Re: [patch V2 20/29] x86/dumpstack/64: Speedup in_exception_stack()

2019-04-05 Thread Thomas Gleixner
On Fri, 5 Apr 2019, Josh Poimboeuf wrote: > On Fri, Apr 05, 2019 at 05:07:18PM +0200, Thomas Gleixner wrote: > > The current implementation of in_exception_stack() iterates over the > > exception stacks array. Most of the time this is an useless exercise, but > > even for the actual use cases

Re: [patch V2 20/29] x86/dumpstack/64: Speedup in_exception_stack()

2019-04-05 Thread Josh Poimboeuf
On Fri, Apr 05, 2019 at 05:07:18PM +0200, Thomas Gleixner wrote: > The current implementation of in_exception_stack() iterates over the > exception stacks array. Most of the time this is an useless exercise, but > even for the actual use cases (perf and ftrace) it takes at least 2 > iterations to

[patch V2 20/29] x86/dumpstack/64: Speedup in_exception_stack()

2019-04-05 Thread Thomas Gleixner
The current implementation of in_exception_stack() iterates over the exception stacks array. Most of the time this is an useless exercise, but even for the actual use cases (perf and ftrace) it takes at least 2 iterations to get to the NMI stack. As the exception stacks and the guard pages are