Re: [PATCH v5 5/5] sched: rename SD_SHARE_PKG_RESOURCES to SD_SHARE_LLC

From: Barry Song
Date: Tue Feb 13 2024 - 02:21:44 EST

On Tue, Feb 13, 2024 at 8:01 PM Barry Song <21cnbao@xxxxxxxxx> wrote:
>
> Hi Alex, Valentin,
>
>
> On Sun, Feb 11, 2024 at 12:37 AM <alexs@xxxxxxxxxx> wrote:
> >
> > From: Alex Shi <alexs@xxxxxxxxxx>
> >
> > SD_CLUSTER shares the CPU resources like llc tags or l2 cache, that's
> > easy confuse with SD_SHARE_PKG_RESOURCES. So let's specifical point
> > what the latter shares: LLC. That would reduce some confusing.
>
> On neither JACOBSVILLE nor kunpeng920, it seems CLUSTER isn't LLC.
> on Jacobsville, cluster is L2-cache while Jacobsville has L3; on kunpeng920,
> cluster is L3-tag. On kunpeng920, actually 24 cpus or 32cpus share one LLC,
> the whole L3. cluster is kind of like middle-level caches.
>
> So I feel this patch isn't precise.

sorry for my noise, i thought you were renaming cluster to LLC. but after
second reading, you are renaming the level after cluster, so my comment
was wrong. Please feel free to add:

