Commit 2159197d authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar

sched/core: Enable increased load resolution on 64-bit kernels

Mike ran into the low load resolution limitation on his big machine.

So reenable these bits; nobody could ever reproduce/analyze the
reported power usage claim and Google has been running with this for
years as well.
Reported-by: default avatarMike Galbraith <umgwanakikbuti@gmail.com>
Tested-by: default avatarMike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent e7904a28
...@@ -49,11 +49,13 @@ static inline void cpu_load_update_active(struct rq *this_rq) { } ...@@ -49,11 +49,13 @@ static inline void cpu_load_update_active(struct rq *this_rq) { }
* and does not change the user-interface for setting shares/weights. * and does not change the user-interface for setting shares/weights.
* *
* We increase resolution only if we have enough bits to allow this increased * We increase resolution only if we have enough bits to allow this increased
* resolution (i.e. BITS_PER_LONG > 32). The costs for increasing resolution * resolution (i.e. 64bit). The costs for increasing resolution when 32bit are
* when BITS_PER_LONG <= 32 are pretty high and the returns do not justify the * pretty high and the returns do not justify the increased costs.
* increased costs. *
* Really only required when CONFIG_FAIR_GROUP_SCHED is also set, but to
* increase coverage and consistency always enable it on 64bit platforms.
*/ */
#if 0 /* BITS_PER_LONG > 32 -- currently broken: it increases power usage under light load */ #ifdef CONFIG_64BIT
# define SCHED_LOAD_RESOLUTION 10 # define SCHED_LOAD_RESOLUTION 10
# define scale_load(w) ((w) << SCHED_LOAD_RESOLUTION) # define scale_load(w) ((w) << SCHED_LOAD_RESOLUTION)
# define scale_load_down(w) ((w) >> SCHED_LOAD_RESOLUTION) # define scale_load_down(w) ((w) >> SCHED_LOAD_RESOLUTION)
......
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