On Sun, Jan 20, 2008 at 10:20:46AM -0800, Linus Torvalds wrote: > But I guess that was a bit optimistic. On Linux, we still had about 50% > user time, and I guess the same is _largely_ true on Windows. Cutting the > system time in half only gives you about a quarter performance > improvement, and I was just incorrect in expecting system calls to be the > limiting factor. > > [...] > > fnmatch? It's certainly visible on Linux, I wonder if the Windows/OSX > version is more expensive due to trying to be case-insensitive or > something?
Windows (msys) Git, with the lstat patch and on my 15433-file test case, is at least 90-95% system time. I don't have any good tools for measuring this, but just using the silly performance monitor you get with ctrl-alt-del and enabling the "View -> Show Kernel Times" curve on the graph shows this fact pretty clearly. I think this shows that: 1. There's not much overhead in msysGit's stat wrapper at all. It gets converted quite efficiently to native Windows calls. 2. Windows really sucks at filesystem ops. Film at 11. One thing I dimly recall is that the nightmare interface of FindFirstFile/FindNextFile (which I assume is what is actually getting called for opendir/readdir) actually returns some stat information with each file. Would it be possible to use that directly in some cases rather than taking an extra stat call to get it? -bcd
