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hwpstate_intel: Use 8bit scale instead of percentage scale

Browse Source 
Reviewed by:    olce
Relnotes:       yes
Event:          Halifax Hackathon 202606
Sponsored by:   The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D55629
This commit is contained in:
ShengYi Hung committed 2026-06-25 02:18:20 +08:00
1 parent 3a5c2899fc
commit 8452afeb56
2 files changed
+14 -63
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share/man/man4/hwpstate_intel.4
+3 -3
View File
@@ -22,7 +22,7 @@
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.Dd April 21, 2020
.Dd June 24, 2026
.Dt HWPSTATE_INTEL 4
.Os
.Sh NAME
@@ -75,9 +75,9 @@ For example
.It dev.hwpstate_intel.0.%parent: cpu0
.It Va dev.hwpstate_intel.%d.epp
Energy/Performance Preference.
Valid values range from 0 to 100.
Valid values range from 0 to 255.
Setting this field conveys a hint to the hardware regarding a preference towards
performance (at value 0), energy efficiency (at value 100), or somewhere in
performance (at value 0), energy efficiency (at value 255), or somewhere in
between.
.It dev.hwpstate_intel.0.epp: 0
.El
sys/x86/cpufreq/hwpstate_intel.c
+11 -60
View File
@@ -254,53 +254,8 @@ out:
return (ret);
}
static inline int
percent_to_raw(int x)
{
MPASS(x <= 100 && x >= 0);
return (0xff * x / 100);
}
/*
* Given x * 10 in [0, 1000], round to the integer nearest x.
*
* This allows round-tripping nice human readable numbers through this
* interface. Otherwise, user-provided percentages such as 25, 50, 75 get
* rounded down to 24, 49, and 74, which is a bit ugly.
*/
static inline int
round10(int xtimes10)
{
return ((xtimes10 + 5) / 10);
}
static inline int
raw_to_percent(int x)
{
MPASS(x <= 0xff && x >= 0);
return (round10(x * 1000 / 0xff));
}
/* Range of MSR_IA32_ENERGY_PERF_BIAS is more limited: 0-0xf. */
static inline int
percent_to_raw_perf_bias(int x)
{
/*
* Round up so that raw values present as nice round human numbers and
* also round-trip to the same raw value.
*/
MPASS(x <= 100 && x >= 0);
return (((0xf * x) + 50) / 100);
}
static inline int
raw_to_percent_perf_bias(int x)
{
/* Rounding to nice human numbers despite a step interval of 6.67%. */
MPASS(x <= 0xf && x >= 0);
return (((x * 20) / 0xf) * 5);
}
#define EPB_TO_EPP(x) ((x) * 17)
#define EPP_TO_EPB(x) ((x) >> 4)
static int
sysctl_epp_select(SYSCTL_HANDLER_ARGS)
@@ -310,7 +265,6 @@ sysctl_epp_select(SYSCTL_HANDLER_ARGS)
struct pcpu *pc;
uint64_t epb;
uint32_t val;
uint64_t req_cached;
int ret;
dev = oidp->oid_arg1;
@@ -324,7 +278,6 @@ sysctl_epp_select(SYSCTL_HANDLER_ARGS)
if (sc->hwp_pref_ctrl) {
val = (sc->req & IA32_HWP_REQUEST_ENERGY_PERFORMANCE_PREFERENCE) >> 24;
val = raw_to_percent(val);
} else {
/*
* If cpuid indicates EPP is not supported, the HWP controller
@@ -341,35 +294,33 @@ sysctl_epp_select(SYSCTL_HANDLER_ARGS)
}
val = sc->hwp_energy_perf_bias &
IA32_ENERGY_PERF_BIAS_POLICY_HINT_MASK;
val = raw_to_percent_perf_bias(val);
val = EPB_TO_EPP(val);
}
MPASS(val >= 0 && val <= 100);
MPASS(val >= 0 && val <= 255);
ret = sysctl_handle_int(oidp, &val, 0, req);
if (ret || req->newptr == NULL)
goto out;
if (val > 100) {
if (val > 255 || val < 0) {
ret = EINVAL;
goto out;
}
if (sc->hwp_pref_ctrl) {
val = percent_to_raw(val);
req_cached = sc->req =
((sc->req &
~IA32_HWP_REQUEST_ENERGY_PERFORMANCE_PREFERENCE) |
(val << 24u));
sc->req =
((sc->req & ~IA32_HWP_REQUEST_ENERGY_PERFORMANCE_PREFERENCE)
| (val << 24u));
if (sc->hwp_pkg_ctrl_en)
ret = WRMSR_ON_CPU(dev, MSR_IA32_HWP_REQUEST_PKG,
req_cached);
sc->req);
else
ret = WRMSR_ON_CPU(dev, MSR_IA32_HWP_REQUEST,
req_cached);
sc->req);
} else {
val = percent_to_raw_perf_bias(val);
val = EPP_TO_EPB(val);
MPASS((val & ~IA32_ENERGY_PERF_BIAS_POLICY_HINT_MASK) == 0);
sc->hwp_energy_perf_bias =