svn commit: r323286 - head/sys/x86/cpufreq
Conrad Meyer
cem at FreeBSD.org
Thu Sep 7 20:20:14 UTC 2017
Author: cem
Date: Thu Sep 7 20:20:12 2017
New Revision: 323286
URL: https://svnweb.freebsd.org/changeset/base/323286
Log:
cpufreq(4) hwpstate: Yield CPU awaiting frequency change
It doesn't seem necessary to busy the CPU while waiting to transition
into a different p-state.
PR: 221621 (related, but does not completely address)
Reviewed by: truckman
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D12260
Modified:
head/sys/x86/cpufreq/hwpstate.c
Modified: head/sys/x86/cpufreq/hwpstate.c
==============================================================================
--- head/sys/x86/cpufreq/hwpstate.c Thu Sep 7 20:18:57 2017 (r323285)
+++ head/sys/x86/cpufreq/hwpstate.c Thu Sep 7 20:20:12 2017 (r323286)
@@ -160,6 +160,7 @@ DRIVER_MODULE(hwpstate, cpu, hwpstate_driver, hwpstate
static int
hwpstate_goto_pstate(device_t dev, int pstate)
{
+ sbintime_t sbt;
int i;
uint64_t msr;
int j;
@@ -170,7 +171,7 @@ hwpstate_goto_pstate(device_t dev, int pstate)
/* get the current pstate limit */
msr = rdmsr(MSR_AMD_10H_11H_LIMIT);
limit = AMD_10H_11H_GET_PSTATE_LIMIT(msr);
- if(limit > id)
+ if (limit > id)
id = limit;
/*
@@ -184,7 +185,7 @@ hwpstate_goto_pstate(device_t dev, int pstate)
sched_bind(curthread, i);
thread_unlock(curthread);
HWPSTATE_DEBUG(dev, "setting P%d-state on cpu%d\n",
- id, PCPU_GET(cpuid));
+ id, PCPU_GET(cpuid));
/* Go To Px-state */
wrmsr(MSR_AMD_10H_11H_CONTROL, id);
}
@@ -194,13 +195,14 @@ hwpstate_goto_pstate(device_t dev, int pstate)
sched_bind(curthread, i);
thread_unlock(curthread);
/* wait loop (100*100 usec is enough ?) */
- for(j = 0; j < 100; j++){
+ for (j = 0; j < 100; j++){
/* get the result. not assure msr=id */
msr = rdmsr(MSR_AMD_10H_11H_STATUS);
- if(msr == id){
+ if (msr == id)
break;
- }
- DELAY(100);
+ sbt = SBT_1MS / 10;
+ tsleep_sbt(dev, PZERO, "pstate_goto", sbt,
+ sbt >> tc_precexp, 0);
}
HWPSTATE_DEBUG(dev, "result: P%d-state on cpu%d\n",
(int)msr, PCPU_GET(cpuid));
More information about the svn-src-all
mailing list