Features/PowerManagement/scomes/examples

To have equivalent test enviroment - you can use:

  echo 3 > /proc/sys/vm/drop_caches

will drop all disk caches

  cgroups 

can set the size of memory

C OPTIMIZATIONS

gzip

compiled with different compilation flags:

lines with "-" in cells have the same value for all rows

	with -O2 -march=i386 -mtune=i686	with -O1 -march=i386 -mtune=i686	with -O0 -march=i386 -mtune=i686	with -march=i386 -mtune=i686	without anything
Number of syscalls	-	-	5987	-	-
Kernel/Userspace ticks	314/7394 (7708)	327/7601 (7928)	361/11299 (11660)	420/11605 (12025)	374/10972 (11346)
Read/Written bytes	-	-	152595016	-	-
Pooling syscalls	0	1	0	0	0

tar:

shows too big changes so not good for any statistic :( (no complicated algorithm there)

octave:

startup of octave package:

	with -O2	with -O1	with -O0	without anything
Number of syscalls	13589	?	?	13594
Kernel/Userspace ticks	585/210 (795)	?	?	694/481 (1175)

t = 0:0.1:6.3; plot (t, cos(t), "-;cos(t);", t, sin(t), "+3;sin(t);"):

	with -O2	with -O1	with -O0	without anything
Number of syscalls	13765	?	?	13755
Kernel/Userspace ticks	610/424 (1034)	?	?	587/844 (1431)

coreutils: du command on large dir

	with -O2	with -O1	with -O0	without anything
Number of syscalls	303648	303648	303648	303648
Kernel/Userspace ticks	11388/307	11547/269	11297/341	11344/281

- almost no differences

RESTRICTION TO THE MEMORY SIZE

I use to run one process on comp with enough memory and with limited ammount of memory: (the limit was set only for this process - cgroups)

	without limit	limit 3Mb
Number of syscalls	40348	40367
Kernel/Userspace ticks	1143/3001 (4144)	5437/4168 (9605)
Read/Written bytes	5972809	5973681
Pooling syscalls	0	0

---

READ BY getc, gets with different buffer size

Playing with cat command:

version 1:

   while ( (c=getc(f)) != EOF) {
      putchar(c);
   }

version2:

   while ( (c=getc(f)) != EOF) {
       if (poc < 99) {
           str[poc]=(char )c;
           poc++;
       } else {
           printf("%s",str);
           poc = 0;
       }
       putchar(c);
   }

version3:

  #define MAX 100
  while ( (fgets(str,MAX, f)) != NULL) {
      puts(str);
  }

version4:

  #define MAX 1000
  while ( (fgets(str,MAX, f)) != NULL) {
      puts(str);
  }

Monitored execname:	cat	cat1	cat2	cat3	cat4	busybox- static	busybox
Number of syscalls:	51	2474	4410	5382	4865	109	142
Kernel/Userspace ticks:	8/0	38/13	59/13	61/5	50/7	13/0	7/0
Read/Written bytes:	204485	204485	204485	204485	204485	203749	204997
Pooling syscalls:	0	0	0	0	0	0	0