Re: [PATCH] tracer for sys_open() - sreadahead

[Harald Hoyer <harald@redhat.com>]

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@suse.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* :-/