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fs/proc/task_mmu.c: add user-space support for resetting mm->hiwater_rss (peak RSS)

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Peak resident size of a process can be reset back to the process's
current rss value 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.

Origin:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=695f055936938c674473ea071ca7359a863551e7

[akpm@linux-foundation.org: clarify behaviour in documentation]
Signed-off-by: Petr Cermak <petrcermak@chromium.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Primiano Tucci <primiano@chromium.org>
Cc: Petr Cermak <petrcermak@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Change-Id: I543a7640639d9916e813af875003fe3ee3a6bfe0
This commit is contained in:
Petr Cermak 2015-02-18 10:39:10 +00:00 committed by JP Abgrall
parent 428e6d675d
commit 740006ef28
3 changed files with 25 additions and 1 deletions
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4
Documentation/filesystems/proc.txt
View File

@ -490,6 +490,10 @@ To clear the bits for the file mapped pages associated with the process
> echo 3 > /proc/PID/clear_refs
Any other value written to /proc/PID/clear_refs will have no effect.
To reset the peak resident set size ("high water mark") to the process's
current value:
> echo 5 > /proc/PID/clear_refs
The /proc/pid/pagemap gives the PFN, which can be used to find the pageflags
using /proc/kpageflags and number of times a page is mapped using
/proc/kpagecount. For detailed explanation, see Documentation/vm/pagemap.txt.

17
fs/proc/task_mmu.c
View File

@ -784,6 +784,7 @@ static int clear_refs_pte_range(pmd_t *pmd, unsigned long addr,
#define CLEAR_REFS_ALL 1
#define CLEAR_REFS_ANON 2
#define CLEAR_REFS_MAPPED 3
#define CLEAR_REFS_MM_HIWATER_RSS 5
static ssize_t clear_refs_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
@ -803,7 +804,8 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
rv = kstrtoint(strstrip(buffer), 10, &type);
if (rv < 0)
return rv;
if (type < CLEAR_REFS_ALL || type > CLEAR_REFS_MAPPED)
if ((type < CLEAR_REFS_ALL || type > CLEAR_REFS_MAPPED) &&
type != CLEAR_REFS_MM_HIWATER_RSS)
return -EINVAL;
task = get_proc_task(file_inode(file));
if (!task)
@ -814,6 +816,18 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
.pmd_entry = clear_refs_pte_range,
.mm = mm,
};
if (type == CLEAR_REFS_MM_HIWATER_RSS) {
/*
* Writing 5 to /proc/pid/clear_refs resets the peak
* resident set size to this mm's current rss value.
*/
down_write(&mm->mmap_sem);
reset_mm_hiwater_rss(mm);
up_write(&mm->mmap_sem);
goto out_mm;
}
down_read(&mm->mmap_sem);
for (vma = mm->mmap; vma; vma = vma->vm_next) {
clear_refs_walk.private = vma;
@ -837,6 +851,7 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
}
flush_tlb_mm(mm);
up_read(&mm->mmap_sem);
out_mm:
mmput(mm);
}
put_task_struct(task);

5
include/linux/mm.h
View File

@ -1166,6 +1166,11 @@ 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)
{