diff options
| -rw-r--r-- | Documentation/x86/resctrl_ui.rst | 18 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/resctrl/core.c | 11 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/resctrl/internal.h | 30 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/resctrl/rdtgroup.c | 53 |
4 files changed, 103 insertions, 9 deletions
diff --git a/Documentation/x86/resctrl_ui.rst b/Documentation/x86/resctrl_ui.rst index 5368cedfb530..e59b7b93a9b4 100644 --- a/Documentation/x86/resctrl_ui.rst +++ b/Documentation/x86/resctrl_ui.rst @@ -138,6 +138,18 @@ with respect to allocation: non-linear. This field is purely informational only. +"thread_throttle_mode": + Indicator on Intel systems of how tasks running on threads + of a physical core are throttled in cases where they + request different memory bandwidth percentages: + + "max": + the smallest percentage is applied + to all threads + "per-thread": + bandwidth percentages are directly applied to + the threads running on the core + If RDT monitoring is available there will be an "L3_MON" directory with the following files: @@ -364,8 +376,10 @@ to the next control step available on the hardware. The bandwidth throttling is a core specific mechanism on some of Intel SKUs. Using a high bandwidth and a low bandwidth setting on two threads -sharing a core will result in both threads being throttled to use the -low bandwidth. The fact that Memory bandwidth allocation(MBA) is a core +sharing a core may result in both threads being throttled to use the +low bandwidth (see "thread_throttle_mode"). + +The fact that Memory bandwidth allocation(MBA) may be a core specific mechanism where as memory bandwidth monitoring(MBM) is done at the package level may lead to confusion when users try to apply control via the MBA and then monitor the bandwidth to see if the controls are diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c index 1c00f2f0bf0c..9e1712e8aef7 100644 --- a/arch/x86/kernel/cpu/resctrl/core.c +++ b/arch/x86/kernel/cpu/resctrl/core.c @@ -273,6 +273,12 @@ static bool __get_mem_config_intel(struct rdt_resource *r) } r->data_width = 3; + if (boot_cpu_has(X86_FEATURE_PER_THREAD_MBA)) + r->membw.throttle_mode = THREAD_THROTTLE_PER_THREAD; + else + r->membw.throttle_mode = THREAD_THROTTLE_MAX; + thread_throttle_mode_init(); + r->alloc_capable = true; r->alloc_enabled = true; @@ -293,6 +299,11 @@ static bool __rdt_get_mem_config_amd(struct rdt_resource *r) r->membw.delay_linear = false; r->membw.arch_needs_linear = false; + /* + * AMD does not use memory delay throttle model to control + * the allocation like Intel does. + */ + r->membw.throttle_mode = THREAD_THROTTLE_UNDEFINED; r->membw.min_bw = 0; r->membw.bw_gran = 1; /* Max value is 2048, Data width should be 4 in decimal */ diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h index 0b4829484c9e..80fa997fae60 100644 --- a/arch/x86/kernel/cpu/resctrl/internal.h +++ b/arch/x86/kernel/cpu/resctrl/internal.h @@ -372,21 +372,38 @@ struct rdt_cache { }; /** + * enum membw_throttle_mode - System's memory bandwidth throttling mode + * @THREAD_THROTTLE_UNDEFINED: Not relevant to the system + * @THREAD_THROTTLE_MAX: Memory bandwidth is throttled at the core + * always using smallest bandwidth percentage + * assigned to threads, aka "max throttling" + * @THREAD_THROTTLE_PER_THREAD: Memory bandwidth is throttled at the thread + */ +enum membw_throttle_mode { + THREAD_THROTTLE_UNDEFINED = 0, + THREAD_THROTTLE_MAX, + THREAD_THROTTLE_PER_THREAD, +}; + +/** * struct rdt_membw - Memory bandwidth allocation related data * @min_bw: Minimum memory bandwidth percentage user can request * @bw_gran: Granularity at which the memory bandwidth is allocated * @delay_linear: True if memory B/W delay is in linear scale * @arch_needs_linear: True if we can't configure non-linear resources + * @throttle_mode: Bandwidth throttling mode when threads request + * different memory bandwidths * @mba_sc: True if MBA software controller(mba_sc) is enabled * @mb_map: Mapping of memory B/W percentage to memory B/W delay */ struct rdt_membw { - u32 min_bw; - u32 bw_gran; - u32 delay_linear; - bool arch_needs_linear; - bool mba_sc; - u32 *mb_map; + u32 min_bw; + u32 bw_gran; + u32 delay_linear; + bool arch_needs_linear; + enum membw_throttle_mode throttle_mode; + bool mba_sc; + u32 *mb_map; }; static inline bool is_llc_occupancy_enabled(void) @@ -607,5 +624,6 @@ void cqm_handle_limbo(struct work_struct *work); bool has_busy_rmid(struct rdt_resource *r, struct rdt_domain *d); void __check_limbo(struct rdt_domain *d, bool force_free); void rdt_domain_reconfigure_cdp(struct rdt_resource *r); +void __init thread_throttle_mode_init(void); #endif /* _ASM_X86_RESCTRL_INTERNAL_H */ diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c index 78f3be10e215..b494187632b2 100644 --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c @@ -1027,6 +1027,19 @@ static int max_threshold_occ_show(struct kernfs_open_file *of, return 0; } +static int rdt_thread_throttle_mode_show(struct kernfs_open_file *of, + struct seq_file *seq, void *v) +{ + struct rdt_resource *r = of->kn->parent->priv; + + if (r->membw.throttle_mode == THREAD_THROTTLE_PER_THREAD) + seq_puts(seq, "per-thread\n"); + else + seq_puts(seq, "max\n"); + + return 0; +} + static ssize_t max_threshold_occ_write(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off) { @@ -1523,6 +1536,17 @@ static struct rftype res_common_files[] = { .seq_show = rdt_delay_linear_show, .fflags = RF_CTRL_INFO | RFTYPE_RES_MB, }, + /* + * Platform specific which (if any) capabilities are provided by + * thread_throttle_mode. Defer "fflags" initialization to platform + * discovery. + */ + { + .name = "thread_throttle_mode", + .mode = 0444, + .kf_ops = &rdtgroup_kf_single_ops, + .seq_show = rdt_thread_throttle_mode_show, + }, { .name = "max_threshold_occupancy", .mode = 0644, @@ -1593,7 +1617,7 @@ static int rdtgroup_add_files(struct kernfs_node *kn, unsigned long fflags) lockdep_assert_held(&rdtgroup_mutex); for (rft = rfts; rft < rfts + len; rft++) { - if ((fflags & rft->fflags) == rft->fflags) { + if (rft->fflags && ((fflags & rft->fflags) == rft->fflags)) { ret = rdtgroup_add_file(kn, rft); if (ret) goto error; @@ -1610,6 +1634,33 @@ error: return ret; } +static struct rftype *rdtgroup_get_rftype_by_name(const char *name) +{ + struct rftype *rfts, *rft; + int len; + + rfts = res_common_files; + len = ARRAY_SIZE(res_common_files); + + for (rft = rfts; rft < rfts + len; rft++) { + if (!strcmp(rft->name, name)) + return rft; + } + + return NULL; +} + +void __init thread_throttle_mode_init(void) +{ + struct rftype *rft; + + rft = rdtgroup_get_rftype_by_name("thread_throttle_mode"); + if (!rft) + return; + + rft->fflags = RF_CTRL_INFO | RFTYPE_RES_MB; +} + /** * rdtgroup_kn_mode_restrict - Restrict user access to named resctrl file * @r: The resource group with which the file is associated. |