>Number: 144232
>Category: kern
>Synopsis: [PATCH] Add debug.cpufreq.highest to cpufreq
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: change-request
>Submitter-Id: current-users
>Arrival-Date: Tue Feb 23 14:40:00 UTC 2010
>Closed-Date:
>Last-Modified:
>Originator: Boris Kochergin
>Release: 8.0-RELEASE-p2
>Organization:
Polytechnic Institute of NYU
>Environment:
FreeBSD peer 8.0-RELEASE-p2 FreeBSD 8.0-RELEASE-p2 #2: Mon Feb 22 23:18:53 EST
2010 r...@peer:/usr/obj/usr/src/sys/PEER i386
>Description:
I request that support for the debug.cpufreq.highest sysctl, which places an
upper bound on the frequencies returned to users, be added to cpufreq. I am
currently using it in conjunction with the dev.acpi_ibm.0.fan_level sysctl from
the acpi_ibm module set to 0 to keep a laptop both cool and quiet while it has
a broken fan. Others have also found uses for the functionality
(http://forums.freebsd.org/showthread.php?t=172).
>How-To-Repeat:
>Fix:
Patch attached with submission follows:
--- sys/kern/kern_cpu.c.orig 2010-02-22 22:40:37.000000000 -0500
+++ sys/kern/kern_cpu.c 2010-02-22 23:11:03.000000000 -0500
@@ -131,12 +131,16 @@
DRIVER_MODULE(cpufreq, cpu, cpufreq_driver, cpufreq_dc, 0, 0);
static int cf_lowest_freq;
+static int cf_highest_freq;
static int cf_verbose;
TUNABLE_INT("debug.cpufreq.lowest", &cf_lowest_freq);
+TUNABLE_INT("debug.cpufreq.highest", &cf_highest_freq);
TUNABLE_INT("debug.cpufreq.verbose", &cf_verbose);
SYSCTL_NODE(_debug, OID_AUTO, cpufreq, CTLFLAG_RD, NULL, "cpufreq debugging");
SYSCTL_INT(_debug_cpufreq, OID_AUTO, lowest, CTLFLAG_RW, &cf_lowest_freq, 1,
"Don't provide levels below this frequency.");
+SYSCTL_INT(_debug_cpufreq, OID_AUTO, highest, CTLFLAG_RW, &cf_highest_freq, 1,
+ "Don't provide levels above this frequency.");
SYSCTL_INT(_debug_cpufreq, OID_AUTO, verbose, CTLFLAG_RW, &cf_verbose, 1,
"Print verbose debugging messages");
@@ -306,6 +310,14 @@
goto out;
}
+ /* Reject levels that are above our specified threshold. */
+ if (cf_highest_freq > 0 && level->total_set.freq > cf_highest_freq) {
+ CF_DEBUG("rejecting freq %d, greater than %d limit\n",
+ level->total_set.freq, cf_highest_freq);
+ error = EINVAL;
+ goto out;
+ }
+
/* If already at this level, just return. */
if (CPUFREQ_CMP(sc->curr_level.total_set.freq, level->total_set.freq)) {
CF_DEBUG("skipping freq %d, same as current level %d\n",
@@ -633,8 +645,13 @@
continue;
}
- /* Skip levels that have a frequency that is too low. */
- if (lev->total_set.freq < cf_lowest_freq) {
+ /*
+ * Skip levels that have a frequency that is too low or too
+ * high.
+ */
+ if (lev->total_set.freq < cf_lowest_freq ||
+ (cf_highest_freq > 0 &&
+ lev->total_set.freq > cf_highest_freq)) {
sc->all_count--;
continue;
}
--- share/man/man4/cpufreq.4.orig 2010-02-23 09:24:45.000000000 -0500
+++ share/man/man4/cpufreq.4 2010-02-23 09:25:59.000000000 -0500
@@ -98,6 +98,11 @@
This setting is also accessible via a tunable with the same name.
This can be used to disable very low levels that may be unusable on
some systems.
+.It Va debug.cpufreq.highest
+Highest CPU frequency in MHz to offer to users.
+This setting is also accessible via a tunable with the same name.
+This can be used to disable very high levels that may be unusable on
+some systems.
.It Va debug.cpufreq.verbose
Print verbose messages.
This setting is also accessible via a tunable with the same name.
>Release-Note:
>Audit-Trail:
>Unformatted:
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