From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Thread: 103376,cd86d70d109cd9b1 X-Google-Attributes: gid103376,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news2.google.com!news4.google.com!border1.nntp.dca.giganews.com!nntp.giganews.com!local01.nntp.dca.giganews.com!nntp.comcast.com!news.comcast.com.POSTED!not-for-mail NNTP-Posting-Date: Sat, 23 Dec 2006 00:50:50 -0600 From: tmoran@acm.org Newsgroups: comp.lang.ada Subject: Re: multicore-multithreading benchmarks References: X-Newsreader: Tom's custom newsreader Message-ID: Date: Sat, 23 Dec 2006 00:50:50 -0600 NNTP-Posting-Host: 67.164.83.70 X-Trace: sv3-jlqZ9ue5CPQl3w9vo5GWjkav1WhnoT/VNNR2ZW6Zdzi2h6C4IToTRNglw9fyL4jnU2oHVMHNqHC2U29!HBTOph6UkvoVlDQnC/1npVUNdL9asb3x/CXYv3+Qm+M3K/jocd9CsFbYsUQGZlnRw0DUkF/N5fGR!W9X3R/wUbIB3ng== X-Complaints-To: abuse@comcast.net X-DMCA-Complaints-To: dmca@comcast.net X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.32 Xref: g2news2.google.com comp.lang.ada:8000 Date: 2006-12-23T00:50:50-06:00 List-Id: >We can note that with N= 10000, 8 CPUs are often slightly slower in >Nyberg's; Alexander's; and my measurements (below) than 7 so-called >"CPUs", though this is not nearly as dramatic as the erratic timings The timings are short and thus highly subject to other things going on. Trysortn already does four runs and returns the average, but, especially when the "noise" is bursty, the result is still very erratic. The N=1000 case should probably be dropped since it's too fast for good timings, and too small for a multitasking advantage. Even N=10_000 is pretty small. It would be interesting though to see the results for N=10**7 since that ought to show some cache contention under multi-tasking. Thanks for posting the timings on your 4 core machine. They seem broadly in agreement on the value of additional CPUs/cores.