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From: William Lee Irwin III <>
To: Per Andreas Buer <>
Subject: Re: 2.4: mylex and > 2GB RAM
Date: Mon, 8 Dec 2003 12:22:29 -0800	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

William Lee Irwin III <> writes:
>> If your memory ended at 2GB and the driver had 31-bit DMA, it may have
>> decided to use unconstrained allocations. Then, when you added more RAM,
>> it was forced to ask for <= 896MB, which made it copy to buffers that are
>> actually below 896MB most of the time.

On Mon, Dec 08, 2003 at 09:15:15PM +0100, Per Andreas Buer wrote:
> But this would reduce the throuput only a few percent, right? My system
> slows down from writing ~ 100MB/s to maybe 50KB/s. 

It could potentially slow it down a lot more than a few percent.

The main effect you would see is heavy low memory consumption (LowFree:
going down to almost nothing) and very heavy cpu consumption.

-- wli

  reply	other threads:[~2003-12-08 20:22 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-12-08 15:24 2.4: mylex and > 2GB RAM Per Buer
2003-12-08 15:36 ` William Lee Irwin III
2003-12-08 15:54   ` Per Buer
2003-12-08 16:22     ` William Lee Irwin III
2003-12-08 20:15       ` Per Andreas Buer
2003-12-08 20:22         ` William Lee Irwin III [this message]
2003-12-08 21:01           ` Per Andreas Buer
2003-12-08 21:02             ` William Lee Irwin III
2003-12-08 21:25               ` Per Andreas Buer
2003-12-08 21:36                 ` William Lee Irwin III
2003-12-09 10:31             ` Marcelo Tosatti
2003-12-10 13:21               ` Per Buer
2003-12-08 20:40         ` Zwane Mwaikambo
2003-12-08 15:58 Hank Leininger

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