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Date: Wed, 16 Feb 2022 16:30:40 +0800
From: Xin Hao <xhao@...ux.alibaba.com>
To: sj@...nel.org
Cc: xhao@...ux.alibaba.com, rongwei.wang@...ux.alibaba.com,
akpm@...ux-foundation.org, linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Subject: [RFC PATCH V1 4/5] mm/damon/dbgfs: Add numa simulate switch
For applications that frequently access the memory area,
Doing numa simulation will cause a lot of pagefault and
tlb misses which will cause the applications performance
regression.
So there adds a switch to turn off the numa simulation
function by default, if you want to turn on this function
just do like below.
# cd /sys/kernel/debug/damon/
# echo on > numa_stat
# cat numa_stat
# on
Signed-off-by: Xin Hao <xhao@...ux.alibaba.com>
Signed-off-by: Rongwei Wang <rongwei.wang@...ux.alibaba.com>
---
include/linux/damon.h | 3 +++
mm/damon/core.c | 10 ++++++++-
mm/damon/dbgfs.c | 52 +++++++++++++++++++++++++++++++++++++++++--
mm/damon/paddr.c | 6 +++--
mm/damon/vaddr.c | 6 +++--
5 files changed, 70 insertions(+), 7 deletions(-)
diff --git a/include/linux/damon.h b/include/linux/damon.h
index 5bf1eb92584b..c7d7613e1a17 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -19,6 +19,9 @@
/* Max priority score for DAMON-based operation schemes */
#define DAMOS_MAX_SCORE (99)
+/* Switch for NUMA fault */
+DECLARE_STATIC_KEY_FALSE(numa_stat_enabled_key);
+
extern struct damon_ctx **dbgfs_ctxs;
extern int dbgfs_nr_ctxs;
diff --git a/mm/damon/core.c b/mm/damon/core.c
index 970fc02abeba..4aa3c2d3895c 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -1060,7 +1060,8 @@ void damon_numa_fault(int page_nid, int node_id, struct vm_fault *vmf)
struct damon_target *t;
struct damon_region *r;
- if (nr_online_nodes > 1) {
+ if (static_branch_unlikely(&numa_stat_enabled_key)
+ && nr_online_nodes > 1) {
t = get_damon_target(current);
if (!t)
return;
@@ -1151,6 +1152,13 @@ static int kdamond_fn(void *data)
nr_running_ctxs--;
mutex_unlock(&damon_lock);
+ /*
+ * when no kdamond threads are running, the
+ * 'numa_stat_enabled_key' keeps default value.
+ */
+ if (!nr_running_ctxs)
+ static_branch_disable(&numa_stat_enabled_key);
+
return 0;
}
diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c
index c7f4e95abc14..0ef35dbfda39 100644
--- a/mm/damon/dbgfs.c
+++ b/mm/damon/dbgfs.c
@@ -609,6 +609,49 @@ static ssize_t dbgfs_kdamond_pid_read(struct file *file,
return len;
}
+DEFINE_STATIC_KEY_FALSE(numa_stat_enabled_key);
+
+static ssize_t dbgfs_numa_stat_read(struct file *file,
+ char __user *buf, size_t count, loff_t *ppos)
+{
+ char numa_on_buf[5];
+ bool enable = static_branch_unlikely(&numa_stat_enabled_key);
+ int len;
+
+ len = scnprintf(numa_on_buf, 5, enable ? "on\n" : "off\n");
+
+ return simple_read_from_buffer(buf, count, ppos, numa_on_buf, len);
+}
+
+static ssize_t dbgfs_numa_stat_write(struct file *file,
+ const char __user *buf, size_t count, loff_t *ppos)
+{
+ ssize_t ret = 0;
+ char *kbuf;
+
+ kbuf = user_input_str(buf, count, ppos);
+ if (IS_ERR(kbuf))
+ return PTR_ERR(kbuf);
+
+ /* Remove white space */
+ if (sscanf(kbuf, "%s", kbuf) != 1) {
+ kfree(kbuf);
+ return -EINVAL;
+ }
+
+ if (!strncmp(kbuf, "on", count))
+ static_branch_enable(&numa_stat_enabled_key);
+ else if (!strncmp(kbuf, "off", count))
+ static_branch_disable(&numa_stat_enabled_key);
+ else
+ ret = -EINVAL;
+
+ if (!ret)
+ ret = count;
+ kfree(kbuf);
+ return ret;
+}
+
static int damon_dbgfs_open(struct inode *inode, struct file *file)
{
file->private_data = inode->i_private;
@@ -645,12 +688,17 @@ static const struct file_operations kdamond_pid_fops = {
.read = dbgfs_kdamond_pid_read,
};
+static const struct file_operations numa_stat_ops = {
+ .write = dbgfs_numa_stat_write,
+ .read = dbgfs_numa_stat_read,
+};
+
static void dbgfs_fill_ctx_dir(struct dentry *dir, struct damon_ctx *ctx)
{
const char * const file_names[] = {"attrs", "schemes", "target_ids",
- "init_regions", "kdamond_pid"};
+ "init_regions", "kdamond_pid", "numa_stat"};
const struct file_operations *fops[] = {&attrs_fops, &schemes_fops,
- &target_ids_fops, &init_regions_fops, &kdamond_pid_fops};
+ &target_ids_fops, &init_regions_fops, &kdamond_pid_fops, &numa_stat_ops};
int i;
for (i = 0; i < ARRAY_SIZE(file_names); i++)
diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index b8feacf15592..9b9920784f22 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -30,14 +30,16 @@ static bool __damon_pa_mk_set(struct page *page, struct vm_area_struct *vma,
addr = pvmw.address;
if (pvmw.pte) {
damon_ptep_mkold(pvmw.pte, vma->vm_mm, addr);
- if (nr_online_nodes > 1) {
+ if (static_branch_unlikely(&numa_stat_enabled_key) &&
+ nr_online_nodes > 1) {
result = damon_ptep_mknone(pvmw.pte, vma, addr);
if (result)
flush_tlb_page(vma, addr);
}
} else {
damon_pmdp_mkold(pvmw.pmd, vma->vm_mm, addr);
- if (nr_online_nodes > 1) {
+ if (static_branch_unlikely(&numa_stat_enabled_key) &&
+ nr_online_nodes > 1) {
result = damon_pmdp_mknone(pvmw.pmd, vma, addr);
if (result) {
unsigned long haddr = addr & HPAGE_PMD_MASK;
diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c
index 78b90972d171..5c2e2c2e29bb 100644
--- a/mm/damon/vaddr.c
+++ b/mm/damon/vaddr.c
@@ -371,7 +371,8 @@ static int damon_va_pmd_entry(pmd_t *pmd, unsigned long addr,
ptl = pmd_lock(walk->mm, pmd);
if (pmd_huge(*pmd)) {
damon_pmdp_mkold(pmd, walk->mm, addr);
- if (nr_online_nodes > 1)
+ if (static_branch_unlikely(&numa_stat_enabled_key) &&
+ nr_online_nodes > 1)
result = damon_pmdp_mknone(pmd, walk->vma, addr);
spin_unlock(ptl);
if (result) {
@@ -392,7 +393,8 @@ static int damon_va_pmd_entry(pmd_t *pmd, unsigned long addr,
return 0;
}
damon_ptep_mkold(pte, walk->mm, addr);
- if (nr_online_nodes > 1)
+ if (static_branch_unlikely(&numa_stat_enabled_key) &&
+ nr_online_nodes > 1)
result = damon_ptep_mknone(pte, walk->vma, addr);
pte_unmap_unlock(pte, ptl);
if (result)
--
2.27.0
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