Messages in this thread Patch in this message |  | | Date | Tue, 6 Feb 2007 22:15:59 -0800 (PST) | From | David Rientjes <> | Subject | [patch 3/3 take2] smaps: add clear_refs file to clear reference |
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Adds an additional file to /proc/pid: clear_refs. When any non-zero number is written to this file, all the PG_referenced flags and PAGE_ACCESSED (meaning the page has been accessed) are cleared within each VMA for the corresponding task.
It is now possible to measure 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 time interval later.
The /proc/pid/clear_refs file is only writable by the user who owns the 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> --- fs/proc/base.c | 31 +++++++++++++++++++++++++++++++ fs/proc/task_mmu.c | 37 +++++++++++++++++++++++++++++++++++++ include/linux/proc_fs.h | 1 + 3 files changed, 69 insertions(+), 0 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c index 1a979ea..b50315f 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -715,6 +715,35 @@ static struct file_operations proc_oom_adjust_operations = { .write = oom_adjust_write, }; +static ssize_t clear_refs_write(struct file *file, const char __user *buf, + size_t count, loff_t *ppos) +{ + struct task_struct *task; + char buffer[PROC_NUMBUF], *end; + + memset(buffer, 0, sizeof(buffer)); + if (count > sizeof(buffer) - 1) + count = sizeof(buffer) - 1; + if (copy_from_user(buffer, buf, count)) + return -EFAULT; + if (!simple_strtol(buffer, &end, 0)) + return -EINVAL; + if (*end == '\n') + end++; + task = get_proc_task(file->f_path.dentry->d_inode); + if (!task) + return -ESRCH; + clear_refs_smap(task->mm->mmap); + put_task_struct(task); + if (end - buffer == 0) + return -EIO; + return end - buffer; +} + +static struct file_operations proc_clear_refs_operations = { + .write = clear_refs_write, +}; + #ifdef CONFIG_AUDITSYSCALL #define TMPBUFLEN 21 static ssize_t proc_loginuid_read(struct file * file, char __user * buf, @@ -1856,6 +1885,7 @@ static struct pid_entry tgid_base_stuff[] = { REG("mounts", S_IRUGO, mounts), REG("mountstats", S_IRUSR, mountstats), #ifdef CONFIG_MMU + REG("clear_refs", S_IWUSR, clear_refs), REG("smaps", S_IRUGO, smaps), #endif #ifdef CONFIG_SECURITY @@ -2137,6 +2167,7 @@ static struct pid_entry tid_base_stuff[] = { LNK("exe", exe), REG("mounts", S_IRUGO, mounts), #ifdef CONFIG_MMU + REG("clear_refs", S_IWUSR, clear_refs), REG("smaps", S_IRUGO, smaps), #endif #ifdef CONFIG_SECURITY diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 50bd004..b689a92 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -322,6 +322,27 @@ static void smaps_pte_func(struct pte_walker *walker, pte_t *pte, } /* + * Called for each PTE in the struct pte_walker address range. For all normal, + * present pages, we clear their referenced bits. + */ +static void clear_refs_pte_func(struct pte_walker *walker, pte_t *pte, + unsigned long addr) +{ + struct page *page; + pte_t ptent; + + ptent = *pte; + if (!pte_present(ptent)) + return; + + page = vm_normal_page(walker->vma, addr, ptent); + if (!page) + return; + pte_mkold(ptent); + ClearPageReferenced(page); +} + +/* * Displays the smap for the process. smaps_pte_func() is called for each PTE * in the range from vma->vm_start to vma->vm_end. */ @@ -343,6 +364,22 @@ static int show_smap(struct seq_file *m, void *v) return show_map_internal(m, v, &mss); } +void clear_refs_smap(struct vm_area_struct *vma) +{ + for (; vma; vma = vma->vm_next) { + struct pte_walker walker = { + .vma = vma, + .start = vma->vm_start, + .end = vma->vm_end, + .private = NULL, + .func = clear_refs_pte_func, + }; + + if (vma->vm_mm && !is_vm_hugetlb_page(vma)) + walk_pgds(&walker); + }; +} + static void *m_start(struct seq_file *m, loff_t *pos) { struct proc_maps_private *priv = m->private; diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h index 87dec8f..f3d426b 100644 --- a/include/linux/proc_fs.h +++ b/include/linux/proc_fs.h @@ -104,6 +104,7 @@ int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir); unsigned long task_vsize(struct mm_struct *); int task_statm(struct mm_struct *, int *, int *, int *, int *); char *task_mem(struct mm_struct *, char *); +void clear_refs_smap(struct vm_area_struct *); extern struct proc_dir_entry *create_proc_entry(const char *name, mode_t mode, struct proc_dir_entry *parent); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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