commit 77cb3738174ea8789494ccf65250db994e50be8c
parent f80cf63ee3b542d133d0860b7ccf790719441d18
Author: Remy Noulin <loader2x@gmail.com>
Date: Thu, 4 Jan 2018 22:04:57 +0100
add malloc.c
.gitignore | 3 ++
README.md | 130 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
malloc.c | 31 +++++++++++++++
3 files changed, 164 insertions(+)
Diffstat:
| M | .gitignore | | | 3 | +++ |
| A | README.md | | | 130 | +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
| A | malloc.c | | | 31 | +++++++++++++++++++++++++++++++ |
3 files changed, 164 insertions(+), 0 deletions(-)
diff --git a/.gitignore b/.gitignore
@@ -1,3 +1,6 @@
+malloc
+*.swp
+
# Prerequisites
*.d
diff --git a/README.md b/README.md
@@ -0,0 +1,130 @@
+malloc.c is a program allocating blocks of memory with malloc.
+
+strace logs the system calls to the linux kernel, __mmap__ is the syscall used by malloc to allocate large blocks of RAM.
+
+The time spend in each malloc is measured, as you can see in the log, there is only a small variation.
+
+malloc.c allocates buffers increasingly big starting with 1KB and ending with 32MB.
+
+On my system, glibc allocates 128KB initially, so the first 6 allocations dont trigger a syscall.
+
+For buffers larger than 128KB, malloc calls the mmap syscall and the time spent in malloc is on average the same.
+
+When allocating buffers with alloca, the time spent in alloca depends on the buffer size, it takes more time for larger buffers. alloca never triggers a syscall as seen in the strace log.
+
+Compiling and running:
+
+```
+sheepy -c malloc.c
+./malloc
+strace ./malloc
+```
+
+malloc output:
+```
+alloc
+0 0x55949cb3a420 size: 1KB, time: 560ns
+1 0x55949cb3a830 size: 2KB, time: 1612ns
+2 0x55949cb3b040 size: 4KB, time: 1568ns
+3 0x55949cb3c050 size: 8KB, time: 1303ns
+4 0x55949cb3e060 size: 16KB, time: 1211ns
+5 0x55949cb42070 size: 32KB, time: 1206ns
+6 0x55949cb4a080 size: 64KB, time: 1217ns
+7 0x7f6f87048010 size: 128KB, time: 2899ns
+8 0x7f6f87007010 size: 256KB, time: 2574ns
+9 0x7f6f86f86010 size: 512KB, time: 1868ns
+10 0x7f6f867a8010 size: 1024KB, time: 2894ns
+11 0x7f6f865a7010 size: 2048KB, time: 2189ns
+12 0x7f6f861a6010 size: 4096KB, time: 2329ns
+13 0x7f6f859a5010 size: 8192KB, time: 2323ns
+14 0x7f6f849a4010 size: 16384KB, time: 1973ns
+15 0x7f6f829a3010 size: 32768KB, time: 2191ns
+s
+alloca 0 0x7fff5b02ce70 size: 1KB, time: 39ns
+alloca 1 0x7fff5b02c660 size: 2KB, time: 32ns
+alloca 2 0x7fff5b02b650 size: 4KB, time: 31ns
+alloca 3 0x7fff5b029640 size: 8KB, time: 1078ns
+alloca 4 0x7fff5b025630 size: 16KB, time: 970ns
+alloca 5 0x7fff5b01d620 size: 32KB, time: 1162ns
+alloca 6 0x7fff5b00d610 size: 64KB, time: 978ns
+alloca 7 0x7fff5afed600 size: 128KB, time: 1425ns
+alloca 8 0x7fff5afad5f0 size: 256KB, time: 1044ns
+alloca 9 0x7fff5af2d5e0 size: 512KB, time: 1148ns
+alloca 10 0x7fff5ae2d5d0 size: 1024KB, time: 961ns
+alloca 11 0x7fff5ac2d5c0 size: 2048KB, time: 1241ns
+```
+
+strace log on debian stretch:
+
+```
+write(1, "alloc\n", 6alloc
+) = 6
+write(1, "0 0x55e346706420 size: 1024, tim"..., 410 0x55e346706420 size: 1024, time: 837ns
+) = 41
+write(1, "1 0x55e346706830 size: 2048, tim"..., 421 0x55e346706830 size: 2048, time: 1960ns
+) = 42
+write(1, "2 0x55e346707040 size: 4096, tim"..., 422 0x55e346707040 size: 4096, time: 1712ns
+) = 42
+write(1, "3 0x55e346708050 size: 8192, tim"..., 423 0x55e346708050 size: 8192, time: 1588ns
+) = 42
+write(1, "4 0x55e34670a060 size: 16384, ti"..., 434 0x55e34670a060 size: 16384, time: 1573ns
+) = 43
+write(1, "5 0x55e34670e070 size: 32768, ti"..., 435 0x55e34670e070 size: 32768, time: 1486ns
+) = 43
+write(1, "6 0x55e346716080 size: 65536, ti"..., 436 0x55e346716080 size: 65536, time: 1487ns
+) = 43
