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stapex
Langue: en
Version: 2007-08-21 (fedora - 25/11/07)
Section: 5 (Format de fichier)
Sommaire
NAME
stapex - systemtap examplesLANGUAGE BASICS
These examples give a feel for basic systemtap syntax and control structures.-
global odds, evens probe begin { # "no" and "ne" are local integers for (i=0; i<10; i++) { if (i % 2) odds [no++] = i else evens [ne++] = i } delete odds[2] delete evens[3] exit () } probe end { foreach (x+ in odds) { printf ("odds[%d] = %d, x, odds[x]) } foreach (x in evens-) { printf ("evens[%d] = %d, x, evens[x]) } }
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odds[1] = 1 odds[3] = 5 odds[4] = 7 odds[5] = 9 evens[5] = 8 evens[4] = 6 evens[2] = 2 evens[1] = 0
This script prints the primes between 0 and 49.
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function isprime (x) { if (x < 2) return 0 for (i=2; i<x; i++) { if (x % i == 0) return 0 if (i * i > x) break } return 1 } probe begin { for (i=0; i<50; i++) if (isprime (i)) printf("%d, i) exit() }
This script demonstrates recursive functions.
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function fibonacci(i) { if (i < 1) error ("bad number") if (i == 1) return 1 if (i == 2) return 2 return fibonacci (i-1) + fibonacci (i-2) } probe begin { printf ("11th fibonacci number: %d, fibonacci (11)) exit () }
PROBING
To trace entry and exit from a function, use a pair of probes:
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probe kernel.function("sys_mkdir") { log ("enter") } probe kernel.function("sys_mkdir").return { log ("exit") }
To list the probeable functions in the kernel, use the last-pass option to the translator. That output needs to be filtered because each inlined function instance is listed separately.
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% stap -p2 -e 'probe kernel.function("*") {}' | sort | uniq
SEE ALSO
/usr/doc/systemtap*/examples stap(1) stapprobes(5) stapfuncs(5)Contenus ©2006-2024 Benjamin Poulain
Design ©2006-2024 Maxime Vantorre