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Date: Sun, 23 Jun 2002 00:00:01 -0600 (MDT)
From: "Christopher E. Brown" <cbrown@woods.net>
To: Andreas Dilger <adilger@clusterfs.com>
Cc: "Griffiths, Richard A" <richard.a.griffiths@intel.com>,
       "'Andrew Morton'" <akpm@zip.com.au>, <mgross@unix-os.sc.intel.com>,
       "'Jens Axboe'" <axboe@suse.de>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
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Subject: Re: ext3 performance bottleneck as the number of spindles gets large
In-Reply-To: <20020623043310.GL22411@clusterfs.com>
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On Sat, 22 Jun 2002, Andreas Dilger wrote:

> On Jun 22, 2002  22:02 -0600, Christopher E. Brown wrote:
> > On Thu, 20 Jun 2002, Griffiths, Richard A wrote:
> >
> > > I should have mentioned the throughput we saw on 4 adapters 6 drives was
> > > 126KB/s.  The max theoretical bus bandwith is 640MB/s.
> >
> > This is *NOT* correct.  Assuming a 64bit 66Mhz PCI bus your MAX is
> > 503MB/sec minus PCI overhead...
>
> Assuming you only have a single PCI bus...


Yes, we could (for example) assume a DP264 board, it features 2/4/8
way memory interleave, dual 21264 CPUs, and 2 separate PCI 64bit 66Mhz
buses.

However, multiple busses are *rare* on x86.  There are alot of chained
busses via PCI to PCI bridge, but few systems with 2 or more PCI
busses of any type with parallel access to the CPU.


 --
I route, therefore you are.

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