Srinivas Pandruvada <srinivas.pandruv...@linux.intel.com> writes: > Enable HWP boost on Skylake server and workstations. >
Please revert this series, it led to significant energy usage and graphics performance regressions [1]. The reasons are roughly the ones we discussed by e-mail off-list last April: This causes the intel_pstate driver to decrease the EPP to zero when the workload blocks on IO frequently enough, which for the regressing benchmarks detailed in [1] is a symptom of the workload being heavily IO-bound, which means they won't benefit at all from the EPP boost since they aren't significantly CPU-bound, and they will suffer a decrease in parallelism due to the active CPU core using a larger fraction of the TDP in order to achieve the same work, causing the GPU to have a lower power budget available, leading to a decrease in system performance. You may want to give a shot to my previous suggestion of using [2] in order to detect whether the system is IO-bound, which you can use as an indicator that the optimization implemented in this series cannot possibly improve performance and can be expected to hurt energy usage. Thanks. [1] https://bugs.freedesktop.org/show_bug.cgi?id=107410 [2] https://patchwork.kernel.org/patch/10312259/ > Reported-by: Mel Gorman <mgor...@techsingularity.net> > Tested-by: Giovanni Gherdovich <ggherdov...@suse.cz> > Signed-off-by: Srinivas Pandruvada <srinivas.pandruv...@linux.intel.com> > --- > drivers/cpufreq/intel_pstate.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c > index 70bf63bb4e0e..01c8da1f99db 100644 > --- a/drivers/cpufreq/intel_pstate.c > +++ b/drivers/cpufreq/intel_pstate.c > @@ -1794,6 +1794,12 @@ static const struct x86_cpu_id > intel_pstate_cpu_ee_disable_ids[] = { > {} > }; > > +static const struct x86_cpu_id intel_pstate_hwp_boost_ids[] __initconst = { > + ICPU(INTEL_FAM6_SKYLAKE_X, core_funcs), > + ICPU(INTEL_FAM6_SKYLAKE_DESKTOP, core_funcs), > + {} > +}; > + > static int intel_pstate_init_cpu(unsigned int cpunum) > { > struct cpudata *cpu; > @@ -1824,6 +1830,10 @@ static int intel_pstate_init_cpu(unsigned int cpunum) > intel_pstate_disable_ee(cpunum); > > intel_pstate_hwp_enable(cpu); > + > + id = x86_match_cpu(intel_pstate_hwp_boost_ids); > + if (id) > + hwp_boost = true; > } > > intel_pstate_get_cpu_pstates(cpu); > -- > 2.13.6
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