Features/PowerManagement/scomes

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Please see Features/PowerManagement for more.

Contents

scomes

Scomes is a SystemTap script to watch resources consumed by the program. Now it is part of the tuned project (tuned-utils package).

Goal:

  • Measure amount of system resources consumed by the program.
  • Use these data to compare different programming techniques in view of system resources.
  • Create programming tips based on these results.


How it works: using systemtap - http://sources.redhat.com/systemtap/wiki/ script watches given binary for syscalls, kernel and userspace ticks, read and written bytes, transmitted bytes and polling syscalls, and enumerates score from these values.


scomes is part of tuned-utils package.

Usage

Prepare your system:

# yum install systemtap tuned-utils
# debuginfo-install kernel


Run scomes.stp

Binary you want to measure should be named uniquely (or ensure there are no other binaries with same name running on the system).

Now run the scomes with the command-line option being name of the binary and then run the binary:

# scomes.stp -c "<binary> [<binary arg> ...]" <timer>   # wait untill it starts
binary [binary args ...]
measured program
timer
how often you want to see current results, value is in seconds and 0 means "show only last results"

scomes will start to output statistics each <timer> seconds and once binary ends, it will output final statistic like this:

# ./scomes.stp -c "/bin/sleep 4" 2
Collecting data...
-----------------------------------
Monitored execname: sleep
Number of syscalls: 59
Kernel/Userspace ticks: 3/1 (4)
Read/Written bytes: 3620/0 (3620)
Transmitted/Recived bytes: 0/0 (0)
Pooling syscalls: 0
SCORE: 36205
-----------------------------------
Monitored execname: sleep
Number of syscalls: 59
Kernel/Userspace ticks: 3/1 (4)
Read/Written bytes: 3620/0 (3620)
Transmitted/Recived bytes: 0/0 (0)
Pooling syscalls: 0
SCORE: 36205
-----------------------------------
LAST RESULTS:
-----------------------------------
Monitored execname: sleep
Number of syscalls: 63
Kernel/Userspace ticks: 4/1 (5)
Read/Written bytes: 3620/0 (3620)
Transmitted/Recived bytes: 0/0 (0)
Pooling syscalls: 1
SCORE: 36206
-----------------------------------
QUITTING
-----------------------------------

Note: on F11 please call scomes with `stap --skip-badvars scomes.stp`.

Explain statistics

Monitored execname
name of the binary (passed as a command-line argument)
Number of syscalls
number of all syscalls performed by the binary
Kernel/Userspace ticks
count of the processor ticks binary uses in the kernel or in userspace respectively (`kticks` and `uticks` variables)
Read/Written bytes
sum of the read and written bytes from the file binary does (`reads, writes` variables)
Transmitted/Recived bytes
sum of the read and written bytes from the network binary does (`ifxmit` and `ifrecv` variables)
Polling syscalls
"bad" polling syscals binary does (poll, select, epoll, itimer, futex, nanosleep, signal)
SCORE
TODO - but for now: `SCORE = kticks + 2*uticks + 10*(reads+writes) + ifxmit + ifrecv`

First examples

http://fedoraproject.org/wiki/Features/PowerManagement/scomes/examples

command sleep 10

normal:

Monitored execname: sleep
Number of syscalls: 33
Kernel/Userspace ticks: 2/0
Read/Written bytes: 736
Transmitted/Recived bytes: 0
Pooling syscalls: 1
SCORE: 7362

busybox - statically linked:

Monitored execname: busybox
Number of syscalls: 7
Kernel/Userspace ticks: 1/0
Read/Written bytes: 0
Transmitted/Recived bytes: 0
Pooling syscalls: 1
SCORE: 1

busybox.anaconda - dynamically linked:

Monitored execname: sleep
Number of syscalls: 39
Kernel/Userspace ticks: 0/2
Read/Written bytes: 1248
Transmitted/Recived bytes: 0
Pooling syscalls: 0
SCORE: 12484