Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752812AbcCYNRk (ORCPT ); Fri, 25 Mar 2016 09:17:40 -0400 Received: from mail-wm0-f52.google.com ([74.125.82.52]:37761 "EHLO mail-wm0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751683AbcCYNRi (ORCPT ); Fri, 25 Mar 2016 09:17:38 -0400 Date: Fri, 25 Mar 2016 14:17:34 +0100 From: Frederic Weisbecker To: Ingo Molnar Cc: LKML , Peter Zijlstra , Linus Torvalds , Thomas Gleixner , Andrew Morton Subject: Re: [PATCH 0/3] nohz: Convert tick dependency mask to atomic_t Message-ID: <20160325131732.GA16488@lerouge> References: <1458830281-4255-1-git-send-email-fweisbec@gmail.com> <20160325084847.GA15235@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160325084847.GA15235@gmail.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4403 Lines: 73 On Fri, Mar 25, 2016 at 09:48:47AM +0100, Ingo Molnar wrote: > > * Frederic Weisbecker wrote: > > > As per Linus suggestion, lets convert the tick dependency mask to > > atomic_t. Introduce atomic_fetch_or() and confine fetch_or() back to > > scheduler guts. > > > > git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git > > timers/nohz > > > > HEAD: 7b7e5da5733f58668181077ec394a718e08c392c > > > > Thanks, > > Frederic > > --- > > > > Frederic Weisbecker (3): > > atomic: Introduce atomic_fetch_or > > nohz: Convert tick dependency mask to atomic_t > > Revert "atomic: Export fetch_or()" > > > > > > include/linux/atomic.h | 34 +++++++++++++-------------- > > include/linux/sched.h | 4 ++-- > > kernel/sched/core.c | 18 ++++++++++++++ > > kernel/time/tick-sched.c | 61 ++++++++++++++++++++++++------------------------ > > kernel/time/tick-sched.h | 2 +- > > 5 files changed, 68 insertions(+), 51 deletions(-) > > Could you please also convert the sched/core.c usage, so that we can get rid of > the private fetch_or() definition? Please also double check that it does not > result in worse code generation. That involve converting thread_info::flags to atomic_t and given how much the type varies across architectures: $ grep 'flags;' $(ls arch/*/include/asm/thread_info.h) arch/alpha/include/asm/thread_info.h: unsigned int flags; /* low level flags */ arch/arc/include/asm/thread_info.h: unsigned long flags; /* low level flags */ arch/arm64/include/asm/thread_info.h: unsigned long flags; /* low level flags */ arch/arm/include/asm/thread_info.h: unsigned long flags; /* low level flags */ arch/avr32/include/asm/thread_info.h: unsigned long flags; /* low level flags */ arch/blackfin/include/asm/thread_info.h: unsigned long flags; /* low level flags */ arch/c6x/include/asm/thread_info.h: unsigned long flags; /* low level flags */ arch/cris/include/asm/thread_info.h: unsigned long flags; /* low level flags */ arch/frv/include/asm/thread_info.h: unsigned long flags; /* low level flags */ arch/h8300/include/asm/thread_info.h: unsigned long flags; /* low level flags */ arch/hexagon/include/asm/thread_info.h: unsigned long flags; /* low level flags */ arch/ia64/include/asm/thread_info.h: __u32 flags; /* thread_info flags (see TIF_*) */ arch/m32r/include/asm/thread_info.h: unsigned long flags; /* low level flags */ arch/m68k/include/asm/thread_info.h: unsigned long flags; arch/metag/include/asm/thread_info.h: unsigned long flags; /* low level flags */ arch/microblaze/include/asm/thread_info.h: unsigned long flags; /* low level flags */ arch/mips/include/asm/thread_info.h: unsigned long flags; /* low level flags */ arch/mn10300/include/asm/thread_info.h: unsigned long flags; /* low level flags */ arch/nios2/include/asm/thread_info.h: unsigned long flags; /* low level flags */ arch/openrisc/include/asm/thread_info.h: unsigned long flags; /* low level flags */ arch/parisc/include/asm/thread_info.h: unsigned long flags; /* thread_info flags (see TIF_*) */ arch/powerpc/include/asm/thread_info.h: unsigned long local_flags; /* private flags for thread */ arch/s390/include/asm/thread_info.h: unsigned long flags; /* low level flags */ arch/score/include/asm/thread_info.h: unsigned long flags; /* low level flags */ arch/sh/include/asm/thread_info.h: unsigned long flags; /* low level flags */ arch/tile/include/asm/thread_info.h: unsigned long flags; /* low level flags */ arch/um/include/asm/thread_info.h: unsigned long flags; /* low level flags */ arch/unicore32/include/asm/thread_info.h: unsigned long flags; /* low level flags */ arch/x86/include/asm/thread_info.h: __u32 flags; /* low level flags */ arch/xtensa/include/asm/thread_info.h: unsigned long flags; /* low level flags */ also given how much it is accessed (and that happens a lot in ASM as well). This conversion deserves quite a whole project on its own. It might be possible to do it incrementally though.