mm: vmstat.c: make extfrag_index show more pretty

fragmentation_index may return -1000 and the corresponding formated
value showed by seq_printf will take a negative signatrue, but other
positive formated values don't take a positive signatrue, so the output
becomes unaligned.

before:
  Node 0, zone      DMA -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000
  Node 0, zone    DMA32 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000
  Node 0, zone   Normal -1.000 -1.000 -1.000 -1.000 0.931 0.966 0.983 0.992 0.996 0.998 0.999

after this patch:
  Node 0, zone      DMA -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000
  Node 0, zone    DMA32 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000
  Node 0, zone   Normal -1.000 -1.000 -1.000 -1.000  0.931  0.966  0.983  0.992  0.996  0.998  0.999

Link: https://lkml.kernel.org/r/20211019103241.134797-1-linf@wangsu.com
Signed-off-by: Lin Feng <linf@wangsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/vmstat.c b/mm/vmstat.c
index 0fde7470368df77c19e5e0eca472916f40d33775..d701c335628c86c799bb33c7dba2f42f1c7b6fed 100644 (file)
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -2191,7 +2191,7 @@ static void extfrag_show_print(struct seq_file *m,
        for (order = 0; order < MAX_ORDER; ++order) {
                fill_contig_page_info(zone, order, &info);
                index = __fragmentation_index(order, &info);
-               seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
+               seq_printf(m, "%2d.%03d ", index / 1000, index % 1000);
        }
 
        seq_putc(m, '\n');