Date: Wed, 14 Apr 2004 21:04:50 +0100 From: Colin Percival <colin.percival@wadham.ox.ac.uk> To: Dan Nelson <dnelson@allantgroup.com> Cc: Peter Jeremy <PeterJeremy@optushome.com.au> Subject: Re: Optimizing RCng execution speed ? Message-ID: <6.0.1.1.1.20040414210106.03b83830@imap.sfu.ca> In-Reply-To: <20040414194447.GD28745@dan.emsphone.com> References: <11095.1081621779@critter.freebsd.dk> <407B1EBC.6050405@freebsd.org> <407B234D.7070209@kientzle.com> <20040413160331.GM6308@numachi.com> <20040413200013.GC53327@cirb503493.alcatel.com.au> <6.0.1.1.1.20040414065121.039cde20@imap.sfu.ca> <407D78AB.1000700@kientzle.com> <20040414194447.GD28745@dan.emsphone.com>
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At 20:44 14/04/2004, Dan Nelson wrote: >In the last episode (Apr 14), Tim Kientzle said: >> 2) What is syslogd doing for 0.89 seconds? > >It is logging the kernel bootup output one line at a time, fsyncing >between lines. This can take a LONG time if you were just in >single-user mode and stored a lot of short shell lines in the kernel >buffer. I just remove the SYNC_FILE flag from line 741. Why is kernel >(and only kernel) log output fsynced anyway? I would assume that kernel log output is fsynced because the times when fsyncing is important are exactly the times when you're likely to want to see any errors logged by the kernel. That said, it seems that a useful optimization here would be to remove the SYNC_FILE until we kill our parent; syncing after each line doesn't help when we've got lots of lines waiting to be logged. Colin Percival
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