Dan Hecht has posted comments on this change. Change subject: Allow compiler to use SSE3 and SSSE3 instructions. ......................................................................
Patch Set 2: > > > > Aren't these already on by default? I'm pretty sure impalad > > ends > > > > up with SSSE3 instructions. What's the default -march for > our > > > > toolchain gcc? > > > > > > I checked by using an SSE3 Intel Intrisic without adding this > > > compiler option. It caused the build to fail with "target > > specific > > > option mismatch" > > > > SSE3 shouldn't be enabled but SSSE3 might be. But it might not > be. > > > > However, what's the motivation for this change? Do you see a > > tangible benefit? We could do it, but there might be some Impala > > users out there running on AMD Bulldozer (2011) even though we > > technically require SSSE3. > > The purpose is to make byte shuffles and unaligned 16-byte SIMD > loads available for use with some of the SIMD optimizations that > are being done by the Intel contributors. I see. See IMPALA-1646 and IMPALA-1399 for some examples of CPUs that Impala would no longer run after making this change. While we never went back and claimed support for pre-SSSE3, it probably does work today. Could you check with Justin to make sure he's okay with really no longer working on these CPUs? -- To view, visit http://gerrit.cloudera.org:8080/3291 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-MessageType: comment Gerrit-Change-Id: Ib045e00b5aa71cc6ef16dbda160bfdc7b765158a Gerrit-PatchSet: 2 Gerrit-Project: Impala Gerrit-Branch: cdh5-trunk Gerrit-Owner: Jim Apple <[email protected]> Gerrit-Reviewer: Dan Hecht <[email protected]> Gerrit-Reviewer: Jim Apple <[email protected]> Gerrit-Reviewer: Tim Armstrong <[email protected]> Gerrit-HasComments: No
