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SubjectRe: [PATCH] tracer for sys_open() - sreadahead
Karel Zak wrote:
> On Thu, Feb 05, 2009 at 03:44:42PM +0100, Harald Hoyer wrote:
>> Ingo Molnar wrote:
>>> * Pavel Machek <> 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.
> Karel

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)...

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