Peak resident size of a process can be reset by writing "5" to
/proc/pid/clear_refs. The driving use-case for this would be getting the
peak RSS value, which can be retrieved from the VmHWM field in
/proc/pid/status, per benchmark iteration or test scenario.
Signed-off-by: Petr Cermak <petrcer...@chromium.org>
---
Documentation/filesystems/proc.txt | 3 +++
fs/proc/task_mmu.c | 15 ++++++++++++++-
include/linux/mm.h | 5 +++++
3 files changed, 22 insertions(+), 1 deletion(-)
diff --git a/Documentation/filesystems/proc.txt
b/Documentation/filesystems/proc.txt
index aae9dd1..7a3c689 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -488,6 +488,9 @@ To clear the bits for the file mapped pages associated with
the process
To clear the soft-dirty bit
> echo 4 > /proc/PID/clear_refs
+To reset the peak resident set size ("high water mark") to the current value
+ > echo 5 > /proc/PID/clear_refs
+
Any other value written to /proc/PID/clear_refs will have no effect.
The /proc/pid/pagemap gives the PFN, which can be used to find the pageflags
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 500d310..881a708 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -747,6 +747,7 @@ enum clear_refs_types {
CLEAR_REFS_ANON,
CLEAR_REFS_MAPPED,
CLEAR_REFS_SOFT_DIRTY,
+ CLEAR_REFS_MM_HIWATER_RSS,
CLEAR_REFS_LAST,
};
@@ -857,6 +858,17 @@ static ssize_t clear_refs_write(struct file *file, const
char __user *buf,
if (!mm)
goto out_task;
+ if (type == CLEAR_REFS_MM_HIWATER_RSS) {
+ /*
+ * Writing 5 to /proc/pid/clear_refs resets the peak resident
+ * set size to the current value.
+ */
+ down_write(&mm->mmap_sem);
+ reset_mm_hiwater_rss(mm);
+ up_write(&mm->mmap_sem);
+ goto out_mm;
+ }
+
cp = (struct clear_refs_private) {
.type = type
};
@@ -906,8 +918,9 @@ static ssize_t clear_refs_write(struct file *file, const
char __user *buf,
mmu_notifier_invalidate_range_end(mm, 0, -1);
flush_tlb_mm(mm);
up_read(&mm->mmap_sem);
- mmput(mm);
+out_mm:
+ mmput(mm);
out_task:
put_task_struct(task);
diff --git a/include/linux/mm.h b/include/linux/mm.h
index f80d019..dabb6cd 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1366,6 +1366,11 @@ static inline void update_hiwater_vm(struct mm_struct
*mm)
mm->hiwater_vm = mm->total_vm;
}
+static inline void reset_mm_hiwater_rss(struct mm_struct *mm)
+{
+ mm->hiwater_rss = get_mm_rss(mm);
+}
+
static inline void setmax_mm_hiwater_rss(unsigned long *maxrss,
struct mm_struct *mm)
{
--
2.2.0.rc0.207.ga3a616c
--
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