Will Murnane wrote: > On 8/14/07, Andrew Suffield <[EMAIL PROTECTED]> wrote: >> That seems correctable. Pass the log through tac, use head instead of >> tail, and pass the output of head through tac again. > 'tail' is much faster. Even with a huge file (the one I tested with > is 26 gigabytes) it simply mmap()s the file and then scans backwards > until it's got enough newlines - it took about 1/20th of a second on > that 26GB file. Perhaps shorewall is using a different, less > efficient method?
The log file can have other record types besides netfilter messages. So Shorewall was piping the output of 'grep' through 'tail' which doesn't permit that optimization. As I reported in the earlier post, switching to Andrew's algorithm does improve performance. -Tom -- Tom Eastep \ Nothing is foolproof to a sufficiently talented fool Shoreline, \ http://shorewall.net Washington USA \ [EMAIL PROTECTED] PGP Public Key \ https://lists.shorewall.net/teastep.pgp.key
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