memory bandwidth with ECC on

Hi, everyone,

We can easily get the hardware value of the GPU memory bandwidth with ECC off (e.g. 177 Gbytes/sec for Tesla M2090), but how about the memory bandwidth with ECC on? Is it also reduced by 12.5%?

Thank you in advance!

Why not simply measure it both ways? For example, on my K20c here I measure the following STREAM bandwidth (standard double-precision variant, i.e. 64-bit accesses):

ECC off 170.5 GB/sec +/-1%
ECC on 150.0 GB/sec +/-1%


I was actually asking for “the hardware value of the GPU memory bandwidth”. But anyway, based on your tests, it seems that the ECC may reduce it by 12.5%, which confirms my presumption.

My understanding is the impact of ECC on memory bandwidth depends on the access pattern, so it is not possible to state a single “hardware value”. For a given app, the impact of turning ECC on or off should be easy enough to determine.