Michael Ho has posted comments on this change. Change subject: IMPALA-3286: Software prefetching for hash table build. ......................................................................
Patch Set 8: (2 comments) http://gerrit.cloudera.org:8080/#/c/2896/8/be/src/exec/hash-table.h File be/src/exec/hash-table.h: Line 545: HashTable* table_; > let's add: Done http://gerrit.cloudera.org:8080/#/c/2896/8/be/src/exec/hash-table.inline.h File be/src/exec/hash-table.inline.h: Line 131: 1 > how did you pick this? I think the prefetch level maps to instructions prefetch{0-2} and prefetchnta, with prefetch0 being the one which populates all the cache levels and prefetch2 being the one which populates the L3 cache only. Given the size of the hash table, I think it's safer to just keep it in LLC instead of polluting the upper level caches. I compared the build time with a self-join of lineitem with 1-3 and the difference is within the noise. -- To view, visit http://gerrit.cloudera.org:8080/2896 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-MessageType: comment Gerrit-Change-Id: Ib85e7fc162ad25c849b9e716b629e226697cd940 Gerrit-PatchSet: 8 Gerrit-Project: Impala Gerrit-Branch: cdh5-trunk Gerrit-Owner: Michael Ho <[email protected]> Gerrit-Reviewer: Dan Hecht <[email protected]> Gerrit-Reviewer: Marcel Kornacker <[email protected]> Gerrit-Reviewer: Michael Ho <[email protected]> Gerrit-Reviewer: Mostafa Mokhtar <[email protected]> Gerrit-Reviewer: Tim Armstrong <[email protected]> Gerrit-HasComments: Yes
