page-types: exit early when invoked with -d|--describe
Alex Chiang [Tue, 15 Dec 2009 01:57:54 +0000 (17:57 -0800)]
On a system with large amount of memory (256GB), invoking page-types can
take quite a long time, which is unreasonable considering the user only
wants a description of the flags:

# time ./page-types -d 0x10
0x0000000000000010 ____D_____________________________ dirty

real 0m34.285s
user 0m1.966s
sys 0m32.313s

This is because we still walk the entire address range.

Exiting early seems like a reasonble solution:

# time ./page-types -d 0x10
0x0000000000000010 ____D_____________________________ dirty

real 0m0.007s
user 0m0.001s
sys 0m0.005s

Signed-off-by: Alex Chiang <achiang@hp.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Haicheng Li <haicheng.li@intel.com>
Acked-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/vm/page-types.c

index 19ca23c..7a7d9ba 100644 (file)
@@ -940,9 +940,8 @@ int main(int argc, char *argv[])
                        parse_bits_mask(optarg);
                        break;
                case 'd':
-                       opt_no_summary = 1;
                        describe_flags(optarg);
-                       break;
+                       exit(0);
                case 'l':
                        opt_list = 1;
                        break;