Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933977Ab2FELYh (ORCPT ); Tue, 5 Jun 2012 07:24:37 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55803 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761870Ab2FELYf (ORCPT ); Tue, 5 Jun 2012 07:24:35 -0400 Date: Tue, 5 Jun 2012 13:24:29 +0200 From: Alexander Gordeev To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, Suresh Siddha , Yinghai Lu Subject: [PATCH 6/8] x86: apic: Avoid useless scanning thru a cpumask in assign_irq_vector() Message-ID: <20120605112422.GA11473@dhcp-26-207.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4077 Lines: 119 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 --- 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 9571160..011e9d4 100644 --- a/arch/x86/include/asm/apic.h +++ b/arch/x86/include/asm/apic.h @@ -301,7 +301,7 @@ 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); @@ -598,7 +598,7 @@ 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 @@ -611,12 +611,14 @@ 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 4cc0b77..e8c6e9c 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 f043d6a..f80321e 100644 --- a/arch/x86/kernel/apic/io_apic.c +++ b/arch/x86/kernel/apic/io_apic.c @@ -1189,8 +1189,9 @@ __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); vector = current_vector; offset = current_offset; @@ -1200,8 +1201,13 @@ 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; -- 1.7.7.6 -- Regards, Alexander Gordeev agordeev@redhat.com -- 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/