Re: [Gnu-arch-users] ANNOUNCEMENT -- "timestamps" optimization

[Tom Lord]

    > From: Jason McCarty <address@hidden>

    > I did a little speed testing on Linux 2.4 (ext3 fs), with patch-160 and
    > patch-162. Times reported are total time (including IO/system time).

To be clear: you mean that you tested on a 2.4 platform using the tla
tree as your test case, right?

    > User time was 2.7-2.8s on every run, so it looks like tree-traversal
    > costs trump file-comparing costs, regardless of how many files are
    > compared. 

For a tla-sized tree, that's not too surprising.  If you're testing
against a much larger tree, that'd be surprising.


    > So the real effect of the inode-signature optimization is to
    > reduce kernel cache usage, rather than reducing cpu time
    > significantly.

That's right.   And for large trees (that press up against or past the
cache size) that also means less disk i/o, which has been the apparent
bottleneck on kernel-sized trees.


Thanks for the results,
-t