Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760508Ab2FHOvc (ORCPT ); Fri, 8 Jun 2012 10:51:32 -0400 Received: from terminus.zytor.com ([198.137.202.10]:59606 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756915Ab2FHOvP (ORCPT ); Fri, 8 Jun 2012 10:51:15 -0400 Date: Fri, 8 Jun 2012 07:51:04 -0700 From: tip-bot for Alexander Gordeev Message-ID: Cc: linux-kernel@vger.kernel.org, agordeev@redhat.com, hpa@zytor.com, mingo@kernel.org, yinghai@kernel.org, suresh.b.siddha@intel.com, tglx@linutronix.de Reply-To: mingo@kernel.org, hpa@zytor.com, agordeev@redhat.com, linux-kernel@vger.kernel.org, yinghai@kernel.org, suresh.b.siddha@intel.com, tglx@linutronix.de In-Reply-To: <20120607131542.GE4759@dhcp-26-207.brq.redhat.com> References: <20120607131542.GE4759@dhcp-26-207.brq.redhat.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/apic] x86/apic: Avoid useless scanning thru a cpumask in assign_irq_vector() Git-Commit-ID: 8637e38aff14d048b649075114023023a2e80fba X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.6 (terminus.zytor.com [127.0.0.1]); Fri, 08 Jun 2012 07:51:10 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4636 Lines: 125 Commit-ID: 8637e38aff14d048b649075114023023a2e80fba Gitweb: http://git.kernel.org/tip/8637e38aff14d048b649075114023023a2e80fba Author: Alexander Gordeev AuthorDate: Thu, 7 Jun 2012 15:15:44 +0200 Committer: Ingo Molnar CommitDate: Fri, 8 Jun 2012 11:44:29 +0200 x86/apic: Avoid useless scanning thru a cpumask in assign_irq_vector() In case of static vector allocation domains (i.e. flat) if all vector numbers are exhausted, an attempt to assign a new vector will lead to useless scans through all CPUs in the cpumask, even though it is known that each new pass would fail. Make this corner case less painful by letting report whether the vector allocation domain depends on passed arguments or not and stop scanning early. The same could have been achived by introducing a static flag to the apic operations. But let's allow vector_allocation_domain() have more intelligence here and decide dynamically, in case we would need it in the future. Signed-off-by: Alexander Gordeev Acked-by: Suresh Siddha Cc: Yinghai Lu Link: http://lkml.kernel.org/r/20120607131542.GE4759@dhcp-26-207.brq.redhat.com Signed-off-by: Ingo Molnar --- arch/x86/include/asm/apic.h | 8 +++++--- arch/x86/kernel/apic/apic_noop.c | 3 ++- arch/x86/kernel/apic/io_apic.c | 12 +++++++++--- 3 files changed, 16 insertions(+), 7 deletions(-) diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h index feb2dbd..e3fecd5 100644 --- a/arch/x86/include/asm/apic.h +++ b/arch/x86/include/asm/apic.h @@ -306,7 +306,7 @@ struct apic { unsigned long (*check_apicid_used)(physid_mask_t *map, int apicid); unsigned long (*check_apicid_present)(int apicid); - void (*vector_allocation_domain)(int cpu, struct cpumask *retmask); + bool (*vector_allocation_domain)(int cpu, struct cpumask *retmask); void (*init_apic_ldr)(void); void (*ioapic_phys_id_map)(physid_mask_t *phys_map, physid_mask_t *retmap); @@ -615,7 +615,7 @@ extern unsigned int default_cpu_mask_to_apicid_and(const struct cpumask *cpumask, const struct cpumask *andmask); -static inline void +static inline bool flat_vector_allocation_domain(int cpu, struct cpumask *retmask) { /* Careful. Some cpus do not strictly honor the set of cpus @@ -628,12 +628,14 @@ flat_vector_allocation_domain(int cpu, struct cpumask *retmask) */ cpumask_clear(retmask); cpumask_bits(retmask)[0] = APIC_ALL_CPUS; + return false; } -static inline void +static inline bool default_vector_allocation_domain(int cpu, struct cpumask *retmask) { cpumask_copy(retmask, cpumask_of(cpu)); + return true; } static inline unsigned long default_check_apicid_used(physid_mask_t *map, int apicid) diff --git a/arch/x86/kernel/apic/apic_noop.c b/arch/x86/kernel/apic/apic_noop.c index 3e43cf5..ac9edf2 100644 --- a/arch/x86/kernel/apic/apic_noop.c +++ b/arch/x86/kernel/apic/apic_noop.c @@ -100,11 +100,12 @@ static unsigned long noop_check_apicid_present(int bit) return physid_isset(bit, phys_cpu_present_map); } -static void noop_vector_allocation_domain(int cpu, struct cpumask *retmask) +static bool noop_vector_allocation_domain(int cpu, struct cpumask *retmask) { if (cpu != 0) pr_warning("APIC: Vector allocated for non-BSP cpu\n"); cpumask_copy(retmask, cpumask_of(cpu)); + return true; } static u32 noop_apic_read(u32 reg) diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c index 05af3d3..4061a7d 100644 --- a/arch/x86/kernel/apic/io_apic.c +++ b/arch/x86/kernel/apic/io_apic.c @@ -1137,8 +1137,9 @@ __assign_irq_vector(int irq, struct irq_cfg *cfg, const struct cpumask *mask) for_each_cpu_and(cpu, mask, cpu_online_mask) { int new_cpu; int vector, offset; + bool more_domains; - apic->vector_allocation_domain(cpu, tmp_mask); + more_domains = apic->vector_allocation_domain(cpu, tmp_mask); if (cpumask_subset(tmp_mask, cfg->domain)) { free_cpumask_var(tmp_mask); @@ -1153,8 +1154,13 @@ next: offset = (offset + 1) % 16; vector = FIRST_EXTERNAL_VECTOR + offset; } - if (unlikely(current_vector == vector)) - continue; + + if (unlikely(current_vector == vector)) { + if (more_domains) + continue; + else + break; + } if (test_bit(vector, used_vectors)) goto next; -- 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/