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Message-ID: <0c2f9239-2299-4316-a375-a417f61a8238@amd.com> Date: Tue, 15 Apr 2025 10:00:51 -0500 From: "Moger, Babu" <babu.moger@....com> To: Reinette Chatre <reinette.chatre@...el.com>, tony.luck@...el.com, peternewman@...gle.com Cc: corbet@....net, tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com, paulmck@...nel.org, akpm@...ux-foundation.org, thuth@...hat.com, rostedt@...dmis.org, ardb@...nel.org, gregkh@...uxfoundation.org, daniel.sneddon@...ux.intel.com, jpoimboe@...nel.org, alexandre.chartre@...cle.com, pawan.kumar.gupta@...ux.intel.com, thomas.lendacky@....com, perry.yuan@....com, seanjc@...gle.com, kai.huang@...el.com, xiaoyao.li@...el.com, kan.liang@...ux.intel.com, xin3.li@...el.com, ebiggers@...gle.com, xin@...or.com, sohil.mehta@...el.com, andrew.cooper3@...rix.com, mario.limonciello@....com, linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, maciej.wieczor-retman@...el.com, eranian@...gle.com Subject: Re: [PATCH v12 16/26] x86/resctrl: Report 'Unassigned' for MBM events in mbm_cntr_assign mode Hi Reinette, On 4/11/25 16:08, Reinette Chatre wrote: > Hi Babu, > > On 4/3/25 5:18 PM, Babu Moger wrote: >> In mbm_cntr_assign mode, the hardware counter should be assigned to read >> the MBM events. >> >> Report 'Unassigned' in case the user attempts to read the events without > > "the events" -> "the event"? Sure. > >> assigning the counter. > > "the counter" -> "a hardware counter"? > Sure. >> >> Signed-off-by: Babu Moger <babu.moger@....com> >> --- > ... > >> --- >> Documentation/arch/x86/resctrl.rst | 10 ++++++++++ >> arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 14 ++++++++++++++ >> arch/x86/kernel/cpu/resctrl/internal.h | 3 +++ >> arch/x86/kernel/cpu/resctrl/monitor.c | 4 ++-- >> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 2 +- >> 5 files changed, 30 insertions(+), 3 deletions(-) >> >> diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst >> index 44128fbda4fe..71ed1cfed33a 100644 >> --- a/Documentation/arch/x86/resctrl.rst >> +++ b/Documentation/arch/x86/resctrl.rst >> @@ -430,6 +430,16 @@ When monitoring is enabled all MON groups will also contain: >> for the L3 cache they occupy). These are named "mon_sub_L3_YY" >> where "YY" is the node number. >> >> + The mbm_cntr_assign mode offers "num_mbm_cntrs" number of counters >> + and allows users to assign a counter to mon_hw_id, event pair enabling >> + bandwidth monitoring for as long as the counter remains assigned. >> + The hardware will continue tracking the assigned mon_hw_id until >> + the user manually unassigns it, ensuring that counters are not reset >> + during this period. System may run out of assignable counters when >> + all the counters are already assigned. In that case, MBM event counters > > Counters could be unassigned even if there are assignable counters available. > > I think the "System may run ..." sentence should be dropped. > The "In that case ..." sentence could be simplified with something like: > "An MBM event returns 'Unassigned' when the event does not have a hardware > counter assigned." > Sure. >> + will return 'Unassigned' when the event is read. Users must manually >> + assign a counter to read the events. >> + >> "mon_hw_id": >> Available only with debug option. The identifier used by hardware >> for the monitor group. On x86 this is the RMID. > > Reinette > > -- Thanks Babu Moger
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