> On 28.12.2011 14:03, Tatsuo Ishii wrote: >>>> With help from IBM Japan Ltd. we did some tests on a larger IBM >>>> machine than Tom Lane has used for his >>>> test(http://archives.postgresql.org/message-id/8292.1314641...@sss.pgh.pa.us). >>>> In his case it was IBM 8406-71Y, which has 8 physical cores and >>>> 4SMT(32 threadings). Ours is IBM Power 750 Express, which has 32 >>>> physical cores and 4SMT(128 threadings), 256GB RAM. >>>> >>>> The test method was same as the one in the article above. The >>>> differences are OS(RHEL 6.1), gcc version (4.4.5) and shared buffer >>>> size(8GB). >>>> >>>> We tested 3 methods to enhance spin lock contention: >>>> >>>> 1) Add "hint" parameter to lwarx op which is usable POWER6 or later >>>> architecure. >>>> >>>> 2) Add non-locked test in TAS() >>>> >>>> 3) #1 + #2 >>>> >>>> We saw small performance enhancement with #1, larger one with #2 and >>>> even better with #1+#2. >>> >>> Hmm, so you added the non-locked test in TAS()? Did you try adding it >>> just to TAS_SPIN()? On Itanium, I found that it was slightly better >>> to do it only in TAS_SPIN() - i.e. in the contended case. >> >> Here is new patch using TAS_SPIN(), created by Manabu Ori from IBM >> Japan. Also this patch deal with older Power architectures which do >> not have "hint" argument of lwarx opcode. >> >> According to him, the patch resulted in much better performance stock >> git head. > > Impressive results. > > config/c-compiler.m4 doesn't seem like the right place for the > configure test. Would there be any harm in setting the lwarx hint > always; what would happen on older ppc processors that don't support > it?
I think the load module just fails to run in this case, but I'd like to confirm. Ori-san? -- Tatsuo Ishii SRA OSS, Inc. Japan English: http://www.sraoss.co.jp/index_en.php Japanese: http://www.sraoss.co.jp -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
