Unless I am mistaken if a high volume server is running one/two gigabit ethernet cards the NIC's are going to be using a ton of memery bandwidth themselves. Data doesn't just jump magically from HD to ethernet, it goes through RAM does it not. The CPUs in this server will never have access to more than half the available memory bandwidth meaning data can be moving on/off the HDs through a very fast NIC. Not all server applications are purely processor/memory speed limited. The ATA controllers will have DMA and so do NICs. All four ATA controllers, 2 NICs and 2 processors have to share the 2.1 GB/s. The overall speed would only sometimes benefit if they were on a 266 MHz bus.
. 133MHz system bus supporting over 1GB/s data throughput
Memory
. 256MB or 512MB of 266MHz PC2100 DDR SDRAM, with up to 2.1GB/s throughput
Just for clarification, I guess what people are saying is that even though the cpu communicates w/ the L-3 cache using DDR with up to 2.1 GB/s throughput, this really won't be much improvement, because the system bus only supports over 1GB/s data throughput when communicating with peripherals like the hard drives, PCI, etc. ???
<strong>Just for clarification, I guess what people are saying is that even though the cpu communicates w/ the L-3 cache using DDR with up to 2.1 GB/s throughput, this really won't be much improvement, because the system bus only supports over 1GB/s data throughput when communicating with peripherals like the hard drives, PCI, etc. ???
</strong><hr></blockquote>
The G4 communicates with its 2MB L3 cache at a max. data rate of 4GBps. It talks to the northbridge (or equivalent) at 1GBps (133MHz SDR), and the latter talks to the memory modules at 2.1GBps (133MHz DDR), and to the rest of the system via a 64bit / 66MHz PCI bus at 533MBps, plus additional dedicated ports for firewire, AGP and one GBit NIC.
As mentioned above, Apple's decision to use DDR in a machine with processors that can't leverage it is due to the large number of fast I/O devices this machine has. Since it is a server, I/O is particularly important and this setup ensures that the I/O subsystem gets as much memory bandwidth as the processors. For a rackmount server this makes a great deal of sense.
Given that they are limited by the 7455's memory bandwidth capabilities, this looks like a damn fine machine.
Only server benchmarks will show how fast these machines really are -- conventional benchmarks probably won't show much improvement over the PowerMacs.
Anybody else notice that these machines use ATI graphics chips? I guess ATI and Apple are friends again. The 8500 is quite comparable to the geForce4 Ti, by the way -- it is a bit slower in some ways, but has some capabilities that the nVidia chipset doesn't have.
<strong>Doesn't 266 DDR RAM run at 133Mhz with two transfers per clock cycle?
Just hearing there is still a 133Mhz bus doesn't seem to rule out the possibility that the processor is using the full DDR bandwidth.</strong><hr></blockquote>
They also state that the FSB supports "up to 1GBps", which rules out 133MHz DDR.
To be replaced by whom, exactly?</strong><hr></blockquote>
IBM. They've got the technology, they've got the fabs, they're not a cell phone company. Power4, the new 'Cell' chip, the continuing progress on the 750 series chips.....somewher in the confluence of all those things, they could put out a multi-purpose server/desktop/portable chip, if a good business oppurtunity came along.
IBM. They've got the technology, they've got the fabs, they're not a cell phone company. Power4, the new 'Cell' chip, the continuing progress on the 750 series chips...
</strong><hr></blockquote>
The Power4, nice as it may be, is a completely different market. For the cost of one Power4 processor module you could probably buy an XServe farm...
Also, where exactly is that mythical oh-so-fast G3 that IBM is supposed to have according to those ever-so-popular rumours that have been around for years now? As it stands, at this point, the fastest PowerPC processors currently available, both MHz-wise and generally, are manufactured by Motorola, not IBM.
<strong>IBM. They've got the technology, they've got the fabs, they're not a cell phone company. Power4, the new 'Cell' chip, the continuing progress on the 750 series chips.....somewher in the confluence of all those things, they could put out a multi-purpose server/desktop/portable chip, if a good business oppurtunity came along.</strong><hr></blockquote>
IBM huh?
Well, given all of the above, don't you think that perhaps they'd already have made moves if a) it was technically possible and b) financially worthwhile?
Even though the CPUs will only have a 1GBps pipe to the northbridge (and RAM through it) other IO that communicates with the nb like the PCI devices, ethernet, firewire, will and can make use of the extra bandwidth provided to by the DDR SDRAM.
Well, given all of the above, don't you think that perhaps they'd already have made moves if a) it was technically possible and b) financially worthwhile?</strong><hr></blockquote>
That's my point. If Apple were to make it financially worthwhile (i.e., promising to buy them), than IBM would probably be able to make it technically feasible.
<strong>That's my point. If Apple were to make it financially worthwhile (i.e., promising to buy them), than IBM would probably be able to make it technically feasible.</strong><hr></blockquote>
Given the costs of development, and assuming that there are some technical barriers with the current PowerPC design to be dealt with, perhaps no matter what Apple offers financially it just isn't enough?
<strong>Motorola's AltiVec license has Apple by the balls. I'm sure Apple would like to use better chips, but they need AltiVec.</strong><hr></blockquote>
The point is, even without AltiVec, you can't buy faster G3s from IBM either.
The point is, even without AltiVec, you can't buy faster G3s from IBM either.
Bye,
RazzFazz</strong><hr></blockquote>
yes this idiotic statement that IBM has better PPC chips has been there for too many times in this forums. Best G3 available until now : 700 mhz. Still waiting for the 750 fx. Fantastic chips in the roadmap : nothing shipping at the moment;
Comments
Just hearing there is still a 133Mhz bus doesn't seem to rule out the possibility that the processor is using the full DDR bandwidth.
