linux-kernel - [PATCH 1/2] scripts/bloat-o-meter: don't use readlines()

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Message-ID: <20161119004143.GA1200@avx2>
Date:   Sat, 19 Nov 2016 03:41:43 +0300
From:   Alexey Dobriyan <adobriyan@...il.com>
To:     akpm@...ux-foundation.org
Cc:     linux-kernel@...r.kernel.org, mpm@...enic.com
Subject: [PATCH 1/2] scripts/bloat-o-meter: don't use readlines()

readlines() conses whole list before doing anything which is slower
for big object files. Use per line iterator.

Speed up is ~2% on "allyesconfig" type of kernel.

	$ perf stat -r 16 taskset -c 15 ./scripts/bloat-o-meter ../vmlinux-000 ../obj/vmlinux >/dev/null
		...
Before:	7.247708646 seconds time elapsed                                          ( +-  0.28% )
After:	7.091202853 seconds time elapsed                                          ( +-  0.15% )


Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
---

 scripts/bloat-o-meter |   23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

--- a/scripts/bloat-o-meter
+++ b/scripts/bloat-o-meter
@@ -18,17 +18,18 @@ if len(sys.argv) != 3:
 
 def getsizes(file):
     sym = {}
-    for l in os.popen("nm --size-sort " + file).readlines():
-        size, type, name = l[:-1].split()
-        if type in "tTdDbBrR":
-            # strip generated symbols
-            if name.startswith("__mod_"): continue
-            if name.startswith("SyS_"): continue
-            if name.startswith("compat_SyS_"): continue
-            if name == "linux_banner": continue
-            # statics and some other optimizations adds random .NUMBER
-            name = re.sub(r'\.[0-9]+', '', name)
-            sym[name] = sym.get(name, 0) + int(size, 16)
+    with os.popen("nm --size-sort " + file) as f:
+        for line in f:
+            size, type, name = line.split()
+            if type in "tTdDbBrR":
+                # strip generated symbols
+                if name.startswith("__mod_"): continue
+                if name.startswith("SyS_"): continue
+                if name.startswith("compat_SyS_"): continue
+                if name == "linux_banner": continue
+                # statics and some other optimizations adds random .NUMBER
+                name = re.sub(r'\.[0-9]+', '', name)
+                sym[name] = sym.get(name, 0) + int(size, 16)
     return sym
 
 old = getsizes(sys.argv[1])