Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752737AbcD2V0R (ORCPT ); Fri, 29 Apr 2016 17:26:17 -0400 Received: from mail-vk0-f49.google.com ([209.85.213.49]:33236 "EHLO mail-vk0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752634AbcD2V0P (ORCPT ); Fri, 29 Apr 2016 17:26:15 -0400 MIME-Version: 1.0 In-Reply-To: References: <1461905018-86355-1-git-send-email-davidcc@google.com> <1461905018-86355-27-git-send-email-davidcc@google.com> Date: Fri, 29 Apr 2016 14:26:13 -0700 Message-ID: Subject: Re: [PATCH 26/32] perf/x86/intel/cqm: integrate CQM cgroups with scheduler From: David Carrillo-Cisneros To: Vikas Shivappa Cc: Peter Zijlstra , Alexander Shishkin , Arnaldo Carvalho de Melo , Ingo Molnar , Tony Luck , Stephane Eranian , Paul Turner , x86@kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 12958 Lines: 366 if __intel_cqm_no_event_sched_in does nothing, the PQR_ASSOC msr is still updated if state->rmid != state->next_rmid in __pqr_update, even if next_rmid_mode == PQR_RMID_MODE_NOEVENT . On Fri, Apr 29, 2016 at 2:01 PM, Vikas Shivappa wrote: > > > On Fri, 29 Apr 2016, David Carrillo-Cisneros wrote: > >> Not sure I see the problem you point here. In step 3, PQR_ASSOC is >> updated with RMID1, __pqr_update is the one called using the scheduler >> hook, right after perf sched_in . >> >> On Fri, Apr 29, 2016 at 1:25 PM, Vikas Shivappa >> wrote: >>> >>> >>> >>> On Thu, 28 Apr 2016, David Carrillo-Cisneros wrote: >>> >>>> Allow monitored cgroups to update the PQR MSR during task switch even >>>> without an associated perf_event. >>>> >>>> The package RMID for the current monr associated with a monitored >>>> cgroup is written to hw during task switch (after perf_events is run) >>>> if perf_event did not write a RMID for an event. >>>> >>>> perf_event and any other caller of pqr_cache_update_rmid can update the >>>> CPU's RMID using one of two modes: >>>> - PQR_RMID_MODE_NOEVENT: A RMID that do not correspond to an event. >>>> e.g. the RMID of the root pmonr when no event is scheduled. >>>> - PQR_RMID_MODE_EVENT: A RMID used by an event. Set during pmu::add >>>> unset on pmu::del. This mode prevents from using a non-event >>>> cgroup RMID. >>>> >>>> This patch also introduces caching of writes to PQR MSR within the >>>> per-pcu >>>> pqr state variable. This interface to update RMIDs and CLOSIDs will be >>>> also utilized in upcoming versions of Intel's MBM and CAT drivers. >>>> >>>> Reviewed-by: Stephane Eranian >>>> Signed-off-by: David Carrillo-Cisneros >>>> --- >>>> arch/x86/events/intel/cqm.c | 65 >>>> +++++++++++++++++++++++++++++---------- >>>> arch/x86/events/intel/cqm.h | 2 -- >>>> arch/x86/include/asm/pqr_common.h | 53 +++++++++++++++++++++++++++---- >>>> arch/x86/kernel/cpu/pqr_common.c | 46 +++++++++++++++++++++++---- >>>> 4 files changed, 135 insertions(+), 31 deletions(-) >>>> >>>> diff --git a/arch/x86/events/intel/cqm.c b/arch/x86/events/intel/cqm.c >>>> index daf9fdf..4ece0a4 100644 >>>> --- a/arch/x86/events/intel/cqm.c >>>> +++ b/arch/x86/events/intel/cqm.c >>>> @@ -198,19 +198,6 @@ static inline int cqm_prmid_update(struct prmid >>>> *prmid) >>>> return __cqm_prmid_update(prmid, __rmid_min_update_time); >>>> } >>>> >>>> -/* >>>> - * Updates caller cpu's cache. >>>> - */ >>>> -static inline void __update_pqr_prmid(struct prmid *prmid) >>>> -{ >>>> - struct intel_pqr_state *state = this_cpu_ptr(&pqr_state); >>>> - >>>> - if (state->rmid == prmid->rmid) >>>> - return; >>>> - state->rmid = prmid->rmid; >>>> - wrmsr(MSR_IA32_PQR_ASSOC, prmid->rmid, state->closid); >>>> -} >>>> - >>>> static inline bool __valid_pkg_id(u16 pkg_id) >>>> { >>>> return pkg_id < PQR_MAX_NR_PKGS; >>>> @@ -2531,12 +2518,11 @@ static inline bool cqm_group_leader(struct >>>> perf_event *event) >>>> static inline void __intel_cqm_event_start( >>>> struct perf_event *event, union prmid_summary summary) >>>> { >>>> - u16 pkg_id = topology_physical_package_id(smp_processor_id()); >>>> if (!(event->hw.state & PERF_HES_STOPPED)) >>>> return; >>>> - >>>> event->hw.state &= ~PERF_HES_STOPPED; >>>> - __update_pqr_prmid(__prmid_from_rmid(pkg_id, >>>> summary.sched_rmid)); >>>> + >>>> + pqr_cache_update_rmid(summary.sched_rmid, PQR_RMID_MODE_EVENT); >>>> } >>>> >>>> static void intel_cqm_event_start(struct perf_event *event, int mode) >>>> @@ -2566,7 +2552,7 @@ static void intel_cqm_event_stop(struct perf_event >>>> *event, int mode) >>>> /* Occupancy of CQM events is obtained at read. No need to read >>>> * when event is stopped since read on inactive cpus succeed. >>>> */ >>>> - __update_pqr_prmid(__prmid_from_rmid(pkg_id, >>>> summary.sched_rmid)); >>>> + pqr_cache_update_rmid(summary.sched_rmid, >>>> PQR_RMID_MODE_NOEVENT); >>>> } >>>> >>>> static int intel_cqm_event_add(struct perf_event *event, int mode) >>>> @@ -2977,6 +2963,8 @@ static void intel_cqm_cpu_starting(unsigned int >>>> cpu) >>>> >>>> state->rmid = 0; >>>> state->closid = 0; >>>> + state->next_rmid = 0; >>>> + state->next_closid = 0; >>>> >>>> /* XXX: lock */ >>>> /* XXX: Make sure this case is handled when hotplug happens. */ >>>> @@ -3152,6 +3140,12 @@ static int __init intel_cqm_init(void) >>>> pr_info("Intel CQM monitoring enabled with at least %u rmids per >>>> package.\n", >>>> min_max_rmid + 1); >>>> >>>> + /* Make sure pqr_common_enable_key is enabled after >>>> + * cqm_initialized_key. >>>> + */ >>>> + barrier(); >>>> + >>>> + static_branch_enable(&pqr_common_enable_key); >>>> return ret; >>>> >>>> error_init_mutex: >>>> @@ -3163,4 +3157,41 @@ error: >>>> return ret; >>>> } >>>> >>>> +/* Schedule task without a CQM perf_event. */ >>>> +inline void __intel_cqm_no_event_sched_in(void) >>>> +{ >>>> +#ifdef CONFIG_CGROUP_PERF >>>> + struct monr *monr; >>>> + struct pmonr *pmonr; >>>> + union prmid_summary summary; >>>> + u16 pkg_id = topology_physical_package_id(smp_processor_id()); >>>> + struct pmonr *root_pmonr = monr_hrchy_root->pmonrs[pkg_id]; >>>> + >>>> + /* Assume CQM enabled is likely given that PQR is enabled. */ >>>> + if (!static_branch_likely(&cqm_initialized_key)) >>>> + return; >>>> + >>>> + /* Safe to call from_task since we are in scheduler lock. */ >>>> + monr = monr_from_perf_cgroup(perf_cgroup_from_task(current, >>>> NULL)); >>>> + pmonr = monr->pmonrs[pkg_id]; >>>> + >>>> + /* Utilize most up to date pmonr summary. */ >>>> + monr_hrchy_get_next_prmid_summary(pmonr); >>>> + summary.value = atomic64_read(&pmonr->prmid_summary_atomic); >>>> + >>>> + if (!prmid_summary__is_mon_active(summary)) >>>> + goto no_rmid; >>>> + >>>> + if (WARN_ON_ONCE(!