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[Bug translator/10045] New: process.syscall(NUM) probes
- From: "fche at redhat dot com" <sourceware-bugzilla at sourceware dot org>
- To: systemtap at sources dot redhat dot com
- Date: 8 Apr 2009 12:27:31 -0000
- Subject: [Bug translator/10045] New: process.syscall(NUM) probes
- Reply-to: sourceware-bugzilla at sourceware dot org
In the future, we will probably extend or twin the syscall.* tapset
to utrace-based high-performance probes. However, utrace per se doesn't
provide efficient per-syscall-type filtering, so if it were implemented
thusly:
probe process.syscall.read = process.syscall {
if ($syscall_nr!=30) next
arg1=@cast(...)
}
....
then multiple syscall probes can't be very efficiently implemented,
since it would translate to a chain of if/else's or worse, just to
evaluate the syscall_nr comparison/rejection logic.
If OTOH the syscall number was pushed into the probe point, as in
probe process.syscall(NUM) {...}
then the translator can emit a more efficient switch block in case
of multiple syscall probes.
--
Summary: process.syscall(NUM) probes
Product: systemtap
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: translator
AssignedTo: systemtap at sources dot redhat dot com
ReportedBy: fche at redhat dot com
http://sourceware.org/bugzilla/show_bug.cgi?id=10045
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