Kamil Dudka wrote: > On Thu October 22 2009 16:42:48 Jim Meyering wrote: >> Have you measured the performance penalty it incurs? >> I hope it is possible to do the same thing, but with less of a penalty. >> >> I'm afraid we'll have to do something like that one way or >> another. At best, the impact will be so small that we won't >> even have to provide a new "flag" to enable it. ... > There is no measurable performance penalty, assuming you have more files than > directories in the tree (which is IMO the common use case). I am attaching > also a filtered strace output showing the cost of the second stat call: > > # strace -rve trace=openat,newfstatat -o trace.raw du -sh /var > # grep -A1 -B1 openat trace.raw | lzma -c > trace.lzma
Hi Kamil, Sorry about the delay. I'm trying to reconcile this file system's behavior with fundamental assumptions about unchanging device/inode, and as a result am having second thoughts. What event causes the directory's stat.st_dev to change? Opening the directory? Calling readdir? Accessing one of its entries? Can you describe how to reproduce the problem on rawhide or Fedora 12? Jim
