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Re: large file support in diff utils
From: |
Paul Eggert |
Subject: |
Re: large file support in diff utils |
Date: |
Mon, 11 Apr 2005 23:19:41 -0700 |
User-agent: |
Gnus/5.1006 (Gnus v5.10.6) Emacs/21.4 (gnu/linux) |
Chuck Swiger <address@hidden> writes:
> I mention this because I'd be curious to know what the memory and
> running time (big-O) of diff is.
That's discussed in the references, at least in theory.
> My experience suggests that you can't run diff against anything
> larger than a few 10's of MB before the program's memory usage
> exceeds MAXDSIZE on a 32-bit platform.
It depends on the data. Here's an example where it runs reasonably
fast on a 32-bit host (2.4 GHz P4). Admittedly not every case is this
fast....
$ ls -l /tmp/tar /tmp/tar1
-rw-r--r-- 1 eggert eggert 46325760 Apr 11 23:16 /tmp/tar
-rw-r--r-- 1 eggert eggert 46325764 Apr 11 23:16 /tmp/tar1
$ time diff -au /tmp/tar /tmp/tar1
--- /tmp/tar 2005-04-11 23:16:10 -0700
+++ /tmp/tar1 2005-04-11 23:16:24 -0700
@@ -1294184,4 +1294184,4 @@
" to corresponding destination files\n"
" -s, --strip strip symbol tables\n"
" -S, --suffix=SUFFIX override the usual backup suffix\n"
-" -t, --target-directory=DIRECTORY copy all SOURCE arguments int
\ No newline at end of file
+" -t, --target-directory=DIRECTORY copy all SOURCE arguments intabc
real 0m0.649s
user 0m0.140s
sys 0m0.470s