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Re: problems with new vacuum (??)

From: Don Baccus <dhogaza(at)pacifier(dot)com>
To: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
Cc: "Matthew T(dot) O'Connor" <matthew(at)zeut(dot)net>, Barry Lind <barry(at)xythos(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: problems with new vacuum (??)
Date: 2002-01-02 18:34:35
Message-ID: 3C3352BB.5020008@pacifier.com (view raw or flat)
Thread:
Lists: pgsql-hackers
Bruce Momjian wrote:

>>In my experience enabling this feature can make a huge improvement in I/O 
>>intensive applications.  Other options can help also, but I find dma to have 
>>the largest impact.  I find linux almost unusable without it.
>>
> 
> Oh, I should mention my BSD/OS data point is with one SCSI disk, soft
> updates and tagged queuing enabled.


If Tom's system is IDE-based and he's not explicitly enabled DMA then 
this alone would explain the difference you two are seeing, just as the 
poster above is implying.  I have one system with an older 15GB disk 
that causes a kernel panic if I try to enable DMA, and I see the kind of 
system performance issues described by Tom on that system.

On my main server downtown (SCSI) and my normal desktop (two IDE drives 
that do work properly with DMA enabled) things run much, much better 
when there's a lot of disk I/O going on.  These are all Linux systems, 
not BSD...


-- 
Don Baccus
Portland, OR
http://donb.photo.net, http://birdnotes.net, http://openacs.org


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