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Message-ID: <20250813050706.1564229-13-yanquanmin1@huawei.com>
Date: Wed, 13 Aug 2025 13:07:02 +0800
From: Quanmin Yan <yanquanmin1@...wei.com>
To: <sj@...nel.org>
CC: <akpm@...ux-foundation.org>, <damon@...ts.linux.dev>,
<linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
<yanquanmin1@...wei.com>, <wangkefeng.wang@...wei.com>, <zuoze1@...wei.com>
Subject: [RFC PATCH -next 12/16] mm/damon: add damon_ctx->min_region and damon_target->min_region
Adopting addr_unit would make DAMON_MINREGION 'addr_unit * 4096'
bytes and cause data alignment issues[1].
Add damon_ctx->min_region to change DAMON_MIN_REGION from a global
macro value to per-context variable, let target inherit the min_region
from its associated ctx to avoid excessive passing of ctx.
[1] https://lore.kernel.org/all/527714dd-0e33-43ab-bbbd-d89670ba79e7@huawei.com
Signed-off-by: Quanmin Yan <yanquanmin1@...wei.com>
---
include/linux/damon.h | 7 ++++++-
mm/damon/core.c | 41 +++++++++++++++++++++++++++--------------
2 files changed, 33 insertions(+), 15 deletions(-)
diff --git a/include/linux/damon.h b/include/linux/damon.h
index 1b7b4cf1a3c5..aa045dcb5b5d 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -88,6 +88,7 @@ struct damon_region {
/**
* struct damon_target - Represents a monitoring target.
* @pid: The PID of the virtual address space to monitor.
+ * @min_region: Minimum Region Size.
* @nr_regions: Number of monitoring target regions of this target.
* @regions_list: Head of the monitoring target regions of this target.
* @list: List head for siblings.
@@ -95,10 +96,12 @@ struct damon_region {
* Each monitoring context could have multiple targets. For example, a context
* for virtual memory address spaces could have multiple target processes. The
* @pid should be set for appropriate &struct damon_operations including the
- * virtual address spaces monitoring operations.
+ * virtual address spaces monitoring operations. The @min_region Keeps consistent
+ * with the associated monitoring context.
*/
struct damon_target {
struct pid *pid;
+ unsigned long min_region;
unsigned int nr_regions;
struct list_head regions_list;
struct list_head list;
@@ -747,6 +750,7 @@ struct damon_attrs {
*
* @ops: Set of monitoring operations for given use cases.
* @addr_unit: Scale factor for core to ops address conversion.
+ * @min_region: Minimum Region Size.
* @adaptive_targets: Head of monitoring targets (&damon_target) list.
* @schemes: Head of schemes (&damos) list.
*/
@@ -789,6 +793,7 @@ struct damon_ctx {
struct damon_operations ops;
unsigned long addr_unit;
+ unsigned long min_region;
struct list_head adaptive_targets;
struct list_head schemes;
diff --git a/mm/damon/core.c b/mm/damon/core.c
index 803c30f64b94..b162aa1156fc 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -245,16 +245,16 @@ int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges,
/* no region intersects with this range */
newr = damon_new_region(
ALIGN_DOWN(range->start,
- DAMON_MIN_REGION),
- ALIGN(range->end, DAMON_MIN_REGION));
+ t->min_region),
+ ALIGN(range->end, t->min_region));
if (!newr)
return -ENOMEM;
damon_insert_region(newr, damon_prev_region(r), r, t);
} else {
/* resize intersecting regions to fit in this range */
first->ar.start = ALIGN_DOWN(range->start,
- DAMON_MIN_REGION);
- last->ar.end = ALIGN(range->end, DAMON_MIN_REGION);
+ t->min_region);
+ last->ar.end = ALIGN(range->end, t->min_region);
/* fill possible holes in the range */
err = damon_fill_regions_holes(first, last, t);
@@ -472,6 +472,7 @@ struct damon_target *damon_new_target(void)
t->pid = NULL;
t->nr_regions = 0;
+ t->min_region = DAMON_MIN_REGION;
INIT_LIST_HEAD(&t->regions_list);
INIT_LIST_HEAD(&t->list);
@@ -480,6 +481,7 @@ struct damon_target *damon_new_target(void)
void damon_add_target(struct damon_ctx *ctx, struct damon_target *t)
{
+ t->min_region = ctx->min_region;
list_add_tail(&t->list, &ctx->adaptive_targets);
}
@@ -545,6 +547,7 @@ struct damon_ctx *damon_new_ctx(void)
ctx->attrs.max_nr_regions = 1000;
ctx->addr_unit = 1;
+ ctx->min_region = DAMON_MIN_REGION;
INIT_LIST_HEAD(&ctx->adaptive_targets);
INIT_LIST_HEAD(&ctx->schemes);
@@ -1181,6 +1184,14 @@ static int damon_commit_targets(
return 0;
}
+static void damon_sync_target_min_region(struct damon_ctx *ctx)
+{
+ struct damon_target *t;
+
+ damon_for_each_target(t, ctx)
+ t->min_region = ctx->min_region;
+}
+
/**
* damon_commit_ctx() - Commit parameters of a DAMON context to another.