+mmap(NULL, 135168, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f475dc2f000
+write(1, "7 0x7f475dc2f010 size: 131072, t"..., 457 0x7f475dc2f010 size: 131072, time: 20558ns
+) = 45
+mmap(NULL, 266240, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f475dbee000
+write(1, "8 0x7f475dbee010 size: 262144, t"..., 458 0x7f475dbee010 size: 262144, time: 19708ns
+) = 45
+mmap(NULL, 528384, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f475db6d000
+write(1, "9 0x7f475db6d010 size: 524288, t"..., 459 0x7f475db6d010 size: 524288, time: 16711ns
+) = 45
+mmap(NULL, 1052672, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f475d38f000
+write(1, "10 0x7f475d38f010 size: 1048576,"..., 4710 0x7f475d38f010 size: 1048576, time: 19502ns
+) = 47
+mmap(NULL, 2101248, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f475d18e000
+write(1, "11 0x7f475d18e010 size: 2097152,"..., 4711 0x7f475d18e010 size: 2097152, time: 18659ns
+) = 47
+mmap(NULL, 4198400, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f475cd8d000
+write(1, "12 0x7f475cd8d010 size: 4194304,"..., 4712 0x7f475cd8d010 size: 4194304, time: 17346ns
+) = 47
+mmap(NULL, 8392704, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f475c58c000
+write(1, "13 0x7f475c58c010 size: 8388608,"..., 4713 0x7f475c58c010 size: 8388608, time: 18613ns
+) = 47
+mmap(NULL, 16781312, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f475b58b000
+write(1, "14 0x7f475b58b010 size: 16777216"..., 4814 0x7f475b58b010 size: 16777216, time: 17792ns
+) = 48
+mmap(NULL, 33558528, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f475958a000
+write(1, "15 0x7f475958a010 size: 33554432"..., 4815 0x7f475958a010 size: 33554432, time: 16998ns
+) = 48
+write(1, "s\n", 2s
+) = 2
+write(1, "alloca 0 0x7ffd31053480 size: 1K"..., 46alloca 0 0x7ffd31053480 size: 1KB, time: 51ns
+) = 46
+write(1, "alloca 1 0x7ffd31052c70 size: 2K"..., 46alloca 1 0x7ffd31052c70 size: 2KB, time: 37ns
+) = 46
+write(1, "alloca 2 0x7ffd31051c60 size: 4K"..., 46alloca 2 0x7ffd31051c60 size: 4KB, time: 60ns
+) = 46
+write(1, "alloca 3 0x7ffd3104fc50 size: 8K"..., 48alloca 3 0x7ffd3104fc50 size: 8KB, time: 1897ns
+) = 48
+write(1, "alloca 4 0x7ffd3104bc40 size: 16"..., 49alloca 4 0x7ffd3104bc40 size: 16KB, time: 1224ns
+) = 49
+write(1, "alloca 5 0x7ffd31043c30 size: 32"..., 49alloca 5 0x7ffd31043c30 size: 32KB, time: 1266ns
+) = 49
+write(1, "alloca 6 0x7ffd31033c20 size: 64"..., 49alloca 6 0x7ffd31033c20 size: 64KB, time: 1318ns
+) = 49
+write(1, "alloca 7 0x7ffd31013c10 size: 12"..., 50alloca 7 0x7ffd31013c10 size: 128KB, time: 1908ns
+) = 50
+write(1, "alloca 8 0x7ffd30fd3c00 size: 25"..., 50alloca 8 0x7ffd30fd3c00 size: 256KB, time: 2673ns
+) = 50
+write(1, "alloca 9 0x7ffd30f53bf0 size: 51"..., 50alloca 9 0x7ffd30f53bf0 size: 512KB, time: 2582ns
+) = 50
+write(1, "alloca 10 0x7ffd30e53be0 size: 1"..., 52alloca 10 0x7ffd30e53be0 size: 1024KB, time: 1391ns
+) = 52
+write(1, "alloca 11 0x7ffd30c53bd0 size: 2"..., 52alloca 11 0x7ffd30c53bd0 size: 2048KB, time: 2118ns
+) = 52
+exit_group(0) = ?
+```
diff --git a/malloc.c b/malloc.c
@@ -0,0 +1,31 @@
+#! /usr/bin/env sheepy
+
+#include "libsheepyObject.h"
+
+int argc; char **argv;
+
+int main(int ARGC, char** ARGV) {
+
+ argc = ARGC; argv = ARGV;
+
+ puts("alloc");
+ char *s;
+ u64 start, end;
+ range(i, 16) {
+ start = getMonotonicTime();
+ s = malloc((1<<i)*1024);
+ end = getMonotonicTime();
+ printf("%d %p size: %ldKB, time: %ldns\n", (int)i ,s, 1<<i, end-start);
+ }
+
+ s[0] = 's';
+ s[1] = 0;
+ puts(s);
+
+ range(i, 12) {
+ start = getMonotonicTime();
+ s = alloca((1<<i)*1024);
+ end = getMonotonicTime();
+ printf("alloca %d %p size: %ldKB, time: %ldns\n", (int)i ,s, 1<<i, end-start);
+ }
+}
