"welch" <[EMAIL PROTECTED]> wrote: > while taking some rough disk performance measures on windows machines, > and snooping with FileMon, i've noticed some odd behavior
> sometimes, depending on the phase of the moon, instead of > $ReplaceAttribute2 the write goes to $ConvertToNonresident. within a > single run of writeTest the write always goes to the same one, > whichever one that is. these runs are always slower (sometimes greatly) > than writing the same with 64K blocks, even though many fewer > file.write()'s are being issued because of the larger block size. > > finally, where you'd expect an even 10 of the WRITE > C:\$ReplaceAttribute2 lines per WRITE C:\writeTest.out lines in the > example above, instead FileMon reports 8 lines for the first, 6 for the > second, 8 for the third, 6 for the fourth, etc... i've no idea if this > means FileMon is missing messages, but this pattern is absolutely > consistent across every run i've made, on both xp and win2k3 server > machines. > > a look at the python fileobject.c source shed no light for me, anyone > know what could be going on? the "equivalent" c version of writeTest > using fwrite() shows a succession of 1K blocks writing to the named > file (even when fwrite is given 64K blocks), and no mysterious > $ReplaceAttribute2 lines you're seeing activities by the Windows caching system (c:\$ stuff is various NTFS data streams). unless you're writing low-level drivers, you don't really have to care about what it does, and when it does what... </F> -- http://mail.python.org/mailman/listinfo/python-list
