Re: LTTng "TIF_KERNEL_TRACE"

[Mathieu Desnoyers]

* Ingo Molnar (mingo@xxxxxxx) wrote:
> 
> * Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxx> wrote:
> 
> > Hi Ingo,
> > 
> > Looking at the current -tip tree, I notice that the 
> > TIF_SYSCALL_FTRACE flag is only implemented for x86.
> > 
> > I have TIF_KERNEL_TRACE in my lttng tree which applies to all 
> > architectures to do the exact same thing :
> > 
> > lttng-kernel-trace-thread-flag-alpha.patch
> > lttng-kernel-trace-thread-flag-arm.patch
> > lttng-kernel-trace-thread-flag-avr32.patch
> > lttng-kernel-trace-thread-flag-blackfin.patch
> > lttng-kernel-trace-thread-flag-cris.patch
> > lttng-kernel-trace-thread-flag-frv.patch
> > lttng-kernel-trace-thread-flag-h8300.patch
> > lttng-kernel-trace-thread-flag-ia64.patch
> > lttng-kernel-trace-thread-flag-m32r.patch
> > lttng-kernel-trace-thread-flag-m68k.patch
> > lttng-kernel-trace-thread-flag-mips.patch
> > lttng-kernel-trace-thread-flag-parisc.patch
> > lttng-kernel-trace-thread-flag-powerpc.patch
> > lttng-kernel-trace-thread-flag-s390.patch
> > lttng-kernel-trace-thread-flag-sh.patch
> > lttng-kernel-trace-thread-flag-sparc.patch
> > lttng-kernel-trace-thread-flag-um.patch
> > lttng-kernel-trace-thread-flag-x86.patch
> > lttng-kernel-trace-thread-flag-xtensa.patch
> > lttng-kernel-trace-thread-flag-api.patch
> > 
> > Is there any way we could get this merged ?
> > 
> > One thing I like about the name TIF_KERNEL_TRACE compared to 
> > TIF_SYSCALL_FTRACE is that it gives us a per-thread flag that 
> > could eventually be used for more kernel tracing purposes than 
> > just syscalls.
> 
> Yeah - TIF_KERNEL_TRACE indeed sounds more descriptive and less 
> restrictive. TIF_SYSCALL_FTRACE was a bit ad-hoc.
> 
> 	Ingo

lttng-kernel-trace-thread-flag-api.patch adds the enable/disable API,
with refcount, in kernel/sched.c just because I did not know where to
put it. Should we move this to its own file in kernel/trace/???.c ?

One option is kernel/trace/trace.c, which is compiled as soon as
CONFIG_TRACING is enabled.

I added the prototypes to linux/sched.h, they should probably be moved
to... linux/trace.h ?

Mathieu

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Mathieu Desnoyers
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