On 05/29/2013 05:19 PM, Jörn Engel wrote:
On Wed, 29 May 2013 22:37:00 +0200, Andi Kleen wrote:
As Dave said before, is the last path component sufficient? Or how
about an inode number?
Neither works, the profiler needs to find the file and read it.
Ignoring all the complexity this would cause downstream, you could do
the path lookup just once, attach some cookie to it and return the
cookie ever-after. Maybe some combination of i_sb and i_ino would be
good enough as a cookie.
Still, it is just shifting the complexity from the d_path code to the
perf kernel subsystem as it needs to keep track of what paths have been
sent up before. It also have complications in case the tracked files are
being deleted or moved around in the filesystem. Some kind of
notification mechanism has to be implemented in the dentry layer to
notify the perf subsystem.
Regards,
Longman
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