LTTng 0.51, improved timestamping

LTTng 0.51, improved timestamping

[Mathieu Desnoyers]

Hi,

LTTng 0.51 for 2.6.27.4 does the following :

It improves timestamping on architectures with non-synchronized TSCs in
LTTng 0.51. I also now use per-cpu timers to do some time-related stuff
I previously used IPIs for. It involves being more closely tied to the
CPU hotplug callbacks.

I also replaced x86 tsc_sync.c test by LTTng architecture independent
test. (this will be posted separately on LKML for 2.6.28-rc3 tomorrow
along with the "tracer clock" patchset).

The event trap_entry, syscall_entry, irq_entry, softirq entry, exit and
raise now use smaller fields (2 bytes), which should be enough to encode
the IDs for all architectures. This will principally make a difference
with non-aligned tracing for most of those events.

Mathieu

-- 
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

Re: [ltt-dev] LTTng 0.51, improved timestamping

[Mathieu Desnoyers]

disable tsc synth when ! trace clock ?
tsc synth get/put ?

amd64 :
- single cpu -> tsc_is_sync : no force on unstable tsc ?
- hotplug out all cpus, recheck



* Mathieu Desnoyers (compudj@krystal.dyndns.org) wrote:
> Hi,
> 
> LTTng 0.51 for 2.6.27.4 does the following :
> 
> It improves timestamping on architectures with non-synchronized TSCs in
> LTTng 0.51. I also now use per-cpu timers to do some time-related stuff
> I previously used IPIs for. It involves being more closely tied to the
> CPU hotplug callbacks.
> 
> I also replaced x86 tsc_sync.c test by LTTng architecture independent
> test. (this will be posted separately on LKML for 2.6.28-rc3 tomorrow
> along with the "tracer clock" patchset).
> 
> The event trap_entry, syscall_entry, irq_entry, softirq entry, exit and
> raise now use smaller fields (2 bytes), which should be enough to encode
> the IDs for all architectures. This will principally make a difference
> with non-aligned tracing for most of those events.
> 
> Mathieu
> 
> -- 
> Mathieu Desnoyers
> OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
> 
> _______________________________________________
> ltt-dev mailing list
> ltt-dev@lists.casi.polymtl.ca
> http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev
> 

-- 
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

Re: [ltt-dev] LTTng 0.51, improved timestamping

[Mathieu Desnoyers]

Please ignore this last message. As some of you may have noticed, this
is actually the result of a brainstorming while being half-asleep. Those
things will be carefully looked at this morning. ;)

Mathieu

* Mathieu Desnoyers (compudj@krystal.dyndns.org) wrote:
> disable tsc synth when ! trace clock ?
> tsc synth get/put ?
> 
> amd64 :
> - single cpu -> tsc_is_sync : no force on unstable tsc ?
> - hotplug out all cpus, recheck
> 
> 
> 
> * Mathieu Desnoyers (compudj@krystal.dyndns.org) wrote:
> > Hi,
> > 
> > LTTng 0.51 for 2.6.27.4 does the following :
> > 
> > It improves timestamping on architectures with non-synchronized TSCs in
> > LTTng 0.51. I also now use per-cpu timers to do some time-related stuff
> > I previously used IPIs for. It involves being more closely tied to the
> > CPU hotplug callbacks.
> > 
> > I also replaced x86 tsc_sync.c test by LTTng architecture independent
> > test. (this will be posted separately on LKML for 2.6.28-rc3 tomorrow
> > along with the "tracer clock" patchset).
> > 
> > The event trap_entry, syscall_entry, irq_entry, softirq entry, exit and
> > raise now use smaller fields (2 bytes), which should be enough to encode
> > the IDs for all architectures. This will principally make a difference
> > with non-aligned tracing for most of those events.
> > 
> > Mathieu
> > 
> > -- 
> > Mathieu Desnoyers
> > OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
> > 
> > _______________________________________________
> > ltt-dev mailing list
> > ltt-dev@lists.casi.polymtl.ca
> > http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev
> > 
> 
> -- 
> Mathieu Desnoyers
> OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

-- 
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68