On 12/11/2015 03:49, Li, Liang Z wrote:
> I am very surprised about the live migration performance result when
> I use your ' memeqzero4_paolo' instead of these SSE2 Intrinsics to
> check the zero pages.
What code were you using? Remember I suggested using only unsigned long
checks, like
unsigned long *p = ...
if (p[0] || p[1] || p[2] || p[3]
|| memcmp(p+4, p, size - 4 * sizeof(unsigned long)) != 0)
return BUFFER_NOT_ZERO;
else
return BUFFER_ZERO;
> The total live migration time increased about
> 8%! Not decreased. Although in the unit test your '
> memeqzero4_paolo' has better performance, any idea?
You only tested the case of zero pages. But real pages usually are not
zero, even if they have a few zero bytes at the beginning. It's very
important to optimize the initial check before the memcmp call.
Paolo
