[ltt-dev] performance results I measured with the latest lttng patches

[Jiaying Zhang]

Hi Mathieu,

On Thu, Sep 25, 2008 at 12:50 PM, Mathieu Desnoyers <
compudj at krystal.dyndns.org> wrote:

> * Jiaying Zhang (jiayingz at google.com) wrote:
> > Hi Jan,
> >
> > >
> > > > lttng-compiled-in, all markers disabled: Throughput 743.931 MB/sec
> > > > lttng-compiled-in, default markers enabled, taking an active trace in
> > > normal
> > > > mode: Throughput 500.24 MB/sec
> > >
> > > Isn't lttng-compile-out missing here? Or did you ran the same base
> kernel?
> >
> >
> > I used the same base kernel here.
> >
> > Jiaying
>
> To to give an idea of the order of magniture of kernel effect on tbench
> on my dual 4-cores box Intel box :
>
> stock kernel 2.6.27-rc6 : 2024MB/s
> stock kernel 2.6.27-rc7 : 1989MB/s
>
> 1.7% slowdown, with exactly the same config. And this is between
> rc releases where the diff consists mostly of _bugfixes_.


So do both kernels have LTTng compiled in but disabled?
It is possible to see variance with difference kernel versions.
To focus on the performance effects of Lttng, I guess we should
stick with the same kernel version with difference Lttng configurations.


> I start to doubt tbench represents well "real" workloads, given it's
> mostly doing kernel interaction and almost nothing in userspace.


There are many kinds of "real" workloads. I think we may want to pay
special attentions to those benchmarks that stress Lttng.

Jiaying


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