Hi all, this patch fixes an issue with the ondemand governor, which currently does not handle properly software coordinated CPUs - i.e. CPUs groups with a common clock and a single governor, as in the u8500: root@genericarmv7a:~# cpufreq-info -d DB8500 root@genericarmv7a:~# cpufreq-info -a 0 1 In this case, with a non-patched kernel, if a process is loading only the secondary CPU while the first one is idle, the ondemand governor may take a long time before firing up the load sampling routine (dbs_check_cpu()), leaving both cores running at minimum frequency even if one of them is fully loaded. The problem can be reproduced with standard utils, as in: root@genericarmv7a:~# cpufreq-info --cpu 1 -f 200000 root@genericarmv7a:~# taskset 2 yes > /dev/null & root@genericarmv7a:~# sleep 3 root@genericarmv7a:~# cpufreq-info --cpu 1 -f 200000 while there is no other process loading the other core - here I'm using a minimal oe-core image. To fix the problem, this patch modifies the governor to use an individual deferrable work for each CPU, instead that just one for the main one. This patch has been tested on an U8500 system (dual cortex-A9) and on a standard x86_64 dual-core laptop. The patch is based on the original one by Rickard Andersson, developed for ST-Ericsson and posted some months ago on the list, hence I'm tagging as "v3" to avoid confusion. Regards, Fabio --- Rickard Andersson (1): cpufreq: ondemand: handle SW coordinated CPUs drivers/cpufreq/cpufreq_ondemand.c | 141 ++++++++++++++++++++++++++++++++----- 1 file changed, 122 insertions(+), 19 deletions(-) -- 1.7.12.1 -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
