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Re: [RFC][PROTO][PATCH -tip 0/7] kprobes: support jump optimization on x86
- From: Andi Kleen <andi at firstfloor dot org>
- To: Ingo Molnar <mingo at elte dot hu>
- Cc: Masami Hiramatsu <mhiramat at redhat dot com>, Frederic Weisbecker <fweisbec at gmail dot com>, Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>, Jim Keniston <jkenisto at us dot ibm dot com>, Andrew Morton <akpm at linux-foundation dot org>, Vegard Nossum <vegard dot nossum at gmail dot com>, "H. Peter Anvin" <hpa at zytor dot com>, Steven Rostedt <rostedt at goodmis dot org>, Andi Kleen <andi at firstfloor dot org>, Avi Kivity <avi at redhat dot com>, "Frank Ch. Eigler" <fche at redhat dot com>, Satoshi Oshima <satoshi dot oshima dot fk at hitachi dot com>, systemtap-ml <systemtap at sources dot redhat dot com>, LKML <linux-kernel at vger dot kernel dot org>
- Date: Wed, 8 Apr 2009 13:06:02 +0200
- Subject: Re: [RFC][PROTO][PATCH -tip 0/7] kprobes: support jump optimization on x86
- References: <49DA7702.5030308@redhat.com> <20090408011743.GB5977@nowhere> <49DC0307.6080107@redhat.com> <20090408101056.GA14482@elte.hu>
On Wed, Apr 08, 2009 at 12:10:56PM +0200, Ingo Molnar wrote:
>
> * Masami Hiramatsu <mhiramat@redhat.com> wrote:
>
> > > But can we consider it as a small problem, assuming that kprobes
> > > are rarely intended for a massive use in once? I guess that
> > > usually, not a lot of functions are probed simultaneously.
> >
> > Hm, yes and no, systemtap may use massive kprobes, because it
> > supports "wildcard" probes. However, optimizing in default may be
> > acceptable.
>
> I'm curious: what is the biggest kprobe count you've ever seen, in
> the field? 1000? 10,000? 100,000? More?
The limit is iirc how much memory the gcc compiling the probes program
consumes before running out of swap space.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.