On Thu, Oct 19, 2017 at 03:11:12PM +0900, Byungchul Park wrote: > On Thu, Oct 19, 2017 at 07:57:30AM +0200, Ingo Molnar wrote: > > > > * Byungchul Park <byungchul.park@xxxxxxx> 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? > > > 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 > > 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. Are you talking about the oops by 'null pointer dereference' by unwinder a few weeks ago? At the time, cross-release was falsely accused. AFAIK, cross-release has not crashed system yet. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
