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Date: Wed, 08 Apr 2009 08:00:34 -0700
From: Masami Hiramatsu <mhiramat@redhat.com>
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To: "Frank Ch. Eigler" <fche@redhat.com>
CC: Andi Kleen <andi@firstfloor.org>, Ingo Molnar <mingo@elte.hu>,
       Frederic Weisbecker <fweisbec@gmail.com>,
       Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
       Jim Keniston <jkenisto@us.ibm.com>,
       Andrew Morton <akpm@linux-foundation.org>,
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       "H. Peter Anvin" <hpa@zytor.com>, Steven Rostedt <rostedt@goodmis.org>,
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       Satoshi Oshima <satoshi.oshima.fk@hitachi.com>,
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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>
In-Reply-To: <20090408130150.GC13827@redhat.com>
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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

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