On 2014-12-30 21:36:19 +0530, Abhijit Menon-Sen wrote:
> Thanks for spotting that. I had meant to change the test to "& 7". But
> again, now that you mention it, I'm not sure it's necessary. The CRC32*
> instructions don't have the usual SSE alignment requirements, and I see
> that the Linux kernel (among other implementations) process eight bytes
> at a time from the start of the buffer and then process the remaining
> bytes one at a time. I'll do a bit more research and post an update.
I'd done some quick and dirty benchmarking when writing my initial
crc32c POC and I found that four byte aligned accesses were faster than
ones not. But it really just was running it a couple times, nothing more.
Greetings,
Andres Freund
-- Andres Freund http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
Services
