Messages in this thread | | | Date | Fri, 15 Sep 2006 12:59:34 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH 0/11] LTTng-core (basic tracing infrastructure) 0.5.108 |
| |
On Fri, 15 Sep 2006 14:16:18 -0400 Karim Yaghmour <karim@opersys.com> wrote:
> > Although IMO this is a bit lame - it is quite possible to go into > > SexySystemTapGUI, click on a particular kernel file-n-line and have > > systemtap userspace keep track of that place in the kernel source across > > many kernel versions: all it needs to do is to remember the file+line and a > > snippet of the surrounding text, for readjustment purposes. > > Sure, if you're a kernel developer, but as I've explained numberous > times in this thread, there are far more many users of tracing than > kernel developers.
Disagree. I was describing a means by which a set of systemtap trace points could be described. A means which would allow those tracepoints to be maintained without human intervention as the kernel source changes. (ie: use a similar algorithm and representation as patch(1)).
Presumably those tracepoints would have been provided by a kernel developer and delivered to non-developers, just like static tracepoints.
> > (*) I don't buy the performance arguments: kprobes are quick, and I'd > > expect that the CPU consumption of the destination of the probe is > > comparable to or higher than the cost of taking the initial trap. > > Please see Mathieu's earlier posting of numbers comparing kprobes to > static points. Nevertheless, I do not believe that the use of kprobes > should be pitted against static instrumentation, the two are > orthogonal.
People have been speeding up kprobes in recent kernels, to avoid the int3 overhead. I don't recall seeing how effective that has been. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |