"Ho-Ren (Jack) Chuang" <horenchuang@xxxxxxxxxxxxx> writes:
> On Tue, Mar 12, 2024 at 2:21 AM Huang, Ying <ying.huang@xxxxxxxxx> wrote:
>>
>> "Ho-Ren (Jack) Chuang" <horenchuang@xxxxxxxxxxxxx> writes:
>>
>> > The current implementation treats emulated memory devices, such as
>> > CXL1.1 type3 memory, as normal DRAM when they are emulated as normal memory
>> > (E820_TYPE_RAM). However, these emulated devices have different
>> > characteristics than traditional DRAM, making it important to
>> > distinguish them. Thus, we modify the tiered memory initialization process
>> > to introduce a delay specifically for CPUless NUMA nodes. This delay
>> > ensures that the memory tier initialization for these nodes is deferred
>> > until HMAT information is obtained during the boot process. Finally,
>> > demotion tables are recalculated at the end.
>> >
>> > * Abstract common functions into `find_alloc_memory_type()`
>>
>> We should move kmem_put_memory_types() (renamed to
>> mt_put_memory_types()?) too. This can be put in a separate patch.
>>
>
> Will do! Thanks,
>
>
>>
>> > Since different memory devices require finding or allocating a memory type,
>> > these common steps are abstracted into a single function,
>> > `find_alloc_memory_type()`, enhancing code scalability and conciseness.
>> >
>> > * Handle cases where there is no HMAT when creating memory tiers
>> > There is a scenario where a CPUless node does not provide HMAT information.
>> > If no HMAT is specified, it falls back to using the default DRAM tier.
>> >
>> > * Change adist calculation code to use another new lock, mt_perf_lock.
>> > In the current implementation, iterating through CPUlist nodes requires
>> > holding the `memory_tier_lock`. However, `mt_calc_adistance()` will end up
>> > trying to acquire the same lock, leading to a potential deadlock.
>> > Therefore, we propose introducing a standalone `mt_perf_lock` to protect
>> > `default_dram_perf`. This approach not only avoids deadlock but also
>> > prevents holding a large lock simultaneously.
>> >
>> > Signed-off-by: Ho-Ren (Jack) Chuang <horenchuang@xxxxxxxxxxxxx>
>> > Signed-off-by: Hao Xiang <hao.xiang@xxxxxxxxxxxxx>
>> > ---
>> > drivers/acpi/numa/hmat.c | 11 ++++++
>> > drivers/dax/kmem.c | 13 +------
>> > include/linux/acpi.h | 6 ++++
>> > include/linux/memory-tiers.h | 8 +++++
>> > mm/memory-tiers.c | 70 +++++++++++++++++++++++++++++++++---
>> > 5 files changed, 92 insertions(+), 16 deletions(-)
>> >
>> > diff --git a/drivers/acpi/numa/hmat.c b/drivers/acpi/numa/hmat.c
>> > index d6b85f0f6082..28812ec2c793 100644
>> > --- a/drivers/acpi/numa/hmat.c
>> > +++ b/drivers/acpi/numa/hmat.c
>> > @@ -38,6 +38,8 @@ static LIST_HEAD(targets);
>> > static LIST_HEAD(initiators);
>> > static LIST_HEAD(localities);
>> >
>> > +static LIST_HEAD(hmat_memory_types);
>> > +
>>
>> HMAT isn't a device driver for some memory devices. So I don't think we
>> should manage memory types in HMAT.
>
> I can put it back in memory-tier.c. How about the list? Do we still
> need to keep a separate list for storing late_inited memory nodes?
> And how about the list name if we need to remove the prefix "hmat_"?
I don't think we need a separate list for memory-less nodes. Just
iterate all memory-less nodes.
>
>> Instead, if the memory_type of a
>> node isn't set by the driver, we should manage it in memory-tier.c as
>> fallback.
>>
>
> Do you mean some device drivers may init memory tiers between
> memory_tier_init() and late_initcall(memory_tier_late_init);?
> And this is the reason why you mention to exclude
> "node_memory_types[nid].memtype != NULL" in memory_tier_late_init().
> Is my understanding correct?
Yes.
>> > static DEFINE_MUTEX(target_lock);
>> >
>> > /*
>> > @@ -149,6 +151,12 @@ int acpi_get_genport_coordinates(u32 uid,
>> > }
>> > EXPORT_SYMBOL_NS_GPL(acpi_get_genport_coordinates, CXL);
>> >
>> > +struct memory_dev_type *hmat_find_alloc_memory_type(int adist)
>> > +{
>> > + return find_alloc_memory_type(adist, &hmat_memory_types);
>> > +}
>> > +EXPORT_SYMBOL_GPL(hmat_find_alloc_memory_type);
>> > +
>> > static __init void alloc_memory_initiator(unsigned int cpu_pxm)
>> > {
>> > struct memory_initiator *initiator;
>> > @@ -1038,6 +1046,9 @@ static __init int hmat_init(void)
>> > if (!hmat_set_default_dram_perf())
>> > register_mt_adistance_algorithm(&hmat_adist_nb);
>> >
>> > + /* Post-create CPUless memory tiers after getting HMAT info */
>> > + memory_tier_late_init();
>> > +
>>
>> This should be called in memory-tier.c via
>>
>> late_initcall(memory_tier_late_init);
>>
>> Then, we don't need hmat to call it.
>>
>
> Thanks. Learned!
>
>
>> > return 0;
>> > out_put:
>> > hmat_free_structures();
>> > diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
>> > index 42ee360cf4e3..aee17ab59f4f 100644
>> > --- a/drivers/dax/kmem.c
>> > +++ b/drivers/dax/kmem.c
>> > @@ -55,21 +55,10 @@ static LIST_HEAD(kmem_memory_types);
>> >
>> > static struct memory_dev_type *kmem_find_alloc_memory_type(int adist)
>> > {
>> > - bool found = false;
>> > struct memory_dev_type *mtype;
>> >
>> > mutex_lock(&kmem_memory_type_lock);
>> > - list_for_each_entry(mtype, &kmem_memory_types, list) {
>> > - if (mtype->adistance == adist) {
>> > - found = true;
>> > - break;
>> > - }
>> > - }
>> > - if (!found) {
>> > - mtype = alloc_memory_type(adist);
>> > - if (!IS_ERR(mtype))
>> > - list_add(&mtype->list, &kmem_memory_types);
>> > - }
>> > + mtype = find_alloc_memory_type(adist, &kmem_memory_types);
>> > mutex_unlock(&kmem_memory_type_lock);
>> >
>> > return mtype;
>> > diff --git a/include/linux/acpi.h b/include/linux/acpi.h
>> > index b7165e52b3c6..3f927ff01f02 100644
>> > --- a/include/linux/acpi.h
>> > +++ b/include/linux/acpi.h
>> > @@ -434,12 +434,18 @@ int thermal_acpi_critical_trip_temp(struct acpi_device *adev, int *ret_temp);
>> >
>> > #ifdef CONFIG_ACPI_HMAT
>> > int acpi_get_genport_coordinates(u32 uid, struct access_coordinate *coord);
>> > +struct memory_dev_type *hmat_find_alloc_memory_type(int adist);
>> > #else
>> > static inline int acpi_get_genport_coordinates(u32 uid,
>> > struct access_coordinate *coord)
>> > {
>> > return -EOPNOTSUPP;
>> > }
>> > +
>> > +static inline struct memory_dev_type *hmat_find_alloc_memory_type(int adist)
>> > +{
>> > + return NULL;
>> > +}
>> > #endif
>> >
>> > #ifdef CONFIG_ACPI_NUMA
>> > diff --git a/include/linux/memory-tiers.h b/include/linux/memory-tiers.h
>> > index 69e781900082..4bc2596c5774 100644
>> > --- a/include/linux/memory-tiers.h
>> > +++ b/include/linux/memory-tiers.h
>> > @@ -48,6 +48,9 @@ int mt_calc_adistance(int node, int *adist);
>> > int mt_set_default_dram_perf(int nid, struct access_coordinate *perf,
>> > const char *source);
>> > int mt_perf_to_adistance(struct access_coordinate *perf, int *adist);
>> > +struct memory_dev_type *find_alloc_memory_type(int adist,
>> > + struct list_head *memory_types);
>> > +void memory_tier_late_init(void);
>> > #ifdef CONFIG_MIGRATION
>> > int next_demotion_node(int node);
>> > void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets);
>> > @@ -136,5 +139,10 @@ static inline int mt_perf_to_adistance(struct access_coordinate *perf, int *adis
>> > {
>> > return -EIO;
>> > }
>> > +
>> > +static inline void memory_tier_late_init(void)
>> > +{
>> > +
>> > +}
>> > #endif /* CONFIG_NUMA */
>> > #endif /* _LINUX_MEMORY_TIERS_H */
>> > diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c
>> > index 0537664620e5..79f748d60e6f 100644
>> > --- a/mm/memory-tiers.c
>> > +++ b/mm/memory-tiers.c
>> > @@ -6,6 +6,7 @@
>> > #include <linux/memory.h>
>> > #include <linux/memory-tiers.h>
>> > #include <linux/notifier.h>
>> > +#include <linux/acpi.h>
>> >
>> > #include "internal.h"
>> >
>> > @@ -35,6 +36,7 @@ struct node_memory_type_map {
>> > };
>> >
>> > static DEFINE_MUTEX(memory_tier_lock);
>> > +static DEFINE_MUTEX(mt_perf_lock);
>>
>> Please add comments about what it protects. And put it near the data
>> structure it protects.
>>
>
> Where is better for me to add comments for this? Code? Patch description?
> Will put it closer to the protected data. Thanks.
Just put the comments at the above of the lock in the source code.