* @dst: The commit destination DAMON context.
@@ -1216,6 +1227,8 @@ int damon_commit_ctx(struct damon_ctx *dst, struct damon_ctx *src)
return err;
dst->ops = src->ops;
dst->addr_unit = src->addr_unit ? : 1;
+ dst->min_region = max(DAMON_MIN_REGION / dst->addr_unit, 1);
+ damon_sync_target_min_region(dst);
return 0;
}
@@ -1248,8 +1261,8 @@ static unsigned long damon_region_sz_limit(struct damon_ctx *ctx)
if (ctx->attrs.min_nr_regions)
sz /= ctx->attrs.min_nr_regions;
- if (sz < DAMON_MIN_REGION)
- sz = DAMON_MIN_REGION;
+ if (sz < ctx->min_region)
+ sz = ctx->min_region;
return sz;
}
@@ -1632,11 +1645,11 @@ static bool damos_skip_charged_region(struct damon_target *t,
if (quota->charge_addr_from && r->ar.start <
quota->charge_addr_from) {
sz_to_skip = ALIGN_DOWN(quota->charge_addr_from -
- r->ar.start, DAMON_MIN_REGION);
+ r->ar.start, t->min_region);
if (!sz_to_skip) {
- if (damon_sz_region(r) <= DAMON_MIN_REGION)
+ if (damon_sz_region(r) <= t->min_region)
return true;
- sz_to_skip = DAMON_MIN_REGION;
+ sz_to_skip = t->min_region;
}
damon_split_region_at(t, r, sz_to_skip);
r = damon_next_region(r);
@@ -1678,8 +1691,8 @@ static bool damos_filter_match(struct damon_ctx *ctx, struct damon_target *t,
matched = target_idx == filter->target_idx;
break;
case DAMOS_FILTER_TYPE_ADDR:
- start = ALIGN_DOWN(filter->addr_range.start, DAMON_MIN_REGION);
- end = ALIGN_DOWN(filter->addr_range.end, DAMON_MIN_REGION);
+ start = ALIGN_DOWN(filter->addr_range.start, t->min_region);
+ end = ALIGN_DOWN(filter->addr_range.end, t->min_region);
/* inside the range */
if (start <= r->ar.start && r->ar.end <= end) {
@@ -1850,7 +1863,7 @@ static void damos_apply_scheme(struct damon_ctx *c, struct damon_target *t,
if (c->ops.apply_scheme) {
if (quota->esz && quota->charged_sz + sz > quota->esz) {
sz = ALIGN_DOWN(quota->esz - quota->charged_sz,
- DAMON_MIN_REGION);
+ c->min_region);
if (!sz)
goto update_stat;
damon_split_region_at(t, r, sz);
@@ -2302,13 +2315,13 @@ static void damon_split_regions_of(struct damon_target *t, int nr_subs)
sz_region = damon_sz_region(r);
for (i = 0; i < nr_subs - 1 &&
- sz_region > 2 * DAMON_MIN_REGION; i++) {
+ sz_region > 2 * t->min_region; i++) {
/*
* Randomly select size of left sub-region to be at
* least 10 percent and at most 90% of original region
*/
sz_sub = ALIGN_DOWN(damon_rand(1, 10) *
- sz_region / 10, DAMON_MIN_REGION);
+ sz_region / 10, t->min_region);
/* Do not allow blank region */
if (sz_sub == 0 || sz_sub >= sz_region)
continue;
--
2.34.1
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