Bryce Harrington wrote: > On Sat, Oct 07, 2006 at 02:48:15PM +0200, Sebastien Godard wrote: > >> No, this is not really intended behavior. In fact sar is just not >> "hotplug CPU compliant" and has never been tested on such hardwares... >> Anyway I'm really interested to update it so that it can take into >> account CPU that get off- or onlined on the fly. But I need to know how >> files like /proc/stat for example are changed when a CPU is offlined or >> onlined. I would appreciate to get some info about that. >> > > Sure, I've attached two snapshots of /proc/stat, one with both cpu's > enabled, and one after a cpu has been disabled. This is on the EM64t > x86_64 machine. > > Thanks. To know exactly how things work, could you please do the following and then send me the various snapshots you got: 0) CPU's 0 and 1 online. 1) Take snapshot #1 of /proc/stat file 2) Disable CPU 1 3) Take snapshot #2 of /proc/stat 4) Wait a few (2-3...) seconds 5) Take snapshot #3 of /proc/stat 6) Enable CPU 1 7) Take snapshot #4 of /proc/stat Also could you tell me if there is a specific processor (for example CPU 0) that can *never* be disabled? (Indeed sar needs such a processor to compute the interval of time between two samples.) Regards, -- Sébastien Godard (sysstat <at> wanadoo.fr) http://perso.orange.fr/sebastien.godard/
