Re: [MOCKUP] x86/mm: Lightweight lazy mm refcounting

2020-12-03 Thread Andy Lutomirski
> On Dec 3, 2020, at 2:13 PM, Nicholas Piggin wrote: > > Excerpts from Peter Zijlstra's message of December 3, 2020 6:44 pm: >>> On Wed, Dec 02, 2020 at 09:25:51PM -0800, Andy Lutomirski wrote: >>> >>> power: same as ARM, except that the loop may be rather larger since >>> the systems are big

Re: [MOCKUP] x86/mm: Lightweight lazy mm refcounting

2020-12-03 Thread Nicholas Piggin
Excerpts from Peter Zijlstra's message of December 3, 2020 6:44 pm: > On Wed, Dec 02, 2020 at 09:25:51PM -0800, Andy Lutomirski wrote: > >> power: same as ARM, except that the loop may be rather larger since >> the systems are bigger. But I imagine it's still faster than Nick's >> approach -- a c

Re: [MOCKUP] x86/mm: Lightweight lazy mm refcounting

2020-12-03 Thread Rik van Riel
On Thu, 2020-12-03 at 12:31 +, Matthew Wilcox wrote: > And this just makes me think RCU freeing of mm_struct. I'm sure it's > more complicated than that (then, or now), but if an anonymous > process > is borrowing a freed mm, and the mm is freed by RCU then it will not > go > away until the t

Re: [MOCKUP] x86/mm: Lightweight lazy mm refcounting

2020-12-03 Thread Matthew Wilcox
On Wed, Dec 02, 2020 at 09:25:51PM -0800, Andy Lutomirski wrote: > This code compiles, but I haven't even tried to boot it. The earlier > part of the series isn't terribly interesting -- it's a handful of > cleanups that remove all reads of ->active_mm from arch/x86. I've > been meaning to do tha

Re: [MOCKUP] x86/mm: Lightweight lazy mm refcounting

2020-12-03 Thread Peter Zijlstra
On Wed, Dec 02, 2020 at 09:25:51PM -0800, Andy Lutomirski wrote: > power: same as ARM, except that the loop may be rather larger since > the systems are bigger. But I imagine it's still faster than Nick's > approach -- a cmpxchg to a remote cacheline should still be faster than > an IPI shootdown

Re: [MOCKUP] x86/mm: Lightweight lazy mm refcounting

2020-12-02 Thread kernel test robot
Hi Andy, I love your patch! Yet something to improve: [auto build test ERROR on tip/x86/core] [also build test ERROR on tip/x86/mm soc/for-next linus/master v5.10-rc6 next-20201201] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to u