On 12/12/2013 11:27, Pieter De Wit wrote:
Hi List,
Given the recent work done with techs like CUDA etc. - has the idea
been floated to use the video card for RAID parity calculations vs the
CPU ?
Sending the XOR computation to the GPU is like shooting a fly with a cannon.
The bandwidth to the GPU would be the bottleneck by 2 orders of
magnitude if you try to do this.
XOR is a way too simple operation. Even if it was a stream of double *
double multiplications, the bottleneck would lie in the bandwidth
to/from the GPU.
You can gain something only if you do a matrix multiplication where each
float or double is uploaded only once but reused many times in all the
row x column multiplications.
The best performers on the GPU are the autoctonous applications, which
operate autonomously and communicate very little with the CPU for a very
long time.
The XOR computation is WAY fast enough on modern processors. There is a
benchmark at boot about this:
dmesg | grep "raid6: using algorithm"
returns:
[ 5.072162] raid6: using algorithm sse2x4 (7556 MB/s)
7.5 GB/sec, and that's raid6, not even XOR.
Probably even single-threaded.
(probably this does not include the memory-copy overhead)
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
