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authorGautham R Shenoy <ego@in.ibm.com>2008-12-18 23:26:09 +0530
committerIngo Molnar <mingo@elte.hu>2008-12-19 09:21:46 +0100
commitafb8a9b70b86866a60e08b2956ae4e1406390336 (patch)
treee4f8918230f4a4eb696c32edb888bced183001db /kernel/sched.c
parent716707b29906e1d8d190defe3d646610b097a861 (diff)
sched: framework for sched_mc/smt_power_savings=N
Impact: extend range of /sys/devices/system/cpu/sched_mc_power_savings 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> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sched.c')
-rw-r--r--kernel/sched.c17
1 files changed, 14 insertions, 3 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index b309027bf9e..56b285cd535 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -7906,14 +7906,25 @@ 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();