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Message-ID: <4992ABF1.3080007@redhat.com>
Date: Wed, 11 Feb 2009 11:44:01 +0100
From: Harald Hoyer <harald@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: power@...host.org
Subject: Re: [PATCH] tracer for sys_open() - sreadahead
Karel Zak wrote:
> On Mon, Feb 09, 2009 at 02:23:35PM +0100, Harald Hoyer wrote:
>> Karel Zak wrote:
>>> On Thu, Feb 05, 2009 at 03:44:42PM +0100, Harald Hoyer wrote:
>>>> Ingo Molnar wrote:
>>>>> * Pavel Machek <pavel@...e.cz> wrote:
>>>>>
>>>>>> On Tue 2009-01-27 12:08:04, Kok, Auke wrote:
>>>>>>> This tracer monitors regular file open() syscalls. This is a fast
>>>>>>> and low-overhead alternative to strace, and does not allow or
>>>>>>> require to be attached to every process.
>>>>>>>
>>>>>>> The tracer only logs succesfull calls, as those are the only ones we
>>>>>>> are currently interested in, and we can determine the absolute path
>>>>>>> of these files as we log.
>>>>>> Maybe fanotify() should be used instead?
>>>>>>
>>>>>> Or maybe just plain strace? One slow boot should not really hurt...
>>>>> ptrace is out of question for good tracing because it's not a
>>>>> transparent probe. (ptrace monopolizes the traced task - if we use
>>>>> that then we break regular strace usage.)
>>>>>
>>>>> Ingo
>>>> Can strace can be used on init?
>>>>
>>>> $ man strace
>>>> ...
>>>> On Linux, exciting as it would be, tracing the init process is forbidden.
>>>> ...
>>>>
>>>> Any hope getting _any_ mechanism in the kernel??
>>> Do you remember Linux Auditing System? That's RH's baby with hooks to
>>> all relevant syscalls. It would be better to fix/improve the current
>>> kernel mechanisms that introduce a new one.
>> Yes, I do remember it, because this is how the current fedora readahead
>> gathers its data. It delays the audit daemon, because there is no clean
>> way to hook into the stream. I asked to add a second "channel" (auditd
>> wants the kernel socket for its own)...
>
> yes, it'd be nice to support arbitrary number of connections and
> rules per connection. (.. or export audit stuff to userspace by a
> special pseudo filesystem (see cgroups, debugfs, ...)).
>
> Karel
>
right! if only someone would implement that *hint, hint* :-/
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