Reviewed-by: Barry Song <baohua@xxxxxxxxxx>

>
> >
> > Suggested-by: Valentin Schneider <vschneid@xxxxxxxxxx>
> > Signed-off-by: Alex Shi <alexs@xxxxxxxxxx>
> > Cc: linux-kernel@xxxxxxxxxxxxxxx
> > Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
> > Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
> > Cc: Barry Song <song.bao.hua@xxxxxxxxxxxxx>
> > Cc: Mark Rutland <mark.rutland@xxxxxxx>
> > Cc: Frederic Weisbecker <frederic@xxxxxxxxxx>
> > Cc: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
> > Cc: Ben Segall <bsegall@xxxxxxxxxx>
> > Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> > Cc: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
> > Cc: Juri Lelli <juri.lelli@xxxxxxxxxx>
> > Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> > Cc: "Naveen N. Rao" <naveen.n.rao@xxxxxxxxxxxxx>
> > Cc: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxx>
> > Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
> > Cc: "Gautham R. Shenoy" <gautham.shenoy@xxxxxxx>
> > Cc: Yicong Yang <yangyicong@xxxxxxxxxxxxx>
> > Cc: Ricardo Neri <ricardo.neri-calderon@xxxxxxxxxxxxxxx>
> > Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> > Cc: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
> > Cc: Valentin Schneider <vschneid@xxxxxxxxxx>
> > Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
> > Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> > Reviewed-by: Valentin Schneider <vschneid@xxxxxxxxxx>
> > Reviewed-by: Ricardo Neri <ricardo.neri-calderon@xxxxxxxxxxxxxxx>
> > ---
> > arch/powerpc/kernel/smp.c | 6 +++---
> > include/linux/sched/sd_flags.h | 4 ++--
> > include/linux/sched/topology.h | 6 +++---
> > kernel/sched/fair.c | 2 +-
> > kernel/sched/topology.c | 28 ++++++++++++++--------------
> > 5 files changed, 23 insertions(+), 23 deletions(-)
> >
> > diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
> > index 693334c20d07..a60e4139214b 100644
> > --- a/arch/powerpc/kernel/smp.c
> > +++ b/arch/powerpc/kernel/smp.c
> > @@ -984,7 +984,7 @@ static bool shared_caches __ro_after_init;
> > /* cpumask of CPUs with asymmetric SMT dependency */
> > static int powerpc_smt_flags(void)
> > {
> > - int flags = SD_SHARE_CPUCAPACITY | SD_SHARE_PKG_RESOURCES;
> > + int flags = SD_SHARE_CPUCAPACITY | SD_SHARE_LLC;
> >
> > if (cpu_has_feature(CPU_FTR_ASYM_SMT)) {
> > printk_once(KERN_INFO "Enabling Asymmetric SMT scheduling\n");
> > @@ -1010,9 +1010,9 @@ static __ro_after_init DEFINE_STATIC_KEY_FALSE(splpar_asym_pack);
> > static int powerpc_shared_cache_flags(void)
> > {
> > if (static_branch_unlikely(&splpar_asym_pack))
> > - return SD_SHARE_PKG_RESOURCES | SD_ASYM_PACKING;
> > + return SD_SHARE_LLC | SD_ASYM_PACKING;
> >
> > - return SD_SHARE_PKG_RESOURCES;
> > + return SD_SHARE_LLC;
> > }
> >
> > static int powerpc_shared_proc_flags(void)
> > diff --git a/include/linux/sched/sd_flags.h b/include/linux/sched/sd_flags.h
> > index a8b28647aafc..b04a5d04dee9 100644
> > --- a/include/linux/sched/sd_flags.h
> > +++ b/include/linux/sched/sd_flags.h
> > @@ -117,13 +117,13 @@ SD_FLAG(SD_SHARE_CPUCAPACITY, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
> > SD_FLAG(SD_CLUSTER, SDF_NEEDS_GROUPS)
> >
> > /*
> > - * Domain members share CPU package resources (i.e. caches)
> > + * Domain members share CPU Last Level Caches
> > *
> > * SHARED_CHILD: Set from the base domain up until spanned CPUs no longer share
> > * the same cache(s).
> > * NEEDS_GROUPS: Caches are shared between groups.
> > */
> > -SD_FLAG(SD_SHARE_PKG_RESOURCES, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
> > +SD_FLAG(SD_SHARE_LLC, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
> >
> > /*
> > * Only a single load balancing instance
> > diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h
> > index a6e04b4a21d7..191b122158fb 100644
> > --- a/include/linux/sched/topology.h
> > +++ b/include/linux/sched/topology.h
> > @@ -38,21 +38,21 @@ extern const struct sd_flag_debug sd_flag_debug[];
> > #ifdef CONFIG_SCHED_SMT
> > static inline int cpu_smt_flags(void)
> > {
> > - return SD_SHARE_CPUCAPACITY | SD_SHARE_PKG_RESOURCES;
> > + return SD_SHARE_CPUCAPACITY | SD_SHARE_LLC;
> > }
> > #endif
> >
> > #ifdef CONFIG_SCHED_CLUSTER
> > static inline int cpu_cluster_flags(void)
> > {
> > - return SD_CLUSTER | SD_SHARE_PKG_RESOURCES;
