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authorPeter Zijlstra <peterz@infradead.org>2012-01-09 11:28:35 +0100
committerIngo Molnar <mingo@kernel.org>2012-05-17 13:48:56 +0200
commit8e7fbcbc22c12414bcc9dfdd683637f58fb32759 (patch)
treea438021ddeadddd8f0745293aeb8c80dbe3c999c /tools/power
parentfac536f7e4927f34d480dc066f3a578c743b8f0e (diff)
downloadvexpress-lsk-8e7fbcbc22c12414bcc9dfdd683637f58fb32759.tar.gz
sched: Remove stale power aware scheduling remnants and dysfunctional knobs
It's been broken forever (i.e. it's not scheduling in a power aware fashion), as reported by Suresh and others sending patches, and nobody cares enough to fix it properly ... so remove it to make space free for something better. There's various problems with the code as it stands today, first and foremost the user interface which is bound to topology levels and has multiple values per level. This results in a state explosion which the administrator or distro needs to master and almost nobody does. Furthermore large configuration state spaces aren't good, it means the thing doesn't just work right because it's either under so many impossibe to meet constraints, or even if there's an achievable state workloads have to be aware of it precisely and can never meet it for dynamic workloads. So pushing this kind of decision to user-space was a bad idea even with a single knob - it's exponentially worse with knobs on every node of the topology. There is a proposal to replace the user interface with a single 3 state knob: sched_balance_policy := { performance, power, auto } where 'auto' would be the preferred default which looks at things like Battery/AC mode and possible cpufreq state or whatever the hw exposes to show us power use expectations - but there's been no progress on it in the past many months. Aside from that, the actual implementation of the various knobs is known to be broken. There have been sporadic attempts at fixing things but these always stop short of reaching a mergable state. Therefore this wholesale removal with the hopes of spurring people who care to come forward once again and work on a coherent replacement. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Suresh Siddha <suresh.b.siddha@intel.com> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/1326104915.2442.53.camel@twins Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'tools/power')
-rw-r--r--tools/power/cpupower/man/cpupower-set.19
-rw-r--r--tools/power/cpupower/utils/helpers/sysfs.c35
2 files changed, 2 insertions, 42 deletions
diff --git a/tools/power/cpupower/man/cpupower-set.1 b/tools/power/cpupower/man/cpupower-set.1
index c4954a9fe4e..9dbd536518a 100644
--- a/tools/power/cpupower/man/cpupower-set.1
+++ b/tools/power/cpupower/man/cpupower-set.1
@@ -85,15 +85,6 @@ Possible values are:
savings
.RE
-sched_mc_power_savings is dependent upon SCHED_MC, which is
-itself architecture dependent.
-
-sched_smt_power_savings is dependent upon SCHED_SMT, which
-is itself architecture dependent.
-
-The two files are independent of each other. It is possible
-that one file may be present without the other.
-
.SH "SEE ALSO"
cpupower-info(1), cpupower-monitor(1), powertop(1)
.PP
diff --git a/tools/power/cpupower/utils/helpers/sysfs.c b/tools/power/cpupower/utils/helpers/sysfs.c
index c6343024a61..96e28c124b5 100644
--- a/tools/power/cpupower/utils/helpers/sysfs.c
+++ b/tools/power/cpupower/utils/helpers/sysfs.c
@@ -362,22 +362,7 @@ char *sysfs_get_cpuidle_driver(void)
*/
int sysfs_get_sched(const char *smt_mc)
{
- unsigned long value;
- char linebuf[MAX_LINE_LEN];
- char *endp;
- char path[SYSFS_PATH_MAX];
-
- if (strcmp("mc", smt_mc) && strcmp("smt", smt_mc))
- return -EINVAL;
-
- snprintf(path, sizeof(path),
- PATH_TO_CPU "sched_%s_power_savings", smt_mc);
- if (sysfs_read_file(path, linebuf, MAX_LINE_LEN) == 0)
- return -1;
- value = strtoul(linebuf, &endp, 0);
- if (endp == linebuf || errno == ERANGE)
- return -1;
- return value;
+ return -ENODEV;
}
/*
@@ -388,21 +373,5 @@ int sysfs_get_sched(const char *smt_mc)
*/
int sysfs_set_sched(const char *smt_mc, int val)
{
- char linebuf[MAX_LINE_LEN];
- char path[SYSFS_PATH_MAX];
- struct stat statbuf;
-
- if (strcmp("mc", smt_mc) && strcmp("smt", smt_mc))
- return -EINVAL;
-
- snprintf(path, sizeof(path),
- PATH_TO_CPU "sched_%s_power_savings", smt_mc);
- sprintf(linebuf, "%d", val);
-
- if (stat(path, &statbuf) != 0)
- return -ENODEV;
-
- if (sysfs_write_file(path, linebuf, MAX_LINE_LEN) == 0)
- return -1;
- return 0;
+ return -ENODEV;
}