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Message-Id: <20240512193657.79298-2-sj@kernel.org>
Date: Sun, 12 May 2024 12:36:52 -0700
From: SeongJae Park <sj@...nel.org>
To:
Cc: SeongJae Park <sj@...nel.org>,
damon@...ts.linux.dev,
linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Subject: [RFC IDEA v2 1/6] mm/damon: implement DAMOS actions for access-aware contiguous memory allocation
Implement two DAMOS actions, namely DAMOS_ALLOC and DAMOS_FREE. As the
name says, the actions allocate/de-allocate given DAMOS target memory in
user-defined base granularity.
Signed-off-by: SeongJae Park <sj@...nel.org>
---
include/linux/damon.h | 37 ++++++++++++++++
mm/damon/paddr.c | 93 ++++++++++++++++++++++++++++++++++++++++
mm/damon/sysfs-schemes.c | 4 ++
3 files changed, 134 insertions(+)
diff --git a/include/linux/damon.h b/include/linux/damon.h
index 0c3f93374e8d..933bc7777f2d 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -107,6 +107,11 @@ struct damon_target {
* @DAMOS_LRU_DEPRIO: Deprioritize the region on its LRU lists.
* @DAMOS_MIGRATE_HOT: Migrate the regions prioritizing warmer regions.
* @DAMOS_MIGRATE_COLD: Migrate the regions prioritizing colder regions.
+#ifdef CONFIG_ACMA
+ * @DAMOS_ALLOC: Allocate pages in the region,
+ * &struct damos->alloc_order pages at once.
+ * @DAMOS_FREE: Return DAMOS_ALLOC-ed pages back to the system.
+#endif
* @DAMOS_STAT: Do nothing but count the stat.
* @NR_DAMOS_ACTIONS: Total number of DAMOS actions
*
@@ -126,6 +131,10 @@ enum damos_action {
DAMOS_LRU_DEPRIO,
DAMOS_MIGRATE_HOT,
DAMOS_MIGRATE_COLD,
+#ifdef CONFIG_ACMA
+ DAMOS_ALLOC,
+ DAMOS_FREE,
+#endif
DAMOS_STAT, /* Do nothing but only record the stat */
NR_DAMOS_ACTIONS,
};
@@ -375,6 +384,11 @@ struct damos_access_pattern {
* struct damos - Represents a Data Access Monitoring-based Operation Scheme.
* @pattern: Access pattern of target regions.
* @action: &damo_action to be applied to the target regions.
+#ifdef CONFIG_ACMA
+ * @alloc_order: DAMOS_ALLOC/FREE applying granularity.
+ * @alloc_callback: DAMOS_ALLOC success callback.
+ * @free_callback: DAMOS_FREE callback.
+#endif
* @apply_interval_us: The time between applying the @action.
* @quota: Control the aggressiveness of this scheme.
* @wmarks: Watermarks for automated (in)activation of this scheme.
@@ -388,6 +402,18 @@ struct damos_access_pattern {
* CPU time or IO resources for the &action, "a is used.
*
* If @apply_interval_us is zero, &damon_attrs->aggr_interval is used instead.
+#ifdef CONFIG_ACMA
+ *
+ * If @action is CONFIG_ALLOC or CONFIG_FREE, the action is applied to
+ * @alloc_order pages of the region at once. For example, if the region has
+ * 1024 pages, and @alloc_order is 9, DAMOS tries to allocate or free first 512
+ * (2^9) contiguous pages at once, and then next 512 pages.
+ *
+ * For each success of such allocation attemp, @alloc_callback is called back.
+ * For each attempt of deallocation, @free_callback is called back first,
+ * before trying the deallocation. If @free_callback returns non-zero, the
+ * deallocation attempt is aborted.
