Sebastian wrote: > yea. all the files aren't 100MB though.. some are 2mb (even less) while > some > files are over 300MB as well. > so, does this need to be adjusted depending on the filesize? I believe that at a certain point, your setting there will be worse for the system if you make it too big instead of too small, regardless of the filesize to be written/read. This is because no matter how big your file is, there are buffers all along the chain of events between http://php.net/fread and the actual electrical signals re-aligning the magnetic spots on your hard drive disc. You're defining a buffer for fread. PHP may have an internal buffer in a layer deeper than that (probably not, but *could* have one) The C library may have a buffer in the next layer down. Again, probably not, but it *could* have one. The library inside the OS that the C library is calling maybe has a buffer. The OS File System that the OS library calls probably has a buffer. The physical hardware almost for sure has a buffer, probably several. If you have fancy hardware and/or RAID software, then there are even more buffers involved. And, of course, the RAM available to PHP at the time of doing this work will drastically affect performance -- If your server is loaded, and this fread with your (possibly over-sized) buffer forces PHP and/or the OS to swap something in/out to the hard drive, then you are going to KILL your system. At every step of the way, the data being buffered in a faster/cheaper storage medium will have an effect on your performance. Hopefully, for most uses, that is an overall Good effect. But nobody on Earth can tell you for sure for sure that it's all optimum for *YOUR* application's needs on *YOUR* hardware. So given your OS, and your hard drive and your file system, and your files, and the usual load on your server (RAM) there is some "ideal" number for that collection of hardware/software that you use. The only way to find your ideal number is to trial and error benchmark it. I'd try numbers that match up with: the cache size on the hard drive any internal buffers in PHP's fread() functions any buffer in your File System and/or OS of choice very large numbers very small numbers a random assortment of "nice" numbers (1Mb 2Mb 4Mb ...) Now, if your code has to run on LOTS of different hardware, you'd want to benchmark on as many different sets of hardware as you can to find the ideal number for *most* hardware. Or, you could, I suppose, try to write a system that detects certain specific categories of hardware/software and choose your buffer size based on that. Now, having said all that, the difference to the performance for MOST applications is going to be negligible. Find a number that works "fast enough" for your application (with reasonable testing/benchmarking) and move on with life. -- Like Music? http://l-i-e.com/artists.htm -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