. 133MHz system bus supporting over 1GB/s data throughput
Memory
. 256MB or 512MB of 266MHz PC2100 DDR SDRAM, with up to 2.1GB/s throughput
Just for clarification, I guess what people are saying is that even though the cpu communicates w/ the L-3 cache using DDR with up to 2.1 GB/s throughput, this really won't be much improvement, because the system bus only supports over 1GB/s data throughput when communicating with peripherals like the hard drives, PCI, etc. ???
<img src="confused.gif" border="0">
Apple's memory systems have been very efficient in the past, and I could imagine that this one is too.
In June we'll know, after someone has shoot through the usual benchmarks, STREAM etc...
G-news
<strong>Just for clarification, I guess what people are saying is that even though the cpu communicates w/ the L-3 cache using DDR with up to 2.1 GB/s throughput, this really won't be much improvement, because the system bus only supports over 1GB/s data throughput when communicating with peripherals like the hard drives, PCI, etc. ???
</strong><hr></blockquote>
The G4 communicates with its 2MB L3 cache at a max. data rate of 4GBps. It talks to the northbridge (or equivalent) at 1GBps (133MHz SDR), and the latter talks to the memory modules at 2.1GBps (133MHz DDR), and to the rest of the system via a 64bit / 66MHz PCI bus at 533MBps, plus additional dedicated ports for firewire, AGP and one GBit NIC.
Bye,
RazzFazz
[ 05-14-2002: Message edited by: RazzFazz ]</p>
Given that they are limited by the 7455's memory bandwidth capabilities, this looks like a damn fine machine.
Only server benchmarks will show how fast these machines really are -- conventional benchmarks probably won't show much improvement over the PowerMacs.
Anybody else notice that these machines use ATI graphics chips? I guess ATI and Apple are friends again. The 8500 is quite comparable to the geForce4 Ti, by the way -- it is a bit slower in some ways, but has some capabilities that the nVidia chipset doesn't have.
[ 05-14-2002: Message edited by: Programmer ]</p>
<strong>Doesn't 266 DDR RAM run at 133Mhz with two transfers per clock cycle?
Just hearing there is still a 133Mhz bus doesn't seem to rule out the possibility that the processor is using the full DDR bandwidth.</strong><hr></blockquote>
They also state that the FSB supports "up to 1GBps", which rules out 133MHz DDR.
Bye,
RazzFazz
<strong>
They also state that the FSB supports "up to 1GBps", which rules out 133MHz DDR.
Bye,
RazzFazz</strong><hr></blockquote>
Thanks.
TING5
<strong>Motorola should be fired.</strong><hr></blockquote>
To be replaced by whom, exactly?
Thanks, I was confusing communication between L 3 cache and the main memory. One day I may get it right.
<strong>
To be replaced by whom, exactly?</strong><hr></blockquote>
IBM. They've got the technology, they've got the fabs, they're not a cell phone company. Power4, the new 'Cell' chip, the continuing progress on the 750 series chips.....somewher in the confluence of all those things, they could put out a multi-purpose server/desktop/portable chip, if a good business oppurtunity came along.
Jet or TING5 or whoever I am
<strong>
IBM. They've got the technology, they've got the fabs, they're not a cell phone company. Power4, the new 'Cell' chip, the continuing progress on the 750 series chips...
</strong><hr></blockquote>
The Power4, nice as it may be, is a completely different market. For the cost of one Power4 processor module you could probably buy an XServe farm...
Also, where exactly is that mythical oh-so-fast G3 that IBM is supposed to have according to those ever-so-popular rumours that have been around for years now? As it stands, at this point, the fastest PowerPC processors currently available, both MHz-wise and generally, are manufactured by Motorola, not IBM.
Bye,
RazzFazz
<strong>IBM. They've got the technology, they've got the fabs, they're not a cell phone company. Power4, the new 'Cell' chip, the continuing progress on the 750 series chips.....somewher in the confluence of all those things, they could put out a multi-purpose server/desktop/portable chip, if a good business oppurtunity came along.</strong><hr></blockquote>
IBM huh?
Well, given all of the above, don't you think that perhaps they'd already have made moves if a) it was technically possible and b) financially worthwhile?
<strong>
IBM huh?
Well, given all of the above, don't you think that perhaps they'd already have made moves if a) it was technically possible and b) financially worthwhile?</strong><hr></blockquote>
That's my point. If Apple were to make it financially worthwhile (i.e., promising to buy them), than IBM would probably be able to make it technically feasible.
ting5
<strong>That's my point. If Apple were to make it financially worthwhile (i.e., promising to buy them), than IBM would probably be able to make it technically feasible.</strong><hr></blockquote>
Given the costs of development, and assuming that there are some technical barriers with the current PowerPC design to be dealt with, perhaps no matter what Apple offers financially it just isn't enough?
<strong>Motorola's AltiVec license has Apple by the balls. I'm sure Apple would like to use better chips, but they need AltiVec.</strong><hr></blockquote>
The point is, even without AltiVec, you can't buy faster G3s from IBM either.
Bye,
RazzFazz
<strong>
The point is, even without AltiVec, you can't buy faster G3s from IBM either.
Bye,
RazzFazz</strong><hr></blockquote>
yes this idiotic statement that IBM has better PPC chips has been there for too many times in this forums. Best G3 available until now : 700 mhz. Still waiting for the 750 fx. Fantastic chips in the roadmap : nothing shipping at the moment;