Messages in this thread | | | Date | Thu, 19 Oct 2017 08:22:12 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH 1/2] lockdep: Introduce CROSSRELEASE_STACK_TRACE and make it not unwind as default |
| |
* Byungchul Park <byungchul.park@lge.com> wrote:
> On Thu, Oct 19, 2017 at 07:57:30AM +0200, Ingo Molnar wrote: > > > > * Byungchul Park <byungchul.park@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? > > Ah, the last version of crossrelease merged into vanilla, records 5 > entries, since I thought it overloads too much if full stack is used, > and 5 entries are enough. Don't you think so?
Ok, fair enough, I missed that limitation!
> > 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 > > BTW, is there any crash by cross-release I don't know? Of course, I know > cases of false positives, but I don't about crash.
There's no current crash regression that I know of - I'm just outlining the conditions of getting all this re-enabled in the next merge window.
Instead of sending two series, could you please send a series that includes both these fixing + re-enabling patches, plus the false positive fixes?
In particular I think the cross-release re-enabling should be done as the last patch, so that any future bisections of new false positives won't be made more difficult by re-introducing the old false positives near the end of the bisection.
Thanks,
Ingo
| |