From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f200.google.com (mail-pg1-f200.google.com [209.85.215.200]) (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 9BA01374A12 for ; Fri, 31 Jul 2026 19:56:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.200 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785527781; cv=none; b=LB8ZAo6ZYc/05az8pIq9WZriQ5ruLchRDft1e03ovutzEf28D3blCi7V22RVU3Z+aB6ZBlqVnXWGKdjbG9waFXinBxCFx7xkaaixf8vSZXu+mPAACCHDsC+PwHkCFxlGOu2HZAINlcziSMGC8jH0iorz0lQatt8YJs1HIVz+QUI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785527781; c=relaxed/simple; bh=GTCdXxGxuqpPISX7zn1bGR9hfy0DxUEEavsRgWp0XqI=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=aInCc5Db5R9BF2nqMYNGGHCGk+fQsHGEgcyxUqnvvzhlHTDWzpEc+OWsIDrkht2VkW4HVkPxFyZ3RQyJQGabNJqR35Tb1pIdsW9jD5TvsHml1UiJ28TpQNQ1e+ZDONlpyORIrp9zonvT6MlOhcpUWg7jHaLWI0OoF+TzYWPokXM= 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=Liey1uSx; arc=none smtp.client-ip=209.85.215.200 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="Liey1uSx" Received: by mail-pg1-f200.google.com with SMTP id 41be03b00d2f7-cb48f41343aso1722038a12.1 for ; Fri, 31 Jul 2026 12:56:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1785527779; x=1786132579; 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=Liey1uSxpfKCH6JZeLyUxzZ7+n64L7Ns6lCIr+nI/s9trFUIhi1tXdbG20rGJuIAR+ aW3TNt+JPMbwTLAAbvdx9qYUmoCNZHq1j1SiJQdHmq2CUGvYolGipBGyb5VyKF1qKk2m RS9wRTbFHRRhYtL/JYb0Tcb5u3VJhuTy9mvptfv74a1t/HlpnVr14YBL+qkH0juXzEk4 jxwICG+b9SupYtrxv7whoPRRjulpTaRzuZCOtaynoovSWv3pJ6ZvWf3T5NhUCRkgmngb ZAmX40ckyns3VTONZKYsb6Nrq+5SLqNHuc1rdFWBgIWosQFVwwZlCDa4ZfTm6f1i5qnD vTDQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1785527779; x=1786132579; 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=Ch4Q8F/2gjomLRiaLLufU0nMjXIjgt2SgYx/jeqZK+2YdIAxvOJXdsIXLwT6bh7VTU K7Qgc8VJCDyjuuoyljZACxZ8q8lLuqX7utkbqifKbfCI93ep7vPBnpwHxSn02LAOH3Nj 6D9+SKmI5lj56LxY+CV0KaE4GY8Rug9Bu1Mpo6mQqgdHmWmIzF0ClA0ApsYI1BEZ6y6Q Ggsc+QZV4HCGqR1qb/YRi+EiT6zo3Taze4xfTeRF/Azb3kn3rwJYpm+TjCSqyh+j/Z63 jcTkuwPfQOVIK+OQGJM8rvdHUz8pFcVpZhxhquRhagHJIJEwZOvchXTi7iEq8MpmREFY Id8A== X-Forwarded-Encrypted: i=1; AHgh+Rqo5V6MZfklFqDgIIkZY159mmibiH05DjjquiBY7UIfJnIpjGhmZ8tv3YZoOfXbsjHQr84=@vger.kernel.org X-Gm-Message-State: AOJu0YysLKWripP26GIuK7ypXLWHm6UedydT9bo+r3RWvl0+kELfoIq7 mzvkCKSHanZaH4dyAq/fAnstr9tZmSow0YFX+V6hoDTrdFdJsZdjtbn+JThXj8U5VQlD1c+o7Al 3Atj3Qw== X-Received: from pgj184.prod.google.com ([2002:a63:9c1:0:b0:c99:aff5:7078]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a20:7290:b0:3bf:651d:fee0 with SMTP id adf61e73a8af0-3c92ae1d81fmr774604637.19.1785527778610; Fri, 31 Jul 2026 12:56:18 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 31 Jul 2026 12:56:02 -0700 In-Reply-To: <20260731195612.2697986-1-seanjc@google.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260731195612.2697986-1-seanjc@google.com> X-Mailer: git-send-email 2.55.0.508.g3f0d502094-goog Message-ID: <20260731195612.2697986-3-seanjc@google.com> Subject: [PATCH v3 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