On Fri, 21 Feb 2025 16:54:40 +0000 Chris MacNamara <chris.macnam...@intel.com> wrote:
> A recent CPU change requires an extra enabling step for > the umonitor instruction on Intel CPUs. > This is now detailed in the l3 fwd power manager doc. > > Signed-off-by: Chris MacNamara <chris.macnam...@intel.com> > --- > .mailmap | 1 + > doc/guides/sample_app_ug/l3_forward_power_man.rst | 5 +++++ > 2 files changed, 6 insertions(+) > > diff --git a/.mailmap b/.mailmap > index a03d3cfb59..c4bc38752f 100644 > --- a/.mailmap > +++ b/.mailmap > @@ -263,6 +263,7 @@ Christopher Reder <christopher.re...@broadcom.com> > Christoph Gysin <christoph.gy...@gmail.com> > Christos Ricudis <ricu...@niometrics.com> > Chris Wright <chr...@redhat.com> > +Chris MacNamara <chris.macnam...@intel.com> > Chuanshe Zhang <zhangchuan...@icloudshield.com> > Chuanyu Xue <chuanyu....@uconn.edu> > Chuhong Yao <y...@panath.cn> > diff --git a/doc/guides/sample_app_ug/l3_forward_power_man.rst > b/doc/guides/sample_app_ug/l3_forward_power_man.rst > index 3271bc2154..d0af28e0ec 100644 > --- a/doc/guides/sample_app_ug/l3_forward_power_man.rst > +++ b/doc/guides/sample_app_ug/l3_forward_power_man.rst > @@ -293,6 +293,11 @@ and has three available power management schemes: > ``monitor`` > This will use ``rte_power_monitor()`` function to enter > a power-optimized state (subject to platform support). > + On recent Gen 4 Xeon Scalable Processors the umonitor instruction > + is disabled by default. > + An additional step is required to enable the umonitor instruction. > + Writing 0 to bit 6 of register 0x123 will enable umonitor. > + `More details are available via Monitor and Umonitor Performance Guidance > <https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/technical-documentation/monitor-umonitor-performance-guidance.html>`_ > This should be done by the power library, what is the point of having a power API if we require applications to test for CPU type and go tweak some CPU register bits. And it may be restricted by OS permissions etc.
