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Re: djprobes status
- From: Satoshi Oshima <soshima at redhat dot com>
- To: "Frank Ch. Eigler" <fche at redhat dot com>
- Cc: systemtap at sources dot redhat dot com, Ingo Molnar <mingo at redhat dot com>
- Date: Fri, 15 Sep 2006 09:49:03 -0400
- Subject: Re: djprobes status
- References: <20060914184609.GA4577@redhat.com>
We are continuing to work on djprobes.
The problems currently we are trying to solve is...
(1)finding the safe place to put probes
(2)unregistration of the buffer that is used as out of line execution
under kernel level preemption(CONFIG_PREEMPT=y)
We have some idea to solve problem (1), and we are working on it.
Currently (2) is very difficult to solve. This problem is equivalent
to the problem of finding RCU quiescent state without rcu_read_lock()/
rcu_read_unlock(). We need to add a couple of primitives to find such
state. But it is not easy. We may be going to push djprobe without
kernel level preemption support like current kprobe-booster.
Frank Ch. Eigler wrote:
> Hi -
> Ingo asked me to find out the current status of djprobes-like
> technology in kprobes, and a list of the major technical problems that
> blocked further progress. Could someone who worked on that summarize?
> - FChE