We are running the tests with the following mother board.
Its a very nice box with 2 independent 64/66 PCI buses.
Capable of 2x503MB/sec, using your logic ;)
Regardless, the 640MB/s number was computed without considering the PCI bus
limitations, or the dual port nature of the base 160MB/sec nature of the
Realistically, we are looking for a max throughput of about 320MB/sec with 4
adapters with enough drives attached.
2111 N.E. 25th Ave.
Hillsboro, OR 97124
> -----Original Message-----
> From: Christopher E. Brown [mailto:firstname.lastname@example.org]
> Sent: Saturday, June 22, 2002 9:03 PM
> To: Griffiths, Richard A
> Cc: 'Andrew Morton'; email@example.com; 'Jens Axboe'; Linux
> Kernel Mailing List; firstname.lastname@example.org
> Subject: [Lse-tech] RE: ext3 performance bottleneck as the number of
> spindles gets large
> 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...
> This of course assumes nothing else is using the PCI bus.
> 120 something MB/sec sounds a hell of a lot like topping out a 32bit
> 33Mhz PCI bus, but IIRC the earlier posting listed 39160 cards, PCI
> 64bit w/ backward compat to 32bit.
> You do have *ALL* of these cards plugged into a full PCI 64bit/66Mhz
> slot right? Not plugging them into a 32bit/33Mhz slot?
> 32bit/33Mhz (32 * 33,000,000) / (1024 * 1024 * 8) = 125.89 MByte/sec
> 64bit/33Mhz (64 * 33,000,000) / (1024 * 1024 * 8) = 251.77 MByte/sec
> 64bit/66Mhz (64 * 66,000,000) / (1024 * 1024 * 8) = 503.54 MByte/sec
> NOTE: PCI transfer rates are often listed as
> 32bit/33Mhz, 132 MByte/sec
> 64bit/33Mhz, 264 MByte/sec
> 64bit/66Mhz, 528 MByte/sec
> This is somewhat true, but only if we start with Mbit rates as used in
> transmission rates (1,000,000 bits/sec) and work from there, instead
> of 2^20 (1,048,576). I will not argue about PCI 32bit/33Mhz being
> 1056Mbit, if talking about line rate, but when we are talking about
> storage media and transfers to/from as measured by files remember to
> I route, therefore you are.
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