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Date: Wed, 8 Apr 2009 13:06:02 +0200
From: Andi Kleen <andi@firstfloor.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: Masami Hiramatsu <mhiramat@redhat.com>,
       Frederic Weisbecker <fweisbec@gmail.com>,
       Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
       Jim Keniston <jkenisto@us.ibm.com>,
       Andrew Morton <akpm@linux-foundation.org>,
       Vegard Nossum <vegard.nossum@gmail.com>,
       "H. Peter Anvin" <hpa@zytor.com>, Steven Rostedt <rostedt@goodmis.org>,
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       Satoshi Oshima <satoshi.oshima.fk@hitachi.com>,
       systemtap-ml <systemtap@sources.redhat.com>,
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Subject: Re: [RFC][PROTO][PATCH -tip 0/7] kprobes: support jump optimization on x86
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References: <49DA7702.5030308@redhat.com> <20090408011743.GB5977@nowhere> <49DC0307.6080107@redhat.com> <20090408101056.GA14482@elte.hu>
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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.
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