Sony PS4 Effective GPU Bandwidth is 140 GB/s Not 176 GB/s - Disproportionate CPU and GPU Scaling
[Editorial] Something very interesting was given to me recently. A slide from a PS4 presentation which showed the total bandwidth of the PS4 GPU. The Bandwidth in question is claimed by most PR documents to exist around 176GB/s equally most of you lot know, simply it turns out that the bodily bandwidth is somewhere around 140GB/s and drops even more than when heavy CPU utilization occurs. While the latter isn't particularly shocking, the aforementioned can't be said for the actual bandwidth limit. Earlier I brainstorm, let me state that I have dropped Sony PR an email and will update this editorial equally soon equally I get a response.
PS4 GPU has an Effective Bandwidth of 120 to 140 GB/s, Not 176 GB/s As Previously Reported
The slide comes from a technical presentation of the Sony PS4 system and equally such, it must be treated with the utmost caution. Nevertheless, from what I tin run into, if at that place is one thing you cannot deny, its that the effective/usable/actual (whatever you want to call information technology) bandwidth available to the Pitcairn GPU of the PS4 is 120GB/s to 140GB/s. Past this I mean the actual bandwidth available to the developers to play with. The problem is, this is something that cant really happen. Non unless the memory clock we know is incorrect also. Confused? let me explain. The bandwidth and the effective retentiveness clock are linked. this is how the equation goes. Lets presume a memory clock 5500 Mhz and a bus of 256Bits. This is how the equation will go [5500 Mhz * 256 $.25 = 1408000] then [1408000/(8*1000) = 176]. As y'all can run across, a memory clock of 5.5Ghz and 256 bit bus has to result in 176 GB/s bandwidth. Unless, i of the other variables are incorrect, or the basic premise is flawed. 
So option 1 that we have is that the graph is incorrect or skewed due to an unknown factor, however considering there are actually iv samples present, I am don't think that'due south the case. The second option is that the retentiveness clock is wrong and the concluding option being the Bus being wrong. At present needless to say, the charabanc being wrong is quite improbable. Reversing the previously used equation nosotros get [(140x1000x8)/256 = 4375Mhz] and [(120x1000x8)/256 = 3750Mhz]. This is now start to brand some semblance of logic. The retention appears to be downwards clocking as the CPU usage increases and this is where the ''disproportionate'' role comes into play. Theoretically as the APU varies between CPU intensive and GPU intensive tasks the bandwidth should remain the aforementioned, 140 in this case. But it doesn't. The full bandwidth of the system actually drops to as much as 120 GB/s and more than if the trend continues. If yous take a expect at the graph you will detect that the CPU bandwidth is actually cipher in the bar where the GPU bandwidth is highest. Since this is a realistic impossibility, even with very low usage y'all are looking at well-nigh 135GB/due south of Bandwidth at max. This is a very interesting development and is probably the result of the fact that at the eye of the PS4 is an APU.
#Sony #PS4 actually has 140GB/s Bandwidth, not 176. < This, is very weird.http://t.co/DzbUaowTMq
— Usman Pirzada (@usmanpirzada) Baronial 20, 2022
Source: https://wccftech.com/sony-ps4-effective-bandwidth-140-gbs-disproportionate-cpu-gpu-scaling/
Posted by: dyerhusith.blogspot.com
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