Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758836AbbEFDoz (ORCPT ); Tue, 5 May 2015 23:44:55 -0400 Received: from mail-wi0-f177.google.com ([209.85.212.177]:35356 "EHLO mail-wi0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757696AbbEFDox (ORCPT ); Tue, 5 May 2015 23:44:53 -0400 Message-ID: <1430883894.3805.2.camel@gmail.com> Subject: Re: question about RCU dynticks_nesting From: Mike Galbraith To: paulmck@linux.vnet.ibm.com Cc: Rik van Riel , Paolo Bonzini , Ingo Molnar , Andy Lutomirski , "linux-kernel@vger.kernel.org" , X86 ML , williams@redhat.com, Andrew Lutomirski , fweisbec@redhat.com, Peter Zijlstra , Heiko Carstens , Thomas Gleixner , Ingo Molnar , Linus Torvalds Date: Wed, 06 May 2015 05:44:54 +0200 In-Reply-To: <1430876985.3169.4.camel@gmail.com> References: <20150502052733.GA9983@gmail.com> <55473B47.6080600@redhat.com> <55479749.7070608@redhat.com> <20150504183906.GS5381@linux.vnet.ibm.com> <5547CAED.9010201@redhat.com> <20150504200232.GB5381@linux.vnet.ibm.com> <5547D2FE.9010806@redhat.com> <20150504203801.GG5381@linux.vnet.ibm.com> <5547DC3C.1000504@redhat.com> <20150505055413.GJ5381@linux.vnet.ibm.com> <1430876985.3169.4.camel@gmail.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.11 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5219 Lines: 58 On Wed, 2015-05-06 at 03:49 +0200, Mike Galbraith wrote: > On Mon, 2015-05-04 at 22:54 -0700, Paul E. McKenney wrote: > > > You have RCU_FAST_NO_HZ=y, correct? Could you please try measuring with > > RCU_FAST_NO_HZ=n? > > FWIW, the syscall numbers I posted were RCU_FAST_NO_HZ=n. (I didn't > profile to see where costs lie though) (did that) 100000000 * stat() on isolated cpu NO_HZ_FULL off inactive housekeeper nohz_full real 0m14.266s 0m14.367s 0m20.427s 0m27.921s user 0m1.756s 0m1.553s 0m1.976s 0m10.447s sys 0m12.508s 0m12.769s 0m18.400s 0m17.464s (real) 1.000 1.007 1.431 1.957 inactive housekeeper nohz_full ---------------------------------------------------------------------------------------------------------------------------------------------- 7.61% [.] __xstat64 11.12% [k] context_tracking_exit 7.41% [k] context_tracking_exit 7.04% [k] system_call 6.18% [k] context_tracking_enter 6.02% [k] native_sched_clock 6.96% [k] copy_user_enhanced_fast_string 5.18% [.] __xstat64 4.69% [k] rcu_eqs_enter_common.isra.37 6.57% [k] path_init 4.89% [k] system_call 4.35% [k] _raw_spin_lock 5.92% [k] system_call_after_swapgs 4.84% [k] copy_user_enhanced_fast_string 4.30% [k] context_tracking_enter 5.44% [k] lockref_put_return 4.46% [k] path_init 4.25% [k] kmem_cache_alloc 4.69% [k] link_path_walk 4.30% [k] system_call_after_swapgs 4.14% [.] __xstat64 4.47% [k] lockref_get_not_dead 4.12% [k] kmem_cache_free 3.89% [k] rcu_eqs_exit_common.isra.38 4.46% [k] kmem_cache_free 3.78% [k] link_path_walk 3.50% [k] system_call 4.20% [k] kmem_cache_alloc 3.62% [k] lockref_put_return 3.48% [k] copy_user_enhanced_fast_string 4.09% [k] cp_new_stat 3.43% [k] kmem_cache_alloc 3.02% [k] system_call_after_swapgs 3.38% [k] vfs_getattr_nosec 2.95% [k] lockref_get_not_dead 2.97% [k] kmem_cache_free 2.82% [k] vfs_fstatat 2.87% [k] cp_new_stat 2.88% [k] lockref_put_return 2.60% [k] user_path_at_empty 2.62% [k] syscall_trace_leave 2.61% [k] link_path_walk 2.47% [k] path_lookupat 1.91% [k] vfs_getattr_nosec 2.58% [k] path_init 2.14% [k] strncpy_from_user 1.89% [k] syscall_trace_enter_phase1 2.15% [k] lockref_get_not_dead 2.11% [k] getname_flags 1.77% [k] path_lookupat 2.04% [k] cp_new_stat 2.10% [k] generic_fillattr 1.67% [k] complete_walk 1.89% [k] generic_fillattr 2.05% [.] main 1.65% [k] vfs_fstatat 1.67% [k] syscall_trace_leave 1.89% [k] complete_walk 1.56% [k] generic_fillattr 1.59% [k] vfs_getattr_nosec 1.73% [k] generic_permission 1.55% [k] user_path_at_empty 1.49% [k] get_vtime_delta 1.50% [k] system_call_fastpath 1.54% [k] strncpy_from_user 1.32% [k] user_path_at_empty 1.37% [k] legitimize_mnt 1.53% [k] getname_flags 1.30% [k] syscall_trace_enter_phase1 1.30% [k] dput 1.46% [k] legitimize_mnt 1.21% [k] rcu_eqs_exit 1.26% [k] putname 1.34% [.] main 1.21% [k] vfs_fstatat 1.19% [k] path_put 1.32% [k] int_with_check 1.18% [k] path_lookupat 1.18% [k] filename_lookup 1.28% [k] generic_permission 1.15% [k] getname_flags 1.01% [k] SYSC_newstat 1.16% [k] int_very_careful 1.03% [k] strncpy_from_user 0.96% [k] mntput_no_expire 1.04% [k] putname 1.01% [k] account_system_time 0.79% [k] path_cleanup 0.94% [k] dput 1.00% [k] complete_walk 0.79% [k] mntput 0.91% [k] context_tracking_user_exit 0.99% [k] vtime_account_user -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/