On Thursday 01 April 2010 18:24:08 ext Manjunatha GK wrote: > From: DebBarma, Tarun Kanti <[email protected]> > > [ARM Cortex-A8 Errata 628216] > If a Perf Counter OVFL occurs simultaneously with an update to a CP14 or > CP15 register, the OVFL status can be lost. > > In order to workaround problem in Cortex-A8 Performance Counter, OMAP > GPTIMER is used by OProfile.
Thanks for digging this up. But even though GPTIMER has a lower overhead, there is actually a better (more portable) fix which is on the way into mainline kernel: http://marc.info/?l=oprofile-list&m=126754919315010&w=2 Samples collection frequency can be adjusted by another patch (the default 128Hz used on most ARM boards/devices is way too low). oprofile kernel module can be loaded with 'timer=1' parameter to override the use of buggy Cortex-A8 PMU. -- Best regards, Siarhei Siamashka -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
