On Friday 13 November 2015 10:05:28 Baolin Wang wrote: > > Well, I did a simple test with dd reading, cause my engine limitation is 1M, > (1) so the time like below when handle 1M at one time. > 1048576 bytes (1.0 MB) copied, 0.0841235 s, 12.5 MB/s > 1048576 bytes (1.0 MB) copied, 0.0836294 s, 12.5 MB/s > 1048576 bytes (1.0 MB) copied, 0.0836526 s, 12.5 MB/s > > (2) These handle 64K at one time * 16 times > 1048576 bytes (1.0 MB) copied, 0.0937223 s, 11.2 MB/s > 1048576 bytes (1.0 MB) copied, 0.097205 s, 10.8 MB/s > 1048576 bytes (1.0 MB) copied, 0.0935884 s, 11.2 MB/s > > Here is a 10ms level difference, try to image if the hardware engine's > throughput is bigger than that. But like Jens said, we can measure it > by the performance data. The absolute numbers look really low. Does this include writing to a hard drive? That would certainly make the difference appear less significant. Could you try backing this with a ram disk backing for comparison, and also use 'time dd' to show the CPU utilization for all cases? For completeness, including cpu-only performance might also help put this into perspective. Arnd -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
