* Byungchul Park <byungchul.p...@lge.com> wrote:
> On Wed, Oct 18, 2017 at 12:09:44PM +0200, Ingo Molnar wrote:
> > BTW., have you attempted limiting the depth of the stack traces? I suspect
> > more
> > than 2-4 are rarely required to disambiguate the calling context.
>
> I did it for you. Let me show you the result.
>
> 1. No lockdep: 2.756558155 seconds time
> elapsed ( +- 0.09% )
> 2. Lockdep: 2.968710420 seconds time
> elapsed ( +- 0.12% )
> 3. Lockdep + Crossrelease 5 entries: 3.153839636 seconds time
> elapsed ( +- 0.31% )
> 4. Lockdep + Crossrelease 3 entries: 3.137205534 seconds time
> elapsed ( +- 0.87% )
> 5. Lockdep + Crossrelease + This patch: 2.963669551 seconds time
> elapsed ( +- 0.11% )
I think the lockdep + crossrelease + full-stack numbers are missing?
But yeah, looks like single-entry-stacktrace crossrelease only has a +0.2%
performance cost (with 0.1% noise), while lockdep itself has a +7.7% cost.
That's very reasonable and we can keep the single-entry cross-release feature
enabled by default as part of CONFIG_PROVE_LOCKING=y - assuming all the crashes
and false positives are fixed by the next merge window.
Thanks,
Ingo
