Ping? On Mon, Apr 18, 2016 at 12:38 AM, NightStrike <nightstrike@xxxxxxxxx> wrote: > Also, FWIW: > > 1) The march=native version that uses prefetcht0 is very repeatedly > faster by about 15% in the particular test case I'm looking at. > > 2) The compilers in both instances are not just the same version, they > are the same compiler installed on an NFS mount and shared to both > computers. > > > On Mon, Apr 18, 2016 at 12:26 AM, NightStrike <nightstrike@xxxxxxxxx> wrote: >> Not sure if this applies: >> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54210 >> >> If I compile on a k8 Opteron 248 with -march=native, I do not see >> -mprfchw listed in the options in -fverbose-asm. In the assembly, I >> see this: >> >> prefetcht0 (%rax) # ivtmp.1160 >> prefetcht0 304(%rcx) # >> prefetcht0 (%rax) # ivtmp.1160 >> >> If I compile on a bdver2 Opteron 6386 SE with -march=k8 (thus trying >> to target the older system), I do see it listed in the options in >> -fverbose-asm. In the assembly, I see this: >> >> prefetcht0 (%rax) # ivtmp.1160 >> prefetcht0 304(%rcx) # >> prefetchw (%rax) # ivtmp.1160 >> >> (The third line is the only difference) >> >> In both cases, I'm using gcc 4.9.3. Which is correct for a k8 Opteron 248?
