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Re: [RFC 5/5] uprobes: add global breakpoints
- From: Sebastian Andrzej Siewior <bigeasy at linutronix dot de>
- To: Peter Zijlstra <a dot p dot zijlstra at chello dot nl>
- Cc: linux-kernel at vger dot kernel dot org, x86 at kernel dot org, Arnaldo Carvalho de Melo <acme at ghostprotocols dot net>, Roland McGrath <roland at redhat dot com>, Oleg Nesterov <oleg at redhat dot com>, Srikar Dronamraju <srikar at linux dot vnet dot ibm dot com>, Ananth N Mavinakaynahalli <ananth at in dot ibm dot com>, stan_shebs at mentor dot com, gdb-patches at sourceware dot org
- Date: Mon, 20 Aug 2012 17:26:44 +0200
- Subject: Re: [RFC 5/5] uprobes: add global breakpoints
- References: <1344355952-2382-1-git-send-email-bigeasy@linutronix.de> <1344355952-2382-6-git-send-email-bigeasy@linutronix.de> <1344857686.31459.25.camel@twins>
On 08/13/2012 01:34 PM, Peter Zijlstra wrote:
I'm not really happy with any of this. I would suggest limiting this
stuff much further, like say only have it affect ptraced
processes/tasks. That way you cannot accidentally freeze the entire
system into oblivion.
I'be been browsing over the cgroup Documentation and it seems to look
usefull. What I have in mind is the following:
/sys/fs/cgroup/gb
The root group is the default one where a breakpoint triggers. Below
you could have two groups:
- excluded
- active
The excluded group would never trigger a breakpoint.
Once a task in the root set triggers a breakpoint it will be moved into
to the active set. The eventfd notifcation API of cgroups could be used
to learn about this change.
The whole concept fails if the user does not move a single task into
the excluded group. To be overprotective here, I could try not do
anything until we have at least one pid in the "excluded" set.
So far I like this, it could be heat though.
Sebastian