{"id":1146,"date":"2011-02-11T15:48:33","date_gmt":"2011-02-11T13:48:33","guid":{"rendered":"http:\/\/oldblogs.uct.ac.za\/blog\/big-bytes\/2011\/02\/11\/a-stressful-day"},"modified":"2015-08-14T14:08:24","modified_gmt":"2015-08-14T12:08:24","slug":"a-stressful-day","status":"publish","type":"post","link":"https:\/\/ucthpc.uct.ac.za\/index.php\/2011\/02\/11\/a-stressful-day\/","title":{"rendered":"A stressful day"},"content":{"rendered":"Patched kernels on HPC servers to 2.6.18-238.1.1.el5; All went fine except for the head node which has an issue with latest kernel (dies at boot with a kernel panic) so booting it into older version 2.6.18-194.1.1.el5 until we can sort this out.\r\n\r\nFixed an issue with openmpi on grid cluster - usual problem with openmpi.conf looking for Infiniband\r\n\r\nInvestigated unexpected computation speeds for differing chips with MPI.\u00a0 Slower CPU cores were completing jobs in less time than faster CPUs however this seems to boil down to the nature of the jobs, large array computations, the size of the CPU cache and the communication latency between parallel processes.\r\n\r\nSome interesting links to Intel CPU types:\r\n<a href=\"http:\/\/en.wikipedia.org\/wiki\/List_of_Intel_microprocessors\">List_of_Intel_microprocessors<\/a>\r\n<a href=\"http:\/\/en.wikipedia.org\/wiki\/Comparison_of_Intel_processors\">Comparison_of_Intel_processors<\/a>\r\n<a href=\"http:\/\/en.wikipedia.org\/wiki\/Intel_Core\">Intel_Cores<\/a>\r\n\r\n&nbsp;","protected":false},"excerpt":{"rendered":"<p>    Patched kernels on HPC servers to 2.6.18-238.1.1.el5; All went fine except for the head node which has an issue with latest kernel (dies at boot with a kernel panic) so booting it into older version 2.6.18-194.1.1.el5 until we can sort this out.Fi&#8230;<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[6,4,10,11],"tags":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v21.4 - 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