From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f198.google.com (mail-pf1-f198.google.com [209.85.210.198]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0C24644A724 for ; Fri, 31 Jul 2026 17:06:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.198 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785517587; cv=none; b=CHHiaMy2T26RbMUwzvLXD3cKM2CgY629gciKIfSaRuCO715u3PiM1a0bQoapudJkA/ModIjQ+oLQ9pGl7+IM0yjMnSvKkK3WDZ3EqR/xLNa+dH86l+4NIve5NFi0r+xMNub2SXEL1lZGarm/6fFGjkDnsMdXJIDFFmLANtehbqE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785517587; c=relaxed/simple; bh=GTCdXxGxuqpPISX7zn1bGR9hfy0DxUEEavsRgWp0XqI=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=PElys/uO+4bv6vaMrDCaXO6g6BC/eV/Z2B+Zrd+UMeXIZtgWm4cks5WQYnlRmoLqJmmojJO/KNFXj1ehjGJntJeEoo8oZQvRCPeaEMp1dzqXGFWlZqKgRjXAidxkIlHMs/fSsfFSWz8frGeqZXLTCIUoeRV2zzcxNJAAzs0q8q4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=Rs9Rnfg7; arc=none smtp.client-ip=209.85.210.198 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="Rs9Rnfg7" Received: by mail-pf1-f198.google.com with SMTP id d2e1a72fcca58-84865f326efso1150882b3a.0 for ; Fri, 31 Jul 2026 10:06:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1785517585; x=1786122385; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:reply-to:from:to:cc:subject:date:message-id :reply-to:content-type; bh=6tcAvkg/zKE4Wpx2bpF+dHLf7/L283ci232zJUD1488=; b=Rs9Rnfg7RzSq+qrx8RERN7AEsRVaK4eY60eLDpSQBGI3eoCwcvK2IV3XmhgTnFZjwF l8a52dbF9sSYpdur+qYuVAS/ECoSDcE51wpSbriJDUB//AOH+GSJhUsaQnuYPrLOHNJw UrSX7KYiQYwVJxrLsunK7jYI4IlzCHgEC3q2EIe2zcwosfla87e0Jpbbj6mVqeWSDTaq Lb0JXSFU+7prz6dZqBINjV4k2T/+qTJ+6JkCmHym9yA5v+RK2sWIKoAKkGaothKrO7if 9BrzUW9mqQ6lzrJkua4vx7TW00V/f2AJZx+882MTqDKldTunSa6K7oDp9pwDni1llG6X Zewg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1785517585; x=1786122385; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:reply-to:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to:content-type; bh=6tcAvkg/zKE4Wpx2bpF+dHLf7/L283ci232zJUD1488=; b=mOFAnHbcnG71tZmW1E6LBAaYTHvUXJSUlWWDnwEDtzO3eZWzg5Mcu4l0z9/2xTHlqH BaaZuuG4CEZjDIOdkGYAC/oBGqUvZ30jsyYw3C5Al6hnyph2CuW5a710JdBgtQWiM2qP 7pPJeYYMtYKx/NUvpwLcf2Tzm64t7XHyRZZb0UMtBal6BPXbwJgzahjA3F0c/4NmEXiZ WmW8PRnfLQBbbkP0yCQt8zEBbkqvKFLdK5i67Qw1NL80/ZF7/A16+XRPlV8tnAPcONJ3 LhyJwozcTrmha7Ecc1G2t8LuApv+QFlxvDbVcxQAUybAzPNG+M+fK4K8K+Fwi2/I5SD9 HCUQ== X-Forwarded-Encrypted: i=1; AHgh+RrxU7b2r0uZPXCWfBUIa6Qe/bJ/Vh1Yfr5xAwOyIJUM20mz98AqWqTYIMgr8s54mZUN7aQ=@vger.kernel.org X-Gm-Message-State: AOJu0YyJXoda69xNLx8OmEAKItJa+ZywMJUneqmgCEOR+xhvIWA47tVz V6qbYyQSxJ1dXu8iaXv2z7WLLLQ37VEcFXiKwdtIIU/oaZbDeivMOngzrTwdtBDe9ivXm55MFtz r/XxjJQ== X-Received: from pfnu15.prod.google.com ([2002:aa7:848f:0:b0:847:8962:8101]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:a909:b0:84e:1815:f999 with SMTP id d2e1a72fcca58-84ee4998f39mr357940b3a.64.1785517585158; Fri, 31 Jul 2026 10:06:25 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 31 Jul 2026 10:06:09 -0700 In-Reply-To: <20260731170619.2620845-1-seanjc@google.