+#endif
*
* To do the work only when needed, schemes can be activated for specific
* system situations using &wmarks. If all schemes that registered to the
@@ -409,6 +435,11 @@ struct damos_access_pattern {
struct damos {
struct damos_access_pattern pattern;
enum damos_action action;
+#ifdef CONFIG_ACMA
+ unsigned int alloc_order;
+ int (*alloc_callback)(unsigned long start_addr);
+ int (*free_callback)(unsigned long start_addr);
+#endif
unsigned long apply_interval_us;
/* private: internal use only */
/*
@@ -784,6 +815,12 @@ int damon_stop(struct damon_ctx **ctxs, int nr_ctxs);
int damon_set_region_biggest_system_ram_default(struct damon_target *t,
unsigned long *start, unsigned long *end);
+#ifdef CONFIG_ACMA
+
+unsigned long damon_alloced_bytes(void);
+
+#endif
+
#endif /* CONFIG_DAMON */
#endif /* _DAMON_H */
diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index 81163206e70c..f66bd032c523 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -475,6 +475,93 @@ static unsigned long damon_pa_migrate(struct damon_region *r, struct damos *s)
}
+#ifdef CONFIG_ACMA
+
+static bool damon_pa_preempted(unsigned long pfn)
+{
+ /* todo: implement */
+}
+
+/* always success for preempted=false */
+static int damon_pa_set_preempted(unsigned long pfn, bool preempted)
+{
+ /* todo: implement */
+}
+
+/*
+ * Return ownership of the memory to the system. At the moment, only user of
+ * this function is virtio-balloon. They could use page fault-based mechanisms
+ * to catch returned ownership. Therefore this function doesn't notify this
+ * event to the report subscribers. In future, we could add some notification
+ * system of this event for more users such as contig memory allocator.
+ */
+static int damon_pa_free(unsigned long pfn, struct damos *scheme)
+{
+ if (!damon_pa_preemted(pfn))
+ return -EINVAL;
+
+ free_contig_range(pfn, DAMON_MEM_PREEMPT_PAGES);
+ damon_pa_set_preempted(pfn, false);
+ /*
+ * We intentionally do not report this event to the preempted memory
+ * report subscriber. They could use page fault handler like
+ * mechanisms.
+ */
+ return 0;
+}
+
+/*
+ * Pass ownership of the memory to page reporting subscribers. The subscribers
+ * can use the reported memory for their purpose, e.g., letting Host
+ * re-allocate it to other guest, or use as contig allocation memory pool.
+ */
+static int damon_pa_alloc(unsigned long pfn, struct damos *scheme)
+{
+ int err;
+
+ if (damon_pa_preempted(pfn))
+ return -EINVAL;
+ if (alloc_contig_range(pfn, pfn + DAMON_MEM_PREEMPT_PAGES,
+ MIGRATE_MOVABLE, GFP_KERNEL))
+ return -ENOMEM;
+ err = damon_pa_set_preempted(pfn, true);
+ if (err) {
+ free_contig_range(pfn, DAMON_MEM_PREEMPT_PAGES);
+ return err;
+ }
+ if (!scheme->alloc_callback)
+ return 0;
+ err = scheme->alloc_callback(PFN_PHYS(pfn));
+ if (err) {
+ damon_pa_free(pfn);
+ return err;
+ }
+ return 0;
+}
+
+/* Preempt or yield memory regions from system */
+static unsigned long damon_pa_alloc_or_free(
+ struct damon_region *r, struct damos *s, bool alloc)
+{
+ unsigned long pfn;
+ unsigned long applied = 0;
+
+ for (pfn = PHYS_PFN(r->start); pfn < PHYS_PFN(r->end);
+ pfn += DAMON_MEM_PREEMPT_PAGES) {
+ if (alloc) {
+ if (damon_pa_alloc(pfn, s))
+ continue;
+ } else {
+ if (damon_pa_free(pfn, s))
+ continue;
+ }
+ applied += 1;
+ }
+ return applied * PAGE_SIZE * DAMON_MEM_PREEMPT_PAGES;
+}
+
+#endif
+
static unsigned long damon_pa_apply_scheme(struct damon_ctx *ctx,
struct damon_target *t, struct damon_region *r,
struct damos *scheme)
@@ -489,6 +576,12 @@ static unsigned long damon_pa_apply_scheme(struct damon_ctx *ctx,
case DAMOS_MIGRATE_HOT:
case DAMOS_MIGRATE_COLD:
return damon_pa_migrate(r, scheme);
+#ifdef CONFIG_ACMA
+ case DAMOS_ALLOC:
+ return damon_pa_alloc_or_free(r, scheme, true);
+ case DAMOS_FREE:
+ return damon_pa_alloc_or_free(r, scheme, false);
+#endif
case DAMOS_STAT:
break;
default:
diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 66fccfa776d7..54be4d661881 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -1460,6 +1460,10 @@ static const char * const damon_sysfs_damos_action_strs[] = {
"lru_deprio",
"migrate_hot",
"migrate_cold",
+#ifdef CONFIG_ACMA
+ "damos_alloc",
+ "damos_free",
+#endif
"stat",
};
--
2.39.2
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