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Message-ID: <56f3abef-439d-41e3-9ad6-44adca01eeb0@amd.com> Date: Mon, 21 Oct 2024 12:09:30 -0500 From: "Moger, Babu" <babu.moger@....com> To: Reinette Chatre <reinette.chatre@...el.com>, corbet@....net, fenghua.yu@...el.com, tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com Cc: x86@...nel.org, hpa@...or.com, paulmck@...nel.org, rdunlap@...radead.org, tj@...nel.org, peterz@...radead.org, yanjiewtw@...il.com, kim.phillips@....com, lukas.bulwahn@...il.com, seanjc@...gle.com, jmattson@...gle.com, leitao@...ian.org, jpoimboe@...nel.org, rick.p.edgecombe@...el.com, kirill.shutemov@...ux.intel.com, jithu.joseph@...el.com, kai.huang@...el.com, kan.liang@...ux.intel.com, daniel.sneddon@...ux.intel.com, pbonzini@...hat.com, sandipan.das@....com, ilpo.jarvinen@...ux.intel.com, peternewman@...gle.com, maciej.wieczor-retman@...el.com, linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, eranian@...gle.com, james.morse@....com Subject: Re: [PATCH v8 00/25] x86/resctrl : Support AMD Assignable Bandwidth Monitoring Counters (ABMC) Hi Reinette, Thanks again for quick turn around for this series. Will start working on v9. On 10/15/24 22:05, Reinette Chatre wrote: > Hi Babu, > > On 10/9/24 10:39 AM, Babu Moger wrote: >> >> This series adds the support for Assignable Bandwidth Monitoring Counters >> (ABMC). It is also called QoS RMID Pinning feature >> >> Series is written such that it is easier to support other assignable >> features supported from different vendors. >> >> The feature details are documented in the APM listed below [1]. >> [1] AMD64 Architecture Programmer's Manual Volume 2: System Programming >> Publication # 24593 Revision 3.41 section 19.3.3.3 Assignable Bandwidth >> Monitoring (ABMC). The documentation is available at >> Link: https://bugzilla.kernel.org/show_bug.cgi?id=206537 >> >> The patches are based on top of commit >> 5b0c5f05fb2fe (tip/master) Merge branch into tip/master: 'x86/splitlock' >> >> # Introduction >> >> Users can create as many monitor groups as RMIDs supported by the hardware. >> However, bandwidth monitoring feature on AMD system only guarantees that >> RMIDs currently assigned to a processor will be tracked by hardware. >> The counters of any other RMIDs which are no longer being tracked will be >> reset to zero. The MBM event counters return "Unavailable" for the RMIDs >> that are not tracked by hardware. So, there can be only limited number of >> groups that can give guaranteed monitoring numbers. With ever changing >> configurations there is no way to definitely know which of these groups >> are being tracked for certain point of time. Users do not have the option >> to monitor a group or set of groups for certain period of time without >> worrying about RMID being reset in between. > > "worrying about RMID being reset in between" -> "worrying about counter being > reset in between"? Sure, > >> >> The ABMC feature provides an option to the user to assign a hardware >> counter to an RMID, event pair and monitor the bandwidth as long as it is >> assigned. The assigned RMID will be tracked by the hardware until the user >> unassigns it manually. There is no need to worry about counters being reset >> during this period. Additionally, the user can specify a bitmask identifying >> the specific bandwidth types from the given source to track with the counter. >> >> Without ABMC enabled, monitoring will work in current 'default' mode without >> assignment option. >> > > Reinette > -- Thanks Babu Moger
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