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Re: Tryint to match Solaris-Oracle performance with directio?

From: Gaetano Mendola <mendola(at)bigfoot(dot)com>
To: ischamay(dot)andbergsay(at)activestateway(dot)com
Subject: Re: Tryint to match Solaris-Oracle performance with directio?
Date: 2004-09-17 23:42:25
Message-ID: 414B7661.7000108@bigfoot.com (view raw or flat)
Thread:
Lists: pgsql-performance
Mischa Sandberg wrote:
> In the meantime, what I gather from browsing mail archives is that 
> postgresql on Solaris seems to get hung up on IO rather than CPU.
> Furthermore, I notice that Oracle and now MySQL use directio to bypass 
> the system cache, when doing heavy writes to the disk; and Postgresql 
> does not.
> 
> Not wishing to alter backend/store/file for this test, I figured I could 
> get a customer to mount the UFS volume for pg_xlog  with the option 
> "forcedirectio".
> 
> Any comment on this? No consideration of what the wal_sync_method is at 
> this point. Presumably it's defaulting to fdatasync on Solaris.
> 
> BTW this is Postgres 7.4.1, and our customers are Solaris 8 and 9.

If you care your data upgrade to more recent 7.4.5

Test your better sync method using /src/tools/fsync  however do some
experiment changing the sync method, you can also avoid to update the
acces time for the inodes mounting the partition with noatime option
( this however have more impact on performance for read activities )


Regards
Gaetano Mendola



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