From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C163CECAAD1 for ; Thu, 1 Sep 2022 17:45:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235135AbiIARpf (ORCPT ); Thu, 1 Sep 2022 13:45:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34950 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234196AbiIARpD (ORCPT ); Thu, 1 Sep 2022 13:45:03 -0400 Received: from mail-pj1-x1034.google.com (mail-pj1-x1034.google.com [IPv6:2607:f8b0:4864:20::1034]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5F7245C340 for ; Thu, 1 Sep 2022 10:44:00 -0700 (PDT) Received: by mail-pj1-x1034.google.com with SMTP id n65-20020a17090a5ac700b001fbb4fad865so3416960pji.1 for ; Thu, 01 Sep 2022 10:44:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date; bh=+/BCAIqtV+vwVZj2X7fGlHMc4J8edyLbzuoLd9z7kHY=; b=HEp1m2oQCqt0fvoDyhrBnaZ5QPKGmC5Wx4PffhWlY7ZX8wtHF5PqMH271ZItmextUQ oD1US8YYezQhz3jNz7CxxLwVBTOXwleKtoNeHGkMWv2afC6JoUSQjkJjsz+mXhMxdgpg oskpusmu26pPgjdGNwcktErr1Mxb2Rw8kanSHOGpSGWJGbVdciOAIO/DEc/q1oUpLEzn gDJeMeSklQ900X+Ci8t8ugaYBxVIXZXz5anNhts5ikgyqRQ3dyZwdTsEsIwJpRHtJEKS sO6pizZYaANEEkZyAboSAQDMh8I/diT8qarWKkMHTn++bKuiLqcpfHzpBAGLzTfUoxT9 vRhA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date; bh=+/BCAIqtV+vwVZj2X7fGlHMc4J8edyLbzuoLd9z7kHY=; b=NqYbdx16a1bie4OGmPSvFvmnJNq+QodN6C+bLi+Emvc8O7gyTpz7H9BMYL2ZftvI5f +z4UVbd8SrTPR6srAwgrIo6hPbAU0q/GtPShfL0KBituezBRvYILb6nNAOjbbM4yjq2A /RpzU4E5+HSRBmYqm1D5K3H6zK5Xp2lLe/vEhvvtRotQtiPji6IqQYv6QDbucWr6tR5M Qs89zCln8sXTMo/LGJQo2zOhCz+L2vuOMRJ1DkNC8qtRgwUWlEzHKPMSSJb9/yEKh4Jo xZvA7ZMO/vvCnm8M+qPj4t5OoG1ont7wQyQ/yShRpbLzq2WnBpJlUoaxGdBRWfVaHIW6 gUTA== X-Gm-Message-State: ACgBeo3SrvIMDMMLfiNZK3ZwSfEWsc1CjjCDwWS+xG7ka/Gg7TExSXWM JF7DViEdqRDSly4Xo88lHjEjyQ== X-Google-Smtp-Source: AA6agR6e0Bo46n+mGFtxOjZBJW15uwE0+IQNS2TFmEpIKn2Rd9exOYQ1paysAQnDhSIRgCqarL+Y6g== X-Received: by 2002:a17:902:d885:b0:172:868f:188c with SMTP id b5-20020a170902d88500b00172868f188cmr31319346plz.78.1662054239672; Thu, 01 Sep 2022 10:43:59 -0700 (PDT) Received: from google.com (220.181.82.34.bc.googleusercontent.com. [34.82.181.220]) by smtp.gmail.com with ESMTPSA id l22-20020a17090af8d600b001f1acb6c3ebsm3598515pjd.34.2022.09.01.10.43.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 01 Sep 2022 10:43:57 -0700 (PDT) Date: Thu, 1 Sep 2022 10:43:51 -0700 From: Ricardo Koller To: Colton Lewis Cc: kvm@vger.kernel.org, pbonzini@redhat.com, maz@kernel.org, dmatlack@google.com, seanjc@google.com, oupton@google.com Subject: Re: [PATCH v2 3/3] KVM: selftests: Randomize page access order. Message-ID: References: <20220817214146.3285106-1-coltonlewis@google.com> <20220817214146.3285106-4-coltonlewis@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220817214146.3285106-4-coltonlewis@google.