Hi, I cannot resist... in the following read my comments on caching and buffering.
Even Windows XP (did not try nore recent versions yet) suffers from bad buffering when copying files from and to the same harddrive. It takes 10x to 100x time compared to copying from one drive to another one. I installed SuperCopier 2.2 beta which catches Explorer copy actions and does them itself. Well, now you are able to define huge buffers... but it does not help much, because its a question of filling and flushing the buffer, as XCOPY did. !!! beware, supercopy has got a bug when using buffers larger than 64k, causing it to abort the operation on files larger than 4 gig. !!! Caching does not help much with operations like this. Ok, caching FAT and directories... When working with large files, you always have to code buffering on your own. For example, I compiled mplex (mpeg muxer) myself using cygwin. Works correctly but uses the wrong file mode. Result is my RAM gets filled with cached data from the target file. Everything else gets paged out. The system breaks down to almost unusable until the process is finished. Then it takes decades to swap in the other programs again... What I want to say is, you can have Terabytes of RAM, it won't help in a case like this when the file operation is about as large as your RAM. If there was an upper limit for the amount of cache used for a single file, there would be no problem at all. So small caches sometimes perform even better! So guys go tell M$ how to write an operating system! JPT ------------------------------------------------------------------------------ EMC VNX: the world's simplest storage, starting under $10K The only unified storage solution that offers unified management Up to 160% more powerful than alternatives and 25% more efficient. Guaranteed. http://p.sf.net/sfu/emc-vnx-dev2dev _______________________________________________ Freedos-user mailing list Freedos-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freedos-user
