAM, 8 cpu's) and it runs very nicely that way. We've thrown some huge projects at it, but I don't think we've caused it to page yet.