smaps: add clear_refs file to clear reference
Adds /proc/pid/clear_refs. When any non-zero number is written to this file, pte_mkold() and ClearPageReferenced() is called for each pte and its corresponding page, respectively, in that task's VMAs. This file is only writable by the user who owns the task. It is now possible to measure _approximately_ how much memory a task is using by clearing the reference bits with echo 1 > /proc/pid/clear_refs and checking the reference count for each VMA from the /proc/pid/smaps output at a measured time interval. For example, to observe the approximate change in memory footprint for a task, write a script that clears the references (echo 1 > /proc/pid/clear_refs), sleeps, and then greps for Pgs_Referenced and extracts the size in kB. Add the sizes for each VMA together for the total referenced footprint. Moments later, repeat the process and observe the difference. For example, using an efficient Mozilla: accumulated time referenced memory ---------------- ----------------- 0 s 408 kB 1 s 408 kB 2 s 556 kB 3 s 1028 kB 4 s 872 kB 5 s 1956 kB 6 s 416 kB 7 s 1560 kB 8 s 2336 kB 9 s 1044 kB 10 s 416 kB This is a valuable tool to get an approximate measurement of the memory footprint for a task. Cc: Hugh Dickins <hugh@veritas.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Christoph Lameter <clameter@sgi.com> Signed-off-by: David Rientjes <rientjes@google.com> [akpm@linux-foundation.org: build fixes] [mpm@selenic.com: rename for_each_pmd] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Rientjes
Linus Torvalds
parent
f79f177c25
commit
b813e931b4
4 changed files with 116 additions and 31 deletions
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@ -122,21 +122,22 @@ subdirectory has the entries listed in Table 1-1.
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Table 1-1: Process specific entries in /proc
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..............................................................................
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File Content
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cmdline Command line arguments
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cpu Current and last cpu in which it was executed (2.4)(smp)
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cwd Link to the current working directory
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environ Values of environment variables
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exe Link to the executable of this process
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fd Directory, which contains all file descriptors
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maps Memory maps to executables and library files (2.4)
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mem Memory held by this process
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root Link to the root directory of this process
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stat Process status
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statm Process memory status information
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status Process status in human readable form
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wchan If CONFIG_KALLSYMS is set, a pre-decoded wchan
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smaps Extension based on maps, presenting the rss size for each mapped file
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File Content
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clear_refs Clears page referenced bits shown in smaps output
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cmdline Command line arguments
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cpu Current and last cpu in which it was executed (2.4)(smp)
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cwd Link to the current working directory
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environ Values of environment variables
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exe Link to the executable of this process
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fd Directory, which contains all file descriptors
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maps Memory maps to executables and library files (2.4)
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mem Memory held by this process
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root Link to the root directory of this process
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stat Process status
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statm Process memory status information
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status Process status in human readable form
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wchan If CONFIG_KALLSYMS is set, a pre-decoded wchan
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smaps Extension based on maps, the rss size for each mapped file
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..............................................................................
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For example, to get the status information of a process, all you have to do is
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@ -715,6 +715,40 @@ static const struct file_operations proc_oom_adjust_operations = {
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.write = oom_adjust_write,
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};
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static ssize_t clear_refs_write(struct file *file, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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struct task_struct *task;
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char buffer[PROC_NUMBUF], *end;
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struct mm_struct *mm;
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memset(buffer, 0, sizeof(buffer));
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if (count > sizeof(buffer) - 1)
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count = sizeof(buffer) - 1;
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if (copy_from_user(buffer, buf, count))
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return -EFAULT;
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if (!simple_strtol(buffer, &end, 0))
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return -EINVAL;
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if (*end == '\n')
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end++;
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task = get_proc_task(file->f_path.dentry->d_inode);
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if (!task)
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return -ESRCH;
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mm = get_task_mm(task);
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if (mm) {
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clear_refs_smap(mm);
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mmput(mm);
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}
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put_task_struct(task);
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if (end - buffer == 0)
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return -EIO;
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return end - buffer;
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}
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static struct file_operations proc_clear_refs_operations = {
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.write = clear_refs_write,
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};
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#ifdef CONFIG_AUDITSYSCALL
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#define TMPBUFLEN 21
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static ssize_t proc_loginuid_read(struct file * file, char __user * buf,
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@ -1851,6 +1885,7 @@ static struct pid_entry tgid_base_stuff[] = {
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REG("mounts", S_IRUGO, mounts),
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REG("mountstats", S_IRUSR, mountstats),
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#ifdef CONFIG_MMU
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REG("clear_refs", S_IWUSR, clear_refs),
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REG("smaps", S_IRUGO, smaps),
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#endif
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#ifdef CONFIG_SECURITY
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@ -2132,6 +2167,7 @@ static struct pid_entry tid_base_stuff[] = {
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LNK("exe", exe),
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REG("mounts", S_IRUGO, mounts),
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#ifdef CONFIG_MMU
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REG("clear_refs", S_IWUSR, clear_refs),
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REG("smaps", S_IRUGO, smaps),
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#endif
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#ifdef CONFIG_SECURITY
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@ -195,7 +195,7 @@ static int show_map_internal(struct seq_file *m, void *v, struct mem_size_stats
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"Shared_Dirty: %8lu kB\n"
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"Private_Clean: %8lu kB\n"
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"Private_Dirty: %8lu kB\n"
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"Pgs_Referenced: %8lu kB\n",
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"Referenced: %8lu kB\n",
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(vma->vm_end - vma->vm_start) >> 10,
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mss->resident >> 10,
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mss->shared_clean >> 10,
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@ -214,9 +214,9 @@ static int show_map(struct seq_file *m, void *v)
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return show_map_internal(m, v, NULL);
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}
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static void smaps_one_pmd(struct vm_area_struct *vma, pmd_t *pmd,
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unsigned long addr, unsigned long end,
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void *private)
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static void smaps_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
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unsigned long addr, unsigned long end,
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void *private)
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{
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struct mem_size_stats *mss = private;
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pte_t *pte, ptent;
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@ -254,8 +254,34 @@ static void smaps_one_pmd(struct vm_area_struct *vma, pmd_t *pmd,
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cond_resched();
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}
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static inline void for_each_pmd_in_pud(struct pmd_walker *walker, pud_t *pud,
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unsigned long addr, unsigned long end)
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static void clear_refs_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
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unsigned long addr, unsigned long end,
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void *private)
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{
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pte_t *pte, ptent;
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spinlock_t *ptl;
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struct page *page;
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pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
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for (; addr != end; pte++, addr += PAGE_SIZE) {
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ptent = *pte;
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if (!pte_present(ptent))
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continue;
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page = vm_normal_page(vma, addr, ptent);
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if (!page)
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continue;
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/* Clear accessed and referenced bits. */
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ptep_test_and_clear_young(vma, addr, pte);
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ClearPageReferenced(page);
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}
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pte_unmap_unlock(pte - 1, ptl);
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cond_resched();
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}
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static inline void walk_pmd_range(struct pmd_walker *walker, pud_t *pud,
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unsigned long addr, unsigned long end)
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{
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pmd_t *pmd;
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unsigned long next;
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@ -269,8 +295,8 @@ static inline void for_each_pmd_in_pud(struct pmd_walker *walker, pud_t *pud,
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}
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}
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static inline void for_each_pud_in_pgd(struct pmd_walker *walker, pgd_t *pgd,
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unsigned long addr, unsigned long end)
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static inline void walk_pud_range(struct pmd_walker *walker, pgd_t *pgd,
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unsigned long addr, unsigned long end)
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{
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pud_t *pud;
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unsigned long next;
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@ -280,15 +306,24 @@ static inline void for_each_pud_in_pgd(struct pmd_walker *walker, pgd_t *pgd,
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next = pud_addr_end(addr, end);
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if (pud_none_or_clear_bad(pud))
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continue;
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for_each_pmd_in_pud(walker, pud, addr, next);
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walk_pmd_range(walker, pud, addr, next);
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}
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}
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static inline void for_each_pmd(struct vm_area_struct *vma,
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void (*action)(struct vm_area_struct *, pmd_t *,
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unsigned long, unsigned long,
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void *),
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void *private)
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/*
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* walk_page_range - walk the page tables of a VMA with a callback
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* @vma - VMA to walk
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* @action - callback invoked for every bottom-level (PTE) page table
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* @private - private data passed to the callback function
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*
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* Recursively walk the page table for the memory area in a VMA, calling
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* a callback for every bottom-level (PTE) page table.
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*/
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static inline void walk_page_range(struct vm_area_struct *vma,
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void (*action)(struct vm_area_struct *,
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pmd_t *, unsigned long,
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unsigned long, void *),
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void *private)
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{
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unsigned long addr = vma->vm_start;
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unsigned long end = vma->vm_end;
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@ -305,7 +340,7 @@ static inline void for_each_pmd(struct vm_area_struct *vma,
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next = pgd_addr_end(addr, end);
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if (pgd_none_or_clear_bad(pgd))
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continue;
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for_each_pud_in_pgd(&walker, pgd, addr, next);
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walk_pud_range(&walker, pgd, addr, next);
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}
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}
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@ -316,10 +351,22 @@ static int show_smap(struct seq_file *m, void *v)
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memset(&mss, 0, sizeof mss);
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if (vma->vm_mm && !is_vm_hugetlb_page(vma))
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for_each_pmd(vma, smaps_one_pmd, &mss);
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walk_page_range(vma, smaps_pte_range, &mss);
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return show_map_internal(m, v, &mss);
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}
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void clear_refs_smap(struct mm_struct *mm)
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{
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struct vm_area_struct *vma;
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down_read(&mm->mmap_sem);
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for (vma = mm->mmap; vma; vma = vma->vm_next)
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if (vma->vm_mm && !is_vm_hugetlb_page(vma))
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walk_page_range(vma, clear_refs_pte_range, NULL);
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flush_tlb_mm(mm);
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up_read(&mm->mmap_sem);
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}
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static void *m_start(struct seq_file *m, loff_t *pos)
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{
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struct proc_maps_private *priv = m->private;
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@ -104,6 +104,7 @@ int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir);
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unsigned long task_vsize(struct mm_struct *);
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int task_statm(struct mm_struct *, int *, int *, int *, int *);
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char *task_mem(struct mm_struct *, char *);
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void clear_refs_smap(struct mm_struct *mm);
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extern struct proc_dir_entry *create_proc_entry(const char *name, mode_t mode,
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struct proc_dir_entry *parent);
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