Add the "last_addr" optimization back. Like before, every ->show() method checks !seq_overflow() and sets m->version = vma->vm_start.
However, it also checks that m_next_vma(vma) != NULL, otherwise it sets m->version = -1 for the lockless "EOF" fast-path in m_start(). m_start() can simply do find_vma() + m_next_vma() if last_addr is not zero, the code looks clear and simple and this case is clearly separated from "scan vmas" path. Signed-off-by: Oleg Nesterov <[email protected]> --- fs/proc/task_mmu.c | 21 +++++++++++++++++++++ 1 files changed, 21 insertions(+), 0 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 2ba3b16..1b897dc 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -145,13 +145,24 @@ m_next_vma(struct proc_maps_private *priv, struct vm_area_struct *vma) return vma->vm_next ?: priv->tail_vma; } +static void m_cache_vma(struct seq_file *m, struct vm_area_struct *vma) +{ + if (m->count < m->size) /* vma is copied successfully */ + m->version = m_next_vma(m->private, vma) ? vma->vm_start : -1UL; +} + static void *m_start(struct seq_file *m, loff_t *ppos) { struct proc_maps_private *priv = m->private; + unsigned long last_addr = m->version; struct mm_struct *mm; struct vm_area_struct *vma; unsigned int pos = *ppos; + /* See m_cache_vma(). Zero at the start or after lseek. */ + if (last_addr == -1UL) + return NULL; + priv->task = get_pid_task(priv->pid, PIDTYPE_PID); if (!priv->task) return ERR_PTR(-ESRCH); @@ -164,6 +175,13 @@ static void *m_start(struct seq_file *m, loff_t *ppos) hold_task_mempolicy(priv); priv->tail_vma = get_gate_vma(mm); + if (last_addr) { + vma = find_vma(mm, last_addr); + if (vma && (vma = m_next_vma(priv, vma))) + return vma; + } + + m->version = 0; if (pos < mm->map_count) { for (vma = mm->mmap; pos; pos--) vma = vma->vm_next; @@ -339,6 +357,7 @@ done: static int show_map(struct seq_file *m, void *v, int is_pid) { show_map_vma(m, v, is_pid); + m_cache_vma(m, v); return 0; } @@ -616,6 +635,7 @@ static int show_smap(struct seq_file *m, void *v, int is_pid) mss.nonlinear >> 10); show_smap_vma_flags(m, vma); + m_cache_vma(m, vma); return 0; } @@ -1446,6 +1466,7 @@ static int show_numa_map(struct seq_file *m, void *v, int is_pid) seq_printf(m, " N%d=%lu", nid, md->node[nid]); out: seq_putc(m, '\n'); + m_cache_vma(m, vma); return 0; } -- 1.5.5.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
