Re: Performance analysis of Linux Kernel Markers 0.20 for 2.6.17
Mathieu Desnoyers <[email protected]>
| Newsgroups | gmane.linux.kernel,gmane.linux.kernel.tracing,gmane.linux.systemtap |
|---|---|
| Message-ID | <20061001034212.GB13527@Krystal> |
* Nicholas Miell ([email protected]) wrote: > On Sat, 2006-09-30 at 14:01 -0400, Mathieu Desnoyers wrote: > > Hi, > > > > Following the huge discussion thread about tracing/static vs dynamic > > instrumentation/markers, a consensus seems to emerge about the need for a > > marker system in the Linux kernel. The main issues this mechanism addresses are: > > > > - Identify code important to runtime data collection/analysis tools in tree so > > that it follows the code changes naturally. > > - Be visually appealing to kernel developers. > > - Have a very low impact on the system performance. > > - Integrate in the standard kernel infrastructure : use C and loadable modules. > > > > The time has come for some performance measurements of the Linux Kernel Markers, > > which follows. I attach a PDF with tables and charts which condense these > > results. > > Has anyone done any performance measurements with the "regular function > call replaced by a NOP" type of marker? > Here it is (on the same setup as the other tests : Pentium 4, 3 GHz) : * Execute an empty loop - Without marker NR_LOOPS : 10000000 time delta (cycles): 15026497 cycles per loop : 1.50 - With 5 NOPs NR_LOOPS : 100000 time delta (cycles): 300157 cycles per loop : 3.00 added cycles per loop for nops : 3.00-1.50 = 1.50 * Execute a loop of memcpy 4096 bytes - Without marker NR_LOOPS : 10000 time delta (cycles): 12981555 cycles per loop : 1298.16 - With 5 NOPs NR_LOOPS : 10000 time delta (cycles): 12983925 cycles per loop : 1298.39 added cycles per loop for nops : 0.23 If we compare this approach to the jump-over-call markers (in cycles per loop) : NOPs Jump over call generic Jump over call optimized empty loop 1.50 1.17 2.50 memcpy 0.23 2.12 0.07 Mathieu OpenPGP public key: http://krystal.dyndns.org:8080/key/compudj.gpg Key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68