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)); _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "[email protected]"
