On Apr 19, 2008, at 11:53 , Murray Gross wrote:
2. You need to account for I/O buffering (not only by your OP system in RAM, but by your disk controller)--after the first set of I/O operations, your data may be in buffers, so subsequent uses may retrieve data from buffers rather than from the disk itself. Similarly, you also have to take into account paging and cache issues, which could make the first run much slower than immediate subsequent runs.
Note also that, unless you use SCSI or very high-end SATA drives, they ignore requests to disable buffering. (References on request, you can probably find them by poking around http://www.pdl.cmu.edu/. Short summary: consumer drives are optimized for benchmarks, not for data safety. This is why early 32-bit Windows releases often lost data on shutdown until the shutdown was modified to sleep for 10-15 seconds.)
-- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] [EMAIL PROTECTED] system administrator [openafs,heimdal,too many hats] [EMAIL PROTECTED] electrical and computer engineering, carnegie mellon university KF8NH _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