> > + return SD_CLUSTER | SD_SHARE_LLC;
> > }
> > #endif
> >
> > #ifdef CONFIG_SCHED_MC
> > static inline int cpu_core_flags(void)
> > {
> > - return SD_SHARE_PKG_RESOURCES;
> > + return SD_SHARE_LLC;
> > }
> > #endif
> >
> > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> > index cd1ec57c0b7b..da6c77d05d07 100644
> > --- a/kernel/sched/fair.c
> > +++ b/kernel/sched/fair.c
> > @@ -10687,7 +10687,7 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s
> > */
> > if (local->group_type == group_has_spare) {
> > if ((busiest->group_type > group_fully_busy) &&
> > - !(env->sd->flags & SD_SHARE_PKG_RESOURCES)) {
> > + !(env->sd->flags & SD_SHARE_LLC)) {
> > /*
> > * If busiest is overloaded, try to fill spare
> > * capacity. This might end up creating spare capacity
> > diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
> > index 0b33f7b05d21..99ea5986038c 100644
> > --- a/kernel/sched/topology.c
> > +++ b/kernel/sched/topology.c
> > @@ -657,13 +657,13 @@ static void destroy_sched_domains(struct sched_domain *sd)
> > }
> >
> > /*
> > - * Keep a special pointer to the highest sched_domain that has
> > - * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
> > - * allows us to avoid some pointer chasing select_idle_sibling().
> > + * Keep a special pointer to the highest sched_domain that has SD_SHARE_LLC set
> > + * (Last Level Cache Domain) for this allows us to avoid some pointer chasing
> > + * select_idle_sibling().
> > *
> > - * Also keep a unique ID per domain (we use the first CPU number in
> > - * the cpumask of the domain), this allows us to quickly tell if
> > - * two CPUs are in the same cache domain, see cpus_share_cache().
> > + * Also keep a unique ID per domain (we use the first CPU number in the cpumask
> > + * of the domain), this allows us to quickly tell if two CPUs are in the same
> > + * cache domain, see cpus_share_cache().
> > */
> > DEFINE_PER_CPU(struct sched_domain __rcu *, sd_llc);
> > DEFINE_PER_CPU(int, sd_llc_size);
> > @@ -684,7 +684,7 @@ static void update_top_cache_domain(int cpu)
> > int id = cpu;
> > int size = 1;
> >
> > - sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
> > + sd = highest_flag_domain(cpu, SD_SHARE_LLC);
> > if (sd) {
> > id = cpumask_first(sched_domain_span(sd));
> > size = cpumask_weight(sched_domain_span(sd));
> > @@ -1554,7 +1554,7 @@ static struct cpumask ***sched_domains_numa_masks;
> > * function. For details, see include/linux/sched/sd_flags.h.
> > *
> > * SD_SHARE_CPUCAPACITY
> > - * SD_SHARE_PKG_RESOURCES
> > + * SD_SHARE_LLC
> > * SD_CLUSTER
> > * SD_NUMA
> > *
> > @@ -1566,7 +1566,7 @@ static struct cpumask ***sched_domains_numa_masks;
> > #define TOPOLOGY_SD_FLAGS \
> > (SD_SHARE_CPUCAPACITY | \
> > SD_CLUSTER | \
> > - SD_SHARE_PKG_RESOURCES | \
> > + SD_SHARE_LLC | \
> > SD_NUMA | \
> > SD_ASYM_PACKING)
> >
> > @@ -1609,7 +1609,7 @@ sd_init(struct sched_domain_topology_level *tl,
> > | 0*SD_BALANCE_WAKE
> > | 1*SD_WAKE_AFFINE
> > | 0*SD_SHARE_CPUCAPACITY
> > - | 0*SD_SHARE_PKG_RESOURCES
> > + | 0*SD_SHARE_LLC
> > | 0*SD_SERIALIZE
> > | 1*SD_PREFER_SIBLING
> > | 0*SD_NUMA
> > @@ -1646,7 +1646,7 @@ sd_init(struct sched_domain_topology_level *tl,
> > if (sd->flags & SD_SHARE_CPUCAPACITY) {
> > sd->imbalance_pct = 110;
> >
> > - } else if (sd->flags & SD_SHARE_PKG_RESOURCES) {
> > + } else if (sd->flags & SD_SHARE_LLC) {
> > sd->imbalance_pct = 117;
> > sd->cache_nice_tries = 1;
> >
> > @@ -1671,7 +1671,7 @@ sd_init(struct sched_domain_topology_level *tl,
> > * For all levels sharing cache; connect a sched_domain_shared
> > * instance.
> > */
> > - if (sd->flags & SD_SHARE_PKG_RESOURCES) {
> > + if (sd->flags & SD_SHARE_LLC) {
> > sd->shared = *per_cpu_ptr(sdd->sds, sd_id);
> > atomic_inc(&sd->shared->ref);
> > atomic_set(&sd->shared->nr_busy_cpus, sd_weight);
> > @@ -2446,8 +2446,8 @@ build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *att
> > for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
> > struct sched_domain *child = sd->child;
> >
> > - if (!(sd->flags & SD_SHARE_PKG_RESOURCES) && child &&
> > - (child->flags & SD_SHARE_PKG_RESOURCES)) {
> > + if (!(sd->flags & SD_SHARE_LLC) && child &&
> > + (child->flags & SD_SHARE_LLC)) {
> > struct sched_domain __rcu *top_p;
> > unsigned int nr_llcs;
> >
> > --
> > 2.43.0
> >
> >
>
> Thanks
> Barry