__valid_rmid(pkg_id, summary.sched_rmid))) >>>> + goto no_rmid; >>>> + >>>> + pqr_cache_update_rmid(summary.sched_rmid, >>>> PQR_RMID_MODE_NOEVENT); >>>> + return; >>>> + >>>> +no_rmid: >>>> + summary.value = >>>> atomic64_read(&root_pmonr->prmid_summary_atomic); >>>> + pqr_cache_update_rmid(summary.sched_rmid, >>>> PQR_RMID_MODE_NOEVENT); >>>> +#endif >>>> +} >>>> + >>>> device_initcall(intel_cqm_init); >>>> diff --git a/arch/x86/events/intel/cqm.h b/arch/x86/events/intel/cqm.h >>>> index 0f3da94..e1f8bd0 100644 >>>> --- a/arch/x86/events/intel/cqm.h >>>> +++ b/arch/x86/events/intel/cqm.h >>>> @@ -82,8 +82,6 @@ union prmid_summary { >>>> }; >>>> }; >>>> >>>> -# define INVALID_RMID (-1) >>>> - >>>> /* A pmonr in (U)state has no sched_rmid, read_rmid can be 0 or >>>> INVALID_RMID >>>> * depending on whether monitoring is active or not. >>>> */ >>>> diff --git a/arch/x86/include/asm/pqr_common.h >>>> b/arch/x86/include/asm/pqr_common.h >>>> index f770637..abbb235 100644 >>>> --- a/arch/x86/include/asm/pqr_common.h >>>> +++ b/arch/x86/include/asm/pqr_common.h >>>> @@ -3,31 +3,72 @@ >>>> >>>> #if defined(CONFIG_INTEL_RDT) >>>> >>>> +#include >>>> #include >>>> #include >>>> +#include >>>> >>>> #define MSR_IA32_PQR_ASSOC 0x0c8f >>>> +#define INVALID_RMID (-1) >>>> +#define INVALID_CLOSID (-1) >>>> + >>>> + >>>> +extern struct static_key_false pqr_common_enable_key; >>>> + >>>> +enum intel_pqr_rmid_mode { >>>> + /* RMID has no perf_event associated. */ >>>> + PQR_RMID_MODE_NOEVENT = 0, >>>> + /* RMID has a perf_event associated. */ >>>> + PQR_RMID_MODE_EVENT >>>> +}; >>>> >>>> /** >>>> * struct intel_pqr_state - State cache for the PQR MSR >>>> - * @rmid: The cached Resource Monitoring ID >>>> - * @closid: The cached Class Of Service ID >>>> + * @rmid: Last rmid written to hw. >>>> + * @next_rmid: Next rmid to write to hw. >>>> + * @next_rmid_mode: Next rmid's mode. >>>> + * @closid: The current Class Of Service ID >>>> + * @next_closid: The Class Of Service ID to use. >>>> * >>>> * The upper 32 bits of MSR_IA32_PQR_ASSOC contain closid and the >>>> * lower 10 bits rmid. The update to MSR_IA32_PQR_ASSOC always >>>> * contains both parts, so we need to cache them. >>>> * >>>> - * The cache also helps to avoid pointless updates if the value does >>>> - * not change. >>>> + * The cache also helps to avoid pointless updates if the value does >>>> not >>>> + * change. It also keeps track of the type of RMID set (event vs no >>>> event) >>>> + * used to determine when a cgroup RMID is required. >>>> */ >>>> struct intel_pqr_state { >>>> - u32 rmid; >>>> - u32 closid; >>>> + u32 rmid; >>>> + u32 next_rmid; >>>> + enum intel_pqr_rmid_mode next_rmid_mode; >>>> + u32 closid; >>>> + u32 next_closid; >>>> }; >>>> >>>> DECLARE_PER_CPU(struct intel_pqr_state, pqr_state); >>>> >>>> #define PQR_MAX_NR_PKGS 8 >>>> >>>> +void __pqr_update(void); >>>> + >>>> +inline void __intel_cqm_no_event_sched_in(void); >>>> + >>>> +inline