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Re: [RFC][PROTO][PATCH -tip 0/7] kprobes: support jump optimization on x86
- From: "Frank Ch. Eigler" <fche at redhat dot com>
- To: Andi Kleen <andi at firstfloor dot org>
- Cc: Ingo Molnar <mingo at elte dot hu>, 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>, Avi Kivity <avi 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 09:01:50 -0400
- 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> <20090408110602.GA14687@one.firstfloor.org>
On Wed, Apr 08, 2009 at 01:06:02PM +0200, Andi Kleen wrote:
> [...]
> > 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.
On a machine with lots of free RAM, gcc will not hold itself back. On
my home server, a 40000-kprobe script compiled (pass 4) in about 4
seconds using about 200MB RAM.
- FChE