From 1306d603fcf1f6682f8575d1ff23631a24184b21 Mon Sep 17 00:00:00 2001 From: KOSAKI Motohiro Date: Fri, 8 Jan 2010 14:42:56 -0800 Subject: [PATCH] proc: partially revert "procfs: provide stack information for threads" Commit d899bf7b (procfs: provide stack information for threads) introduced to show stack information in /proc/{pid}/status. But it cause large performance regression. Unfortunately /proc/{pid}/status is used ps command too and ps is one of most important component. Because both to take mmap_sem and page table walk are heavily operation. If many process run, the ps performance is, [before d899bf7b] % perf stat ps >/dev/null Performance counter stats for 'ps': 4090.435806 task-clock-msecs # 0.032 CPUs 229 context-switches # 0.000 M/sec 0 CPU-migrations # 0.000 M/sec 234 page-faults # 0.000 M/sec 8587565207 cycles # 2099.425 M/sec 9866662403 instructions # 1.149 IPC 3789415411 cache-references # 926.409 M/sec 30419509 cache-misses # 7.437 M/sec 128.859521955 seconds time elapsed [after d899bf7b] % perf stat ps > /dev/null Performance counter stats for 'ps': 4305.081146 task-clock-msecs # 0.028 CPUs 480 context-switches # 0.000 M/sec 2 CPU-migrations # 0.000 M/sec 237 page-faults # 0.000 M/sec 9021211334 cycles # 2095.480 M/sec 10605887536 instructions # 1.176 IPC 3612650999 cache-references # 839.160 M/sec 23917502 cache-misses # 5.556 M/sec 152.277819582 seconds time elapsed Thus, this patch revert it. Fortunately /proc/{pid}/task/{tid}/smaps provide almost same information. we can use it. Commit d899bf7b introduced two features: 1) Add the annotattion of [thread stack: xxxx] mark to /proc/{pid}/task/{tid}/maps. 2) Add StackUsage field to /proc/{pid}/status. I only revert (2), because I haven't seen (1) cause regression. Signed-off-by: KOSAKI Motohiro Cc: Stefani Seibold Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Alexey Dobriyan Cc: "Eric W. Biederman" Cc: Randy Dunlap Cc: Andrew Morton Cc: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/filesystems/proc.txt | 2 - fs/proc/array.c | 89 ------------------------------ 2 files changed, 91 deletions(-) diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index 220cc6376ef8..0d07513a67a6 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -177,7 +177,6 @@ read the file /proc/PID/status: CapBnd: ffffffffffffffff voluntary_ctxt_switches: 0 nonvoluntary_ctxt_switches: 1 - Stack usage: 12 kB This shows you nearly the same information you would get if you viewed it with the ps command. In fact, ps uses the proc file system to obtain its @@ -231,7 +230,6 @@ Table 1-2: Contents of the statm files (as of 2.6.30-rc7) Mems_allowed_list Same as previous, but in "list format" voluntary_ctxt_switches number of voluntary context switches nonvoluntary_ctxt_switches number of non voluntary context switches - Stack usage: stack usage high water mark (round up to page size) .............................................................................. Table 1-3: Contents of the statm files (as of 2.6.8-rc3) diff --git a/fs/proc/array.c b/fs/proc/array.c index f560325c444f..13b5d0708175 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -327,94 +327,6 @@ static inline void task_context_switch_counts(struct seq_file *m, p->nivcsw); } -#ifdef CONFIG_MMU - -struct stack_stats { - struct vm_area_struct *vma; - unsigned long startpage; - unsigned long usage; -}; - -static int stack_usage_pte_range(pmd_t *pmd, unsigned long addr, - unsigned long end, struct mm_walk *walk) -{ - struct stack_stats *ss = walk->private; - struct vm_area_struct *vma = ss->vma; - pte_t *pte, ptent; - spinlock_t *ptl; - int ret = 0; - - pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); - for (; addr != end; pte++, addr += PAGE_SIZE) { - ptent = *pte; - -#ifdef CONFIG_STACK_GROWSUP - if (pte_present(ptent) || is_swap_pte(ptent)) - ss->usage = addr - ss->startpage + PAGE_SIZE; -#else - if (pte_present(ptent) || is_swap_pte(ptent)) { - ss->usage = ss->startpage - addr + PAGE_SIZE; - pte++; - ret = 1; - break; - } -#endif - } - pte_unmap_unlock(pte - 1, ptl); - cond_resched(); - return ret; -} - -static inline unsigned long get_stack_usage_in_bytes(struct vm_area_struct *vma, - struct task_struct *task) -{ - struct stack_stats ss; - struct mm_walk stack_walk = { - .pmd_entry = stack_usage_pte_range, - .mm = vma->vm_mm, - .private = &ss, - }; - - if (!vma->vm_mm || is_vm_hugetlb_page(vma)) - return 0; - - ss.vma = vma; - ss.startpage = task->stack_start & PAGE_MASK; - ss.usage = 0; - -#ifdef CONFIG_STACK_GROWSUP - walk_page_range(KSTK_ESP(task) & PAGE_MASK, vma->vm_end, - &stack_walk); -#else - walk_page_range(vma->vm_start, (KSTK_ESP(task) & PAGE_MASK) + PAGE_SIZE, - &stack_walk); -#endif - return ss.usage; -} - -static inline void task_show_stack_usage(struct seq_file *m, - struct task_struct *task) -{ - struct vm_area_struct *vma; - struct mm_struct *mm = get_task_mm(task); - - if (mm) { - down_read(&mm->mmap_sem); - vma = find_vma(mm, task->stack_start); - if (vma) - seq_printf(m, "Stack usage:\t%lu kB\n", - get_stack_usage_in_bytes(vma, task) >> 10); - - up_read(&mm->mmap_sem); - mmput(mm); - } -} -#else -static void task_show_stack_usage(struct seq_file *m, struct task_struct *task) -{ -} -#endif /* CONFIG_MMU */ - static void task_cpus_allowed(struct seq_file *m, struct task_struct *task) { seq_printf(m, "Cpus_allowed:\t"); @@ -445,7 +357,6 @@ int proc_pid_status(struct seq_file *m, struct pid_namespace *ns, task_show_regs(m, task); #endif task_context_switch_counts(m, task); - task_show_stack_usage(m, task); return 0; } -- 2.30.2