Hi Tom, >>> More tests: http://jafile.com/uploads/dos386/perftest.txt > unless dos386 describes what program(s) he used on what hardware > to produce these results, the data are useless :( > >> ...you can try first writing some dummy data at where the file >> will end, then close it and re-open (without truncate of course) >> and do the actual copy. That should bundle the FAT updates and >> increase performance significantly :-) > just did exactly this (for command.com) COPY. > unfortunately performance remains the same. > > for a single drive (that is able to read ~43 MB/sec), using > a copy buffer of 60K (Freecom default), copy performs > roughly identical, even if the file is pre-created.
Please explain. You compiled a modified version of the built-in COPY command of command.com? My suggestion was to pre-grow the file, not only pre-create it. Something like, ca 2 GB example: - open and create a new file for writing - seek to offset ca 2 GB (works even though file is still empty) - write 1 byte of data at this place - close the file (this should allocate all clusters for a full 2 GB file in FAT) - open file for writing (no truncate) - file is now 2 GB but data is "random" contents of whatever was in the before-unused clusters unless your kernel was compiled with WRITEZEROS (normally not the case) - write 2 GB of normal data to the file in big chunks, preferrably with a copy buffer not wrapping a linear 64 kB offset and with a size which is a multiple of 1 cluster. (should only have to write data, FAT unchanged, few seeks, in particular if FAT data can use BUFFERS or a read cache) Eric PS: http://jafile.com/uploads/dos386/perftest.txt says the test involves R/W of one file of 2'400'000'000 Bytes but it does not specify which int21 functions or tools were used. ------------------------------------------------------------------------------ All of the data generated in your IT infrastructure is seriously valuable. Why? It contains a definitive record of application performance, security threats, fraudulent activity, and more. Splunk takes this data and makes sense of it. IT sense. And common sense. http://p.sf.net/sfu/splunk-d2d-c2 _______________________________________________ Freedos-kernel mailing list Freedos-kernel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freedos-kernel
