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Diffstat (limited to 'stapprobes.5.in')
| -rw-r--r-- | stapprobes.5.in | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/stapprobes.5.in b/stapprobes.5.in index 6d1df5a4..276358a0 100644 --- a/stapprobes.5.in +++ b/stapprobes.5.in @@ -41,6 +41,13 @@ sufficient. (Think vaguely of the prolog cut operator.) If it does resolve, then no further probe points in the same comma-separated list will be resolved. Therefore, the "!" sufficiency mark only makes sense in a list of probe point alternatives. +.PP +Additionally, a probe point may be followed by a "if (expr)" statement, in +order to enable/disable the probe point on-the-fly. With the "if" statement, +if the "expr" is false when the probe point is hit, the whole probe body +including alias's body is skipped. The condition is stacked up through +all levels of alias/wildcard expansion. So the final condition becomes +the logical-and of conditions of all expanded alias/wildcard. These are all syntactically valid probe points: @@ -52,6 +59,7 @@ end syscall.* kernel.function("no_such_function") ? module("awol").function("no_such_function") ! +signal.*? if (switch) .ESAMPLE Probes may be broadly classified into "synchronous" and |