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Re: [Gnu-arch-users] Slow inventories on large source trees

From: Aaron Bentley
Subject: Re: [Gnu-arch-users] Slow inventories on large source trees
Date: Thu, 22 Apr 2004 12:14:53 -0400
User-agent: Mozilla Thunderbird 0.5 (X11/20040309)

Tom Lord wrote:
I assume that you are passing a regmatch_t array with just one
element, right?


The cut operator can work with just a simple DFA translation of a
regexp -- and Rx supports that internally -- but it appears that the test for whether or not that optimization applies within the posix
entry points doesn't know about `cut'.   It's as if you had asked for
a full set of `regmatch_t' values --- Rx is doing lots of backtracking
work on every match.

Note also that the it's filename_matches (which is untouched) that's consuming most of the runtime, not filename_matches_cut (which is a variant of the above that returns the cut matched).

I suppose it's possible that the demands of filename_matches_cut leave a cache in disarray, causing filename_matches to work much harder.


Aaron Bentley
Director of Technology
Panometrics, Inc.

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