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Subject[PATCH 2/2] proc: task_mmu: Reduce output processing cpu time
Date
Use the new __seq_open_private_buffer to estimate the final
output /proc/<pid>/smaps filesize to reduce the number of
reallocations of overflowed buffers.

Use a simpler single-line function to emit various values in kB.

Signed-off-by: Joe Perches <joe@perches.com>
---
fs/proc/task_mmu.c | 94 ++++++++++++++++++++++++++++--------------------------
1 file changed, 48 insertions(+), 46 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 187d84e..170509b 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -224,19 +224,21 @@ static void m_stop(struct seq_file *m, void *v)
static int proc_maps_open(struct inode *inode, struct file *file,
const struct seq_operations *ops, int psize)
{
- struct proc_maps_private *priv = __seq_open_private(file, ops, psize);
+ struct proc_maps_private *priv;
+ struct mm_struct *mm;
+
+ mm = proc_mem_open(inode, PTRACE_MODE_READ);
+ if (IS_ERR(mm))
+ return PTR_ERR(mm);

+ priv = __seq_open_private_bufsize(file, ops, psize,
+ mm && mm->map_count ?
+ mm->map_count * 0x300 : PAGE_SIZE);
if (!priv)
return -ENOMEM;

priv->inode = inode;
- priv->mm = proc_mem_open(inode, PTRACE_MODE_READ);
- if (IS_ERR(priv->mm)) {
- int err = PTR_ERR(priv->mm);
-
- seq_release_private(inode, file);
- return err;
- }
+ priv->mm = mm;

return 0;
}
@@ -721,6 +723,25 @@ void __weak arch_show_smap(struct seq_file *m, struct vm_area_struct *vma)
{
}

+static void show_val_kb(struct seq_file *m, const char *s, unsigned long num)
+{
+ char v[32];
+ static const char blanks[7] = {' ', ' ', ' ', ' ',' ', ' ', ' '};
+ int len;
+
+ len = num_to_str(v, sizeof(v), num >> 10);
+
+ seq_write(m, s, 16);
+
+ if (len > 0) {
+ if (len < 8)
+ seq_write(m, blanks, 8 - len);
+
+ seq_write(m, v, len);
+ }
+ seq_write(m, " kB\n", 4);
+}
+
static int show_smap(struct seq_file *m, void *v, int is_pid)
{
struct vm_area_struct *vma = v;
@@ -765,44 +786,25 @@ static int show_smap(struct seq_file *m, void *v, int is_pid)

show_map_vma(m, vma, is_pid);

- seq_printf(m,
- "Size: %8lu kB\n"
- "Rss: %8lu kB\n"
- "Pss: %8lu kB\n"
- "Shared_Clean: %8lu kB\n"
- "Shared_Dirty: %8lu kB\n"
- "Private_Clean: %8lu kB\n"
- "Private_Dirty: %8lu kB\n"
- "Referenced: %8lu kB\n"
- "Anonymous: %8lu kB\n"
- "AnonHugePages: %8lu kB\n"
- "ShmemPmdMapped: %8lu kB\n"
- "Shared_Hugetlb: %8lu kB\n"
- "Private_Hugetlb: %7lu kB\n"
- "Swap: %8lu kB\n"
- "SwapPss: %8lu kB\n"
- "KernelPageSize: %8lu kB\n"
- "MMUPageSize: %8lu kB\n"
- "Locked: %8lu kB\n",
- (vma->vm_end - vma->vm_start) >> 10,
- mss.resident >> 10,
- (unsigned long)(mss.pss >> (10 + PSS_SHIFT)),
- mss.shared_clean >> 10,
- mss.shared_dirty >> 10,
- mss.private_clean >> 10,
- mss.private_dirty >> 10,
- mss.referenced >> 10,
- mss.anonymous >> 10,
- mss.anonymous_thp >> 10,
- mss.shmem_thp >> 10,
- mss.shared_hugetlb >> 10,
- mss.private_hugetlb >> 10,
- mss.swap >> 10,
- (unsigned long)(mss.swap_pss >> (10 + PSS_SHIFT)),
- vma_kernel_pagesize(vma) >> 10,
- vma_mmu_pagesize(vma) >> 10,
- (vma->vm_flags & VM_LOCKED) ?
- (unsigned long)(mss.pss >> (10 + PSS_SHIFT)) : 0);
+ show_val_kb(m, "Size: ", vma->vm_end - vma->vm_start);
+ show_val_kb(m, "Rss: ", mss.resident);
+ show_val_kb(m, "Pss: ", mss.pss >> PSS_SHIFT);
+ show_val_kb(m, "Shared_Clean: ", mss.shared_clean);
+ show_val_kb(m, "Shared_Dirty: ", mss.shared_dirty);
+ show_val_kb(m, "Private_Clean: ", mss.private_clean);
+ show_val_kb(m, "Private_Dirty: ", mss.private_dirty);
+ show_val_kb(m, "Referenced: ", mss.referenced);
+ show_val_kb(m, "Anonymous: ", mss.anonymous);
+ show_val_kb(m, "AnonHugePages: ", mss.anonymous_thp);
+ show_val_kb(m, "ShmemPmdMapped: ", mss.shmem_thp);
+ show_val_kb(m, "Shared_Hugetlb: ", mss.shared_hugetlb);
+ seq_printf(m, "Private_Hugetlb: %7lu kB\n", mss.private_hugetlb >> 10);
+ show_val_kb(m, "Swap: ", mss.swap);
+ show_val_kb(m, "SwapPss: ", mss.swap_pss >> PSS_SHIFT);
+ show_val_kb(m, "KernelPageSize: ", vma_kernel_pagesize(vma));
+ show_val_kb(m, "MMUPageSize: ", vma_mmu_pagesize(vma));
+ show_val_kb(m, "Locked: ",
+ vma->vm_flags & VM_LOCKED ? mss.pss >> PSS_SHIFT : 0);

arch_show_smap(m, vma);
show_smap_vma_flags(m, vma);
--
2.8.0.rc4.16.g56331f8
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