Re: SpeedComparison
От | Kenneth Marshall |
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Тема | Re: SpeedComparison |
Дата | |
Msg-id | 20060211225048.GA447@it.is.rice.edu обсуждение исходный текст |
Ответ на | Re: SpeedComparison (Jochem van Dieten <jochemd@gmail.com>) |
Ответы |
Re: SpeedComparison
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Список | pgsql-hackers |
On Sat, Feb 11, 2006 at 09:21:43PM +0100, Jochem van Dieten wrote: > On 2/11/06, Andrej Ricnik-Bay wrote: > > Has anyone here seen this one before? Do the values > > appear realistic? > > > > http://www.sqlite.org/cvstrac/wiki?p=SpeedComparison > > The values appear to originate from an intrsinsically flawed test setup. > > Just take the first test. The database has to do 1000 commits. That > means 1000 I/O operations. There is no way that a 7200 RPM disk can do > that in the time that that test says it took. It is reasonable to say > that a disk can do 1 I/O operation per rotation, which means that any > test result below 9 seconds is untrustworthy. > > Jochem > Jochem, If the heads of the disk are in the right location, you could easily do more than 1 commit per disk revolution so the values over 2 seconds could actually be valid. 9 seconds would be worst case of 1 commit per revolution. Ken
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