On Tue, 27 Nov 2007, Scott Ribe wrote:
> IIRC, it was later established that during those tests they had fsync
> enabled on OS X and disabled on Linux.
You recall correctly but I'm guessing you didn't keep up with the
investigation there; I was tempted to bring this up in that last message
but was already running too long.
Presumably you're talking about http://ridiculousfish.com/blog/?p=17 . The
fsync theory was suggested by them and possibly others after Anandtech's
first benchmarking test of this type.
The second test that I linked to rebutted that at
http://www.anandtech.com/mac/showdoc.aspx?i=2520&p=6 . This specific
issue is also addressed by a comment from Johan Of Anandtech on the
ridiculousfish site. The short version is that the MySQL they were using
had a MyISAM configuration that doesn't do fsyncs, period, so it's
impossible fsyncs were to blame. You only get fsync if you're running
InnoDB. I think the reason for this confusion is that at the time of the
initial review, working MySQL fsync under OS X was pretty new (January
2005 I think, http://dev.mysql.com/doc/refman/4.1/en/news-4-1-9.html )
Ultimately, the exact cause here doesn't change how to clear the air here.
As I suggested, the only way to refute benchmarks showing awful
performance is not to theorize as to the cause, but to show new ones that
disprove the first ones are still accurate. If you can point me to one of
those, I'd love to see it--this is actually one of the items on the
relatively short list of why I'm typing this on a Thinkpad running Linux
instead of a Macbook (the other big one is Apple's string of Eclipse
issues, which I already ranted about recently at
http://slashdot.org/comments.pl?sid=342667&cid=21154137 )
--
* Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD
