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Message-ID: <CALPaoCj8yfzJ=5CkxTPQXc0-WRWpu0xKRX8v4FAWFGQKtXtMUw@mail.gmail.com>
Date: Fri, 23 May 2025 11:00:04 +0200
From: Peter Newman <peternewman@...gle.com>
To: Tony Luck <tony.luck@...el.com>
Cc: Fenghua Yu <fenghuay@...dia.com>, Reinette Chatre <reinette.chatre@...el.com>,
Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>, James Morse <james.morse@....com>,
Babu Moger <babu.moger@....com>, Drew Fustini <dfustini@...libre.com>,
Dave Martin <Dave.Martin@....com>, Anil Keshavamurthy <anil.s.keshavamurthy@...el.com>,
Chen Yu <yu.c.chen@...el.com>, x86@...nel.org, linux-kernel@...r.kernel.org,
patches@...ts.linux.dev
Subject: Re: [PATCH v5 04/29] x86,fs/resctrl: Prepare for more monitor events
Hi Tony,
On Thu, May 22, 2025 at 12:51 AM Tony Luck <tony.luck@...el.com> wrote:
>
> There's a rule in computer programming that objects appear zero,
> once, or many times. So code accordingly.
>
> There are two MBM events and resctrl is coded with a lot of
>
> if (local)
> do one thing
> if (total)
> do a different thing
>
> Change the rdt_mon_domain and rdt_hw_mon_domain structures to hold arrays
> of pointers to per event data instead of explicit fields for total and
> local bandwidth.
>
> Simplify by coding for many events using loops on which are enabled.
>
> Move resctrl_is_mbm_event() to <linux/resctrl.h> so it can be used more
> widely. Also provide a for_each_mbm_event() helper macro.
>
> Signed-off-by: Tony Luck <tony.luck@...el.com>
> ---
> include/linux/resctrl.h | 15 +++++---
> include/linux/resctrl_types.h | 3 ++
> arch/x86/kernel/cpu/resctrl/internal.h | 6 ++--
> arch/x86/kernel/cpu/resctrl/core.c | 38 ++++++++++----------
> arch/x86/kernel/cpu/resctrl/monitor.c | 36 +++++++++----------
> fs/resctrl/monitor.c | 13 ++++---
> fs/resctrl/rdtgroup.c | 48 ++++++++++++--------------
> 7 files changed, 82 insertions(+), 77 deletions(-)
>
> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
> index 843ad7c8e247..40f2d0d48d02 100644
> --- a/include/linux/resctrl.h
> +++ b/include/linux/resctrl.h
> @@ -161,8 +161,7 @@ struct rdt_ctrl_domain {
> * @hdr: common header for different domain types
> * @ci: cache info for this domain
> * @rmid_busy_llc: bitmap of which limbo RMIDs are above threshold
> - * @mbm_total: saved state for MBM total bandwidth
> - * @mbm_local: saved state for MBM local bandwidth
> + * @mbm_states: saved state for each QOS MBM event
> * @mbm_over: worker to periodically read MBM h/w counters
> * @cqm_limbo: worker to periodically read CQM h/w counters
> * @mbm_work_cpu: worker CPU for MBM h/w counters
> @@ -172,8 +171,7 @@ struct rdt_mon_domain {
> struct rdt_domain_hdr hdr;
> struct cacheinfo *ci;
> unsigned long *rmid_busy_llc;
> - struct mbm_state *mbm_total;
> - struct mbm_state *mbm_local;
> + struct mbm_state *mbm_states[QOS_NUM_L3_MBM_EVENTS];
> struct delayed_work mbm_over;
> struct delayed_work cqm_limbo;
> int mbm_work_cpu;
> @@ -376,6 +374,15 @@ bool resctrl_is_mon_event_enabled(enum resctrl_event_id evt);
>
> bool resctrl_arch_is_evt_configurable(enum resctrl_event_id evt);
>
> +static inline bool resctrl_is_mbm_event(enum resctrl_event_id e)
> +{
> + return (e >= QOS_L3_MBM_TOTAL_EVENT_ID &&
> + e <= QOS_L3_MBM_LOCAL_EVENT_ID);
> +}
> +
> +#define for_each_mbm_event(evt) \
> + for (evt = QOS_L3_MBM_TOTAL_EVENT_ID; evt <= QOS_L3_MBM_LOCAL_EVENT_ID; evt++)
> +
> /**
> * resctrl_arch_mon_event_config_write() - Write the config for an event.
> * @config_info: struct resctrl_mon_config_info describing the resource, domain
> diff --git a/include/linux/resctrl_types.h b/include/linux/resctrl_types.h
> index a25fb9c4070d..b468bfbab9ea 100644
> --- a/include/linux/resctrl_types.h
> +++ b/include/linux/resctrl_types.h
> @@ -47,4 +47,7 @@ enum resctrl_event_id {
> QOS_NUM_EVENTS,
> };
>
> +#define QOS_NUM_L3_MBM_EVENTS (QOS_L3_MBM_LOCAL_EVENT_ID - QOS_L3_MBM_TOTAL_EVENT_ID + 1)
> +#define MBM_STATE_IDX(evt) ((evt) - QOS_L3_MBM_TOTAL_EVENT_ID)
> +
> #endif /* __LINUX_RESCTRL_TYPES_H */
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index 5e3c41b36437..ea185b4d0d59 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -54,15 +54,13 @@ struct rdt_hw_ctrl_domain {
> * struct rdt_hw_mon_domain - Arch private attributes of a set of CPUs that share
> * a resource for a monitor function
> * @d_resctrl: Properties exposed to the resctrl file system
> - * @arch_mbm_total: arch private state for MBM total bandwidth
> - * @arch_mbm_local: arch private state for MBM local bandwidth
> + * @arch_mbm_states: arch private state for each MBM event
> *
> * Members of this structure are accessed via helpers that provide abstraction.
> */
> struct rdt_hw_mon_domain {
> struct rdt_mon_domain d_resctrl;
> - struct arch_mbm_state *arch_mbm_total;
> - struct arch_mbm_state *arch_mbm_local;
> + struct arch_mbm_state *arch_mbm_states[QOS_NUM_L3_MBM_EVENTS];
> };
>
> static inline struct rdt_hw_ctrl_domain *resctrl_to_arch_ctrl_dom(struct rdt_ctrl_domain *r)
> diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
> index 819bc7a09327..4403a820db12 100644
> --- a/arch/x86/kernel/cpu/resctrl/core.c
> +++ b/arch/x86/kernel/cpu/resctrl/core.c
> @@ -364,8 +364,8 @@ static void ctrl_domain_free(struct rdt_hw_ctrl_domain *hw_dom)
>
> static void mon_domain_free(struct rdt_hw_mon_domain *hw_dom)
> {
> - kfree(hw_dom->arch_mbm_total);
> - kfree(hw_dom->arch_mbm_local);
> + for (int i = 0; i < QOS_NUM_L3_MBM_EVENTS; i++)
> + kfree(hw_dom->arch_mbm_states[i]);
> kfree(hw_dom);
> }
>
> @@ -399,25 +399,27 @@ static int domain_setup_ctrlval(struct rdt_resource *r, struct rdt_ctrl_domain *
> */
> static int arch_domain_mbm_alloc(u32 num_rmid, struct rdt_hw_mon_domain *hw_dom)
> {
> - size_t tsize;
> -
> - if (resctrl_is_mon_event_enabled(QOS_L3_MBM_TOTAL_EVENT_ID)) {
> - tsize = sizeof(*hw_dom->arch_mbm_total);
> - hw_dom->arch_mbm_total = kcalloc(num_rmid, tsize, GFP_KERNEL);
> - if (!hw_dom->arch_mbm_total)
> - return -ENOMEM;
> - }
> - if (resctrl_is_mon_event_enabled(QOS_L3_MBM_LOCAL_EVENT_ID)) {
> - tsize = sizeof(*hw_dom->arch_mbm_local);
> - hw_dom->arch_mbm_local = kcalloc(num_rmid, tsize, GFP_KERNEL);
> - if (!hw_dom->arch_mbm_local) {
> - kfree(hw_dom->arch_mbm_total);
> - hw_dom->arch_mbm_total = NULL;
> - return -ENOMEM;
> - }
> + size_t tsize = sizeof(struct arch_mbm_state);
sizeof(*hw_dom->arch_mbm_states[0])?
The previous code didn't assume a type.
> + enum resctrl_event_id evt;
> + int idx;
> +
> + for_each_mbm_event(evt) {
> + if (!resctrl_is_mon_event_enabled(evt))
> + continue;
> + idx = MBM_STATE_IDX(evt);
> + hw_dom->arch_mbm_states[idx] = kcalloc(num_rmid, tsize, GFP_KERNEL);
> + if (!hw_dom->arch_mbm_states[idx])
> + goto cleanup;
> }
>
> return 0;
> +cleanup:
> + while (--idx >= 0) {
> + kfree(hw_dom->arch_mbm_states[idx]);
> + hw_dom->arch_mbm_states[idx] = NULL;
> + }
> +
> + return -ENOMEM;
> }
>
> static int get_domain_id_from_scope(int cpu, enum resctrl_scope scope)
> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
> index fda579251dba..85526e5540f2 100644
> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
> @@ -160,18 +160,14 @@ static struct arch_mbm_state *get_arch_mbm_state(struct rdt_hw_mon_domain *hw_do
> u32 rmid,
> enum resctrl_event_id eventid)
> {
> - switch (eventid) {
> - case QOS_L3_OCCUP_EVENT_ID:
> - return NULL;
> - case QOS_L3_MBM_TOTAL_EVENT_ID:
> - return &hw_dom->arch_mbm_total[rmid];
> - case QOS_L3_MBM_LOCAL_EVENT_ID:
> - return &hw_dom->arch_mbm_local[rmid];
> - default:
> - /* Never expect to get here */
> - WARN_ON_ONCE(1);
> + struct arch_mbm_state *state;
> +
> + if (!resctrl_is_mbm_event(eventid))
> return NULL;
> - }
> +
> + state = hw_dom->arch_mbm_states[MBM_STATE_IDX(eventid)];
> +
> + return state ? &state[rmid] : NULL;
> }
>
> void resctrl_arch_reset_rmid(struct rdt_resource *r, struct rdt_mon_domain *d,
> @@ -200,14 +196,16 @@ void resctrl_arch_reset_rmid(struct rdt_resource *r, struct rdt_mon_domain *d,
> void resctrl_arch_reset_rmid_all(struct rdt_resource *r, struct rdt_mon_domain *d)
> {
> struct rdt_hw_mon_domain *hw_dom = resctrl_to_arch_mon_dom(d);
> -
> - if (resctrl_is_mon_event_enabled(QOS_L3_MBM_TOTAL_EVENT_ID))
> - memset(hw_dom->arch_mbm_total, 0,
> - sizeof(*hw_dom->arch_mbm_total) * r->num_rmid);
> -
> - if (resctrl_is_mon_event_enabled(QOS_L3_MBM_LOCAL_EVENT_ID))
> - memset(hw_dom->arch_mbm_local, 0,
> - sizeof(*hw_dom->arch_mbm_local) * r->num_rmid);
> + enum resctrl_event_id evt;
> + int idx;
> +
> + for_each_mbm_event(evt) {
> + idx = MBM_STATE_IDX(evt);
> + if (!hw_dom->arch_mbm_states[idx])
> + continue;
> + memset(hw_dom->arch_mbm_states[idx], 0,
> + sizeof(struct arch_mbm_state) * r->num_rmid);
> + }
> }
>
> static u64 mbm_overflow_count(u64 prev_msr, u64 cur_msr, unsigned int width)
> diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
> index 325e23c1a403..4cd0789998bf 100644
> --- a/fs/resctrl/monitor.c
> +++ b/fs/resctrl/monitor.c
> @@ -346,15 +346,14 @@ static struct mbm_state *get_mbm_state(struct rdt_mon_domain *d, u32 closid,
> u32 rmid, enum resctrl_event_id evtid)
> {
> u32 idx = resctrl_arch_rmid_idx_encode(closid, rmid);
> + struct mbm_state *states;
>
> - switch (evtid) {
> - case QOS_L3_MBM_TOTAL_EVENT_ID:
> - return &d->mbm_total[idx];
> - case QOS_L3_MBM_LOCAL_EVENT_ID:
> - return &d->mbm_local[idx];
> - default:
> + if (!resctrl_is_mbm_event(evtid))
> return NULL;
> - }
> +
> + states = d->mbm_states[MBM_STATE_IDX(evtid)];
> +
> + return states ? &states[idx] : NULL;
> }
>
> static int __mon_event_count(u32 closid, u32 rmid, struct rmid_read *rr)
> diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
> index 80e74940281a..8649b89d7bfd 100644
> --- a/fs/resctrl/rdtgroup.c
> +++ b/fs/resctrl/rdtgroup.c
> @@ -127,12 +127,6 @@ static bool resctrl_is_mbm_enabled(void)
> resctrl_is_mon_event_enabled(QOS_L3_MBM_LOCAL_EVENT_ID));
> }
>
> -static bool resctrl_is_mbm_event(int e)
> -{
> - return (e >= QOS_L3_MBM_TOTAL_EVENT_ID &&
> - e <= QOS_L3_MBM_LOCAL_EVENT_ID);
> -}
> -
> /*
> * Trivial allocator for CLOSIDs. Use BITMAP APIs to manipulate a bitmap
> * of free CLOSIDs.
> @@ -4020,8 +4014,10 @@ static void rdtgroup_setup_default(void)
> static void domain_destroy_mon_state(struct rdt_mon_domain *d)
> {
> bitmap_free(d->rmid_busy_llc);
> - kfree(d->mbm_total);
> - kfree(d->mbm_local);
> + for (int i = 0; i < QOS_NUM_L3_MBM_EVENTS; i++) {
> + kfree(d->mbm_states[i]);
> + d->mbm_states[i] = NULL;
> + }
> }
>
> void resctrl_offline_ctrl_domain(struct rdt_resource *r, struct rdt_ctrl_domain *d)
> @@ -4081,32 +4077,34 @@ void resctrl_offline_mon_domain(struct rdt_resource *r, struct rdt_mon_domain *d
> static int domain_setup_mon_state(struct rdt_resource *r, struct rdt_mon_domain *d)
> {
> u32 idx_limit = resctrl_arch_system_num_rmid_idx();
> - size_t tsize;
> + size_t tsize = sizeof(struct mbm_state);
Here too.
Thanks!
-Peter
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