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Re: [RFC][PROTO][PATCH -tip 0/7] kprobes: support jump optimization on x86
- From: Masami Hiramatsu <mhiramat at redhat dot com>
- To: "Frank Ch. Eigler" <fche at redhat dot com>
- Cc: Andi Kleen <andi at firstfloor dot org>, Ingo Molnar <mingo at elte dot hu>, 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, 08 Apr 2009 08:00:34 -0700
- 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> <20090408130150.GC13827@redhat.com>
Frank Ch. Eigler wrote:
> 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.
Hm, when 40,000 kprobes are optimized, it will consume less than 8MB ...
I guess that is acceptable for recent machines.
Thank you,
--
Masami Hiramatsu
Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division
e-mail: mhiramat@redhat.com