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260731170619.2620845-1-seanjc@google.com> X-Mailer: git-send-email 2.55.0.508.g3f0d502094-goog Message-ID: <20260731170619.2620845-3-seanjc@google.com> Subject: [PATCH v2 02/12] KVM: selftests: Set threads CPU affinity before doing work in hardware disable test From: Sean Christopherson To: Paolo Bonzini , Marc Zyngier , Oliver Upton , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Sean Christopherson Cc: Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , David Hildenbrand , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Affine worker threads to their target pCPU set *before* doing any work in the hardware disable test. When running a preemptible kernel on a NUMA system with a large number of CPUs (100+ of CPUs), waiting to set the affinity of the grandchildren until after the grandchild is fully spun up results in total test runtimes of over a minute, presumably due to cross-node NUMA penalties and scheduler lock contention. E.g. from the perspective of the caller, when waiting to affine the tasks, pthread_create() takes ~100x longer. Signed-off-by: Sean Christopherson --- .../selftests/kvm/hardware_disable_test.c | 23 +++++++------------ 1 file changed, 8 insertions(+), 15 deletions(-) diff --git a/tools/testing/selftests/kvm/hardware_disable_test.c b/tools/testing/selftests/kvm/hardware_disable_test.c index 3147f5c97e94..f088b4af3ccc 100644 --- a/tools/testing/selftests/kvm/hardware_disable_test.c +++ b/tools/testing/selftests/kvm/hardware_disable_test.c @@ -21,6 +21,7 @@ #define FORK_NUM (1ULL << 9) #define DELAY_US_MAX 2000 +static cpu_set_t threads_cpu_set; sem_t *sem; static void guest_code(void) @@ -35,6 +36,8 @@ static void *run_vcpu(void *arg) struct kvm_vcpu *vcpu = arg; struct kvm_run *run = vcpu->run; + kvm_sched_setaffinity(0, sizeof(cpu_set_t), &threads_cpu_set); + vcpu_run(vcpu); TEST_ASSERT(false, "%s: exited with reason %d: %s", @@ -47,6 +50,8 @@ static void *sleeping_thread(void *arg) { int fd; + kvm_sched_setaffinity(0, sizeof(cpu_set_t), &threads_cpu_set); + while (true) { fd = open("/dev/null", O_RDWR); close(fd); @@ -64,14 +69,6 @@ static inline void check_create_thread(pthread_t *thread, pthread_attr_t *attr, TEST_ASSERT(r == 0, "%s: failed to create thread", __func__); } -static inline void check_set_affinity(pthread_t thread, cpu_set_t *cpu_set) -{ - int r; - - r = pthread_setaffinity_np(thread, sizeof(cpu_set_t), cpu_set); - TEST_ASSERT(r == 0, "%s: failed set affinity", __func__); -} - static inline void check_join(pthread_t thread, void **retval) { int r; @@ -84,16 +81,11 @@ static void run_test(u32 run) { struct kvm_vcpu *vcpu; struct kvm_vm *vm; - cpu_set_t cpu_set; pthread_t threads[VCPU_NUM]; pthread_t throw_away; void *b; u32 i, j; - CPU_ZERO(&cpu_set); - for (i = 0; i < VCPU_NUM; i++) - CPU_SET(i, &cpu_set); - vm = vm_create(VCPU_NUM); pr_debug("%s: [%d] start vcpus\n", __func__, run); @@ -101,12 +93,10 @@ static void run_test(u32 run) vcpu = vm_vcpu_add(vm, i, guest_code); check_create_thread(&threads[i], NULL, run_vcpu, vcpu); - check_set_affinity(threads[i], &cpu_set); for (j = 0; j < SLEEPING_THREAD_NUM; ++j) { check_create_thread(&throw_away, NULL, sleeping_thread, (void *)NULL); - check_set_affinity(throw_away, &cpu_set); } } pr_debug("%s: [%d] all threads launched\n", __func__, run); @@ -153,6 +143,9 @@ int main(int argc, char **argv) int s, r; pid_t pid; + for (i = 0; i < VCPU_NUM; i++) + CPU_SET(i, &threads_cpu_set); + sem = sem_open("vm_sem", O_CREAT | O_EXCL, 0644, 0); sem_unlink("vm_sem"); -- 2.55.0.508.g3f0d502094-goog