Messages in this thread | | | Date | Wed, 17 Dec 2008 23:40:33 +0530 | From | Balbir Singh <> | Subject | Re: [PATCH v6 1/7] sched: Framework for sched_mc/smt_power_savings=N |
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* Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> [2008-12-17 22:56:35]:
> From: Gautham R Shenoy <ego@in.ibm.com> > > Currently the sched_mc/smt_power_savings variable is a boolean, > which either enables or disables topology based power savings. > This patch extends the behaviour of the variable from boolean to > multivalued, such that based on the value, we decide how > aggressively do we want to perform powersavings balance at > appropriate sched domain based on topology. > > Variable levels of power saving tunable would benefit end user to > match the required level of power savings vs performance > trade-off depending on the system configuration and workloads. > > This version makes the sched_mc_power_savings global variable to > take more values (0,1,2). Later versions can have a single > tunable called sched_power_savings instead of > sched_{mc,smt}_power_savings. > > Signed-off-by: Gautham R Shenoy <ego@in.ibm.com> > Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> > --- > > include/linux/sched.h | 11 +++++++++++ > kernel/sched.c | 17 ++++++++++++++--- > 2 files changed, 25 insertions(+), 3 deletions(-) > > diff --git a/include/linux/sched.h b/include/linux/sched.h > index 55e30d1..888f2b2 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -764,6 +764,17 @@ enum cpu_idle_type { > #define SD_SERIALIZE 1024 /* Only a single load balancing instance */ > #define SD_WAKE_IDLE_FAR 2048 /* Gain latency sacrificing cache hit */ > > +enum powersavings_balance_level { > + POWERSAVINGS_BALANCE_NONE = 0, /* No power saving load balance */ > + POWERSAVINGS_BALANCE_BASIC, /* Fill one thread/core/package > + * first for long running threads > + */ > + POWERSAVINGS_BALANCE_WAKEUP, /* Also bias task wakeups to semi-idle > + * cpu package for power savings > + */ > + MAX_POWERSAVINGS_BALANCE_LEVELS > +}; > + > #define BALANCE_FOR_MC_POWER \ > (sched_smt_power_savings ? SD_POWERSAVINGS_BALANCE : 0) > > diff --git a/kernel/sched.c b/kernel/sched.c > index e4bb1dd..16897ab 100644 > --- a/kernel/sched.c > +++ b/kernel/sched.c > @@ -7879,14 +7879,25 @@ int arch_reinit_sched_domains(void) > static ssize_t sched_power_savings_store(const char *buf, size_t count, int smt) > { > int ret; > + unsigned int level = 0; > > - if (buf[0] != '0' && buf[0] != '1') > + if (sscanf(buf, "%u", &level) != 1) > + return -EINVAL; > + > + /* > + * level is always be positive so don't check for > + * level < POWERSAVINGS_BALANCE_NONE which is 0 > + * What happens on 0 or 1 byte write, > + * need to check for count as well? > + */ > + > + if (level >= MAX_POWERSAVINGS_BALANCE_LEVELS) > return -EINVAL; > > if (smt) > - sched_smt_power_savings = (buf[0] == '1'); > + sched_smt_power_savings = level; > else > - sched_mc_power_savings = (buf[0] == '1'); > + sched_mc_power_savings = level; > > ret = arch_reinit_sched_domains(); >
Looks good to me
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
-- Balbir
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