Re: Report of performance on Alpha vs. Intel - Mailing list pgsql-general

Memory and cache are the most important parameters for db server, and PC
lacks both.

At 19:14 5.9.2000 , Steve Wolfe wrote:
>
>   This week, I had the opportunity to compare the performance of PostgreSQL
>on an Alpha and an Intel server, and the results kind of surprised me.  I'd
>love to hear if this has been the case for others as well...
>
>-------------
>Intel Machine
>
>SuperMicro 8050 quad Xeon server
>512 MB RAM
>4 x PII Xeon 400 MHz (secondary cache disabled)
>RAID array w/ 5 9-gig drives
>
>Approximate cost:  $6000
>--------------
>Alpha Machine
>AlphaServer DS20E
>2 x CPU (500 MHz or 667 MHz)
>2 GB RAM
>9-gig SCSI drive
>
>Approximate cost:  $20,000 - $25,000
>-----------------------
>
>General System notes
>
>    I'm not sure which chips the Alpha uses, the 500 MHz or the 667 MHz.
>Also, because the SuperMicro board is meant for the newer Xeons, the
>secondary cache had to be completely disabled on the PII 400 Xeons, so that
>machine was definitely not running up to potential.
>
>-------------------------
>Test method
>
>   This wasn't exactly the ANSI tests, but it accurately reflected what we
>need out of a machine.  A while back we logged 87,000 individual queries on
>our production machine, and I selected one thousand distinct queries from
>that.
>
>   On each machine I spawned 20 parallel processes, each performing the
>1,000 queries, and timed how long it took for all processes to finish.
>
>   To try and keep the disk subsystem from being a factor, this used only
>selects, no updates or deletes.  Also, the database is small enough that the
>entire thing was easily in the disk cache at all times.
>--------------------------
>Test results
>
>  The Alpha finished in just over 60 minutes, the Xeon finished in just over
>90.
>
>-----------------------------
>Test interpretation
>
>  Once I started looking at the numbers, I was suprised.  On a
>processor-for-processor basis, the Alpha was three times as fast as the
>Intels.  However, the Intels that it was pitted against were only 400 MHz
>chips, only PII (not the PIII), *and* had the external cache completely
>disabled.
>
>   So, the Alpha provided three times the performance for four times the
>cost - but if the megabyte of cache had been enabled on the Xeons, I think
>that the results would have been significantly different.  Also, if the
>chips had been even relatively recent chips (say, some 700 or 800 MHz Xeons)
>with the cache enabled, it's possible that it could have come close to the
>performance of the Alpha, at a much lower cost.
>
>  Overall, I was expecting the Alpha to give the Intel a better trouncing,
>especially considering the difference in cost, but I guess it's hard to beat
>Intel for transactions/dollar.  If sheer server capacity is the only
>relevant factor, forget Intel (You won't find Intels with 64 processors, and
>I don't think you'll see them even with the Itaniums).  If your needs are
>more down-to-Earth, they're the best you can get for the money.
>
>steve
>
>
v
Zeljko Trogrlic
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Aeris d.o.o.
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