mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-18 00:24:39 +00:00
6b8fcd9029
The ondemand cpufreq governor uses CPU busy time (e.g. not-idle time) as a measure for scaling the CPU frequency up or down. If the CPU is busy, the CPU frequency scales up, if it's idle, the CPU frequency scales down. Effectively, it uses the CPU busy time as proxy variable for the more nebulous "how critical is performance right now" question. This algorithm falls flat on its face in the light of workloads where you're alternatingly disk and CPU bound, such as the ever popular "git grep", but also things like startup of programs and maildir using email clients... much to the chagarin of Andrew Morton. This patch changes the ondemand algorithm to count iowait time as busy, not idle, time. As shown in the breakdown cases above, iowait is performance critical often, and by counting iowait, the proxy variable becomes a more accurate representation of the "how critical is performance" question. The problem and fix are both verified with the "perf timechar" tool. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Dave Jones <davej@redhat.com> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <20100509082606.3d9f00d0@infradead.org> Signed-off-by: Ingo Molnar <mingo@elte.hu> |
||
|---|---|---|
| .. | ||
| cpufreq.c | ||
| cpufreq_conservative.c | ||
| cpufreq_ondemand.c | ||
| cpufreq_performance.c | ||
| cpufreq_powersave.c | ||
| cpufreq_stats.c | ||
| cpufreq_userspace.c | ||
| freq_table.c | ||
| Kconfig | ||
| Makefile | ||