void pqr_cache_update_rmid(u32 rmid, enum intel_pqr_rmid_mode >>>> mode); >>>> + >>>> +inline void pqr_cache_update_closid(u32 closid); >>>> + >>>> +static inline void pqr_update(void) >>>> +{ >>>> + if (static_branch_unlikely(&pqr_common_enable_key)) >>>> + __pqr_update(); >>>> +} >>>> + >>>> +#else >>>> + >>>> +static inline void pqr_update(void) >>>> +{ >>>> +} >>>> + >>>> #endif >>>> #endif >>>> diff --git a/arch/x86/kernel/cpu/pqr_common.c >>>> b/arch/x86/kernel/cpu/pqr_common.c >>>> index 9eff5d9..d91c127 100644 >>>> --- a/arch/x86/kernel/cpu/pqr_common.c >>>> +++ b/arch/x86/kernel/cpu/pqr_common.c >>>> @@ -1,9 +1,43 @@ >>>> #include >>>> >>>> -/* >>>> - * The cached intel_pqr_state is strictly per CPU and can never be >>>> - * updated from a remote CPU. Both functions which modify the state >>>> - * (intel_cqm_event_start and intel_cqm_event_stop) are called with >>>> - * interrupts disabled, which is sufficient for the protection. >>>> - */ >>>> DEFINE_PER_CPU(struct intel_pqr_state, pqr_state); >>>> + >>>> +DEFINE_STATIC_KEY_FALSE(pqr_common_enable_key); >>>> + >>>> +inline void pqr_cache_update_rmid(u32 rmid, enum intel_pqr_rmid_mode >>>> mode) >>>> +{ >>>> + struct intel_pqr_state *state = this_cpu_ptr(&pqr_state); >>>> + >>>> + state->next_rmid_mode = mode; >>>> + state->next_rmid = rmid; >>>> +} >>>> + >>>> +inline void pqr_cache_update_closid(u32 closid) >>>> +{ >>>> + struct intel_pqr_state *state = this_cpu_ptr(&pqr_state); >>>> + >>>> + state->next_closid = closid; >>>> +} >>>> + >>>> +/* Update hw's RMID using cgroup's if perf_event did not. >>>> + * Sync pqr cache with MSR. >>>> + */ >>>> +inline void __pqr_update(void) >>>> +{ >>>> + struct intel_pqr_state *state = this_cpu_ptr(&pqr_state); >>>> + >>>> + /* If perf_event has set a next_rmid that is used, do not try >>>> + * to obtain another one from current task. >>>> + */ >>>> + if (state->next_rmid_mode == PQR_RMID_MODE_NOEVENT) >>>> + __intel_cqm_no_event_sched_in(); >>> >>> >>> >>> if perf_cgroup is not defined then the state is not updated here so the >>> state might have state->rmid might have IDs ? >>> >>> 1.event1 for PID1 has RMID1, >>> 2.perf sched_in - state->next_rmid = rmid1 >>> 3.pqr_update - state->rmid = rmid1 >>> 4.sched_out - write PQR_NOEVENT - >>> 5.next switch_to - state->rmid not reset nothing changes (when no >>> perf_cgroup) ? > > > Between 4 and 5 say event1 is dead. Basically on the next context switch(#5) > if perf sched_in wasnt called the PQR still has RMID1. > > When you have perf_cgroup you call the __intel_cqm_no_event.. then it sees > if there is continuous monitoring or you set the next_rmid to 0- but all the > code there is inside #ifdef PERF_CGROUP, so without cgroup its never reset > to zero ? > > > >>> >>> >>>> + >>>> + /* __intel_cqm_no_event_sched_in might have changed next_rmid. >>>> */ >>>> + if (state->rmid == state->next_rmid && >>>> + state->closid == state->next_closid) >>>> + return; >>>> + >>>> + state->rmid = state->next_rmid; >>>> + state->closid = state->next_closid; >>>> + wrmsr(MSR_IA32_PQR_ASSOC, state->rmid, state->closid); >>>> +} >>>> -- >>>> 2.8.0.rc3.226.g39d4020 >>>> >>>> >>> >> >