>
>
>> > static LIST_HEAD(memory_tiers);
>> > static struct node_memory_type_map node_memory_types[MAX_NUMNODES];
>> > struct memory_dev_type *default_dram_type;
>> > @@ -623,6 +625,58 @@ void clear_node_memory_type(int node, struct memory_dev_type *memtype)
>> > }
>> > EXPORT_SYMBOL_GPL(clear_node_memory_type);
>> >
>> > +struct memory_dev_type *find_alloc_memory_type(int adist, struct list_head *memory_types)
>> > +{
>> > + bool found = false;
>> > + struct memory_dev_type *mtype;
>> > +
>> > + list_for_each_entry(mtype, memory_types, list) {
>> > + if (mtype->adistance == adist) {
>> > + found = true;
>> > + break;
>> > + }
>> > + }
>> > + if (!found) {
>> > + mtype = alloc_memory_type(adist);
>> > + if (!IS_ERR(mtype))
>> > + list_add(&mtype->list, memory_types);
>> > + }
>> > +
>> > + return mtype;
>> > +}
>> > +EXPORT_SYMBOL_GPL(find_alloc_memory_type);
>> > +
>> > +static void memory_tier_late_create(int node)
>> > +{
>> > + struct memory_dev_type *mtype = NULL;
>> > + int adist = MEMTIER_ADISTANCE_DRAM;
>> > +
>> > + mt_calc_adistance(node, &adist);
>> > + if (adist != MEMTIER_ADISTANCE_DRAM) {
>>
>> We can manage default_dram_type() via find_alloc_memory_type()
>> too.
>>
>> And, if "node_memory_types[node].memtype == NULL", we can call
>> mt_calc_adistance(node, &adist) and find_alloc_memory_type() in
>> set_node_memory_tier(). Then, we can cover hotpluged memory node too.
>>
>> > + mtype = hmat_find_alloc_memory_type(adist);
>> > + if (!IS_ERR(mtype))
>> > + __init_node_memory_type(node, mtype);
>> > + else
>> > + pr_err("Failed to allocate a memory type at %s()\n", __func__);
>> > + }
>> > +
>> > + set_node_memory_tier(node);
>> > +}
>> > +
>> > +void memory_tier_late_init(void)
>> > +{
>> > + int nid;
>> > +
>> > + mutex_lock(&memory_tier_lock);
>> > + for_each_node_state(nid, N_MEMORY)
>> > + if (!node_state(nid, N_CPU))
>>
>> We should exclude "node_memory_types[nid].memtype != NULL". Some memory
>> nodes may be onlined by some device drivers and setup memory tiers
>> already.
>>
>> > + memory_tier_late_create(nid);
>> > +
>> > + establish_demotion_targets();
>> > + mutex_unlock(&memory_tier_lock);
>> > +}
>> > +EXPORT_SYMBOL_GPL(memory_tier_late_init);
>> > +
>> > static void dump_hmem_attrs(struct access_coordinate *coord, const char *prefix)
>> > {
>> > pr_info(
>> > @@ -636,7 +690,7 @@ int mt_set_default_dram_perf(int nid, struct access_coordinate *perf,
>> > {
>> > int rc = 0;
>> >
>> > - mutex_lock(&memory_tier_lock);
>> > + mutex_lock(&mt_perf_lock);
>> > if (default_dram_perf_error) {
>> > rc = -EIO;
>> > goto out;
>> > @@ -684,7 +738,7 @@ int mt_set_default_dram_perf(int nid, struct access_coordinate *perf,
>> > }
>> >
>> > out:
>> > - mutex_unlock(&memory_tier_lock);
>> > + mutex_unlock(&mt_perf_lock);
>> > return rc;
>> > }
>> >
>> > @@ -700,7 +754,7 @@ int mt_perf_to_adistance(struct access_coordinate *perf, int *adist)
>> > perf->read_bandwidth + perf->write_bandwidth == 0)
>> > return -EINVAL;
>> >
>> > - mutex_lock(&memory_tier_lock);
>> > + mutex_lock(&mt_perf_lock);
>> > /*
>> > * The abstract distance of a memory node is in direct proportion to
>> > * its memory latency (read + write) and inversely proportional to its
>> > @@ -713,7 +767,7 @@ int mt_perf_to_adistance(struct access_coordinate *perf, int *adist)
>> > (default_dram_perf.read_latency + default_dram_perf.write_latency) *
>> > (default_dram_perf.read_bandwidth + default_dram_perf.write_bandwidth) /
>> > (perf->read_bandwidth + perf->write_bandwidth);
>> > - mutex_unlock(&memory_tier_lock);
>> > + mutex_unlock(&mt_perf_lock);
>> >
>> > return 0;
>> > }
>> > @@ -836,6 +890,14 @@ static int __init memory_tier_init(void)
>> > * types assigned.
>> > */
>> > for_each_node_state(node, N_MEMORY) {
>> > + if (!node_state(node, N_CPU))
>> > + /*
>> > + * Defer memory tier initialization on CPUless numa nodes.
>> > + * These will be initialized when HMAT information is
>>
>> HMAT is platform specific, we should avoid to mention it in general code
>> if possible.
>>
>
> Will fix! Thanks,
>
>
>> > + * available.
>> > + */
>> > + continue;
>> > +
>> > memtier = set_node_memory_tier(node);
>> > if (IS_ERR(memtier))
>> > /*
>>
--
Best Regards,
Huang, Ying