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Hey Colton, On Wed, Aug 17, 2022 at 09:41:46PM +0000, Colton Lewis wrote: > Create the ability to randomize page access order with the -a > argument, including the possibility that the same pages may be hit > multiple times during an iteration or not at all. > > Signed-off-by: Colton Lewis > --- > tools/testing/selftests/kvm/dirty_log_perf_test.c | 10 +++++++++- > .../testing/selftests/kvm/include/perf_test_util.h | 2 ++ > tools/testing/selftests/kvm/lib/perf_test_util.c | 13 ++++++++++++- > 3 files changed, 23 insertions(+), 2 deletions(-) > > diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c > index 9226eeea79bc..af9754bda0a4 100644 > --- a/tools/testing/selftests/kvm/dirty_log_perf_test.c > +++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c > @@ -133,6 +133,7 @@ struct test_params { > int slots; > uint32_t write_percent; > uint32_t random_seed; > + bool random_access; > }; > > static void toggle_dirty_logging(struct kvm_vm *vm, int slots, bool enable) > @@ -271,6 +272,9 @@ static void run_test(enum vm_guest_mode mode, void *arg) > pr_info("Enabling dirty logging time: %ld.%.9lds\n\n", > ts_diff.tv_sec, ts_diff.tv_nsec); > > + /* Set random access here, after population phase. */ > + perf_test_set_random_access(vm, p->random_access); > + > while (iteration < p->iterations) { > /* > * Incrementing the iteration number will start the vCPUs > @@ -353,10 +357,11 @@ static void run_test(enum vm_guest_mode mode, void *arg) > static void help(char *name) > { > puts(""); > - printf("usage: %s [-h] [-i iterations] [-p offset] [-g] " > + printf("usage: %s [-h] [-a] [-i iterations] [-p offset] [-g] " > "[-m mode] [-n] [-b vcpu bytes] [-v vcpus] [-o] [-r random seed ] [-s mem type]" > "[-x memslots] [-w percentage]\n", name); > puts(""); > + printf(" -a: access memory randomly rather than in order.\n"); > printf(" -i: specify iteration counts (default: %"PRIu64")\n", > TEST_HOST_LOOP_N); > printf(" -g: Do not enable KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2. This\n" > @@ -413,6 +418,9 @@ int main(int argc, char *argv[]) > > while ((opt = getopt(argc, argv, "eghi:p:m:nb:v:or:s:x:w:")) != -1) { > switch (opt) { > + case 'a': > + p.random_access = true; > + break; > case 'e': > /* 'e' is for evil. */ > run_vcpus_while_disabling_dirty_logging = true; > diff --git a/tools/testing/selftests/kvm/include/perf_test_util.h b/tools/testing/selftests/kvm/include/perf_test_util.h > index 8da4a839c585..237899f3f4fe 100644 > --- a/tools/testing/selftests/kvm/include/perf_test_util.h > +++ b/tools/testing/selftests/kvm/include/perf_test_util.h > @@ -41,6 +41,7 @@ struct perf_test_args { > > /* Run vCPUs in L2 instead of L1, if the architecture supports it. */ > bool nested; > + bool random_access; > > struct perf_test_vcpu_args vcpu_args[KVM_MAX_VCPUS]; > }; > @@ -55,6 +56,7 @@ void perf_test_destroy_vm(struct kvm_vm *vm); > > void perf_test_set_write_percent(struct kvm_vm *vm, uint32_t write_percent); > void perf_test_set_random_seed(struct kvm_vm *vm, uint32_t random_seed); > +void perf_test_set_random_access(struct kvm_vm *vm, bool random_access); > > void perf_test_start_vcpu_threads(int vcpus, void (*vcpu_fn)(struct perf_test_vcpu_args *)); > void perf_test_join_vcpu_threads(int vcpus); > diff --git a/tools/testing/selftests/kvm/lib/perf_test_util.c b/tools/testing/selftests/kvm/lib/perf_test_util.c > index 1a6b69713337..84e442a028c0 100644 > --- a/tools/testing/selftests/kvm/lib/perf_test_util.c > +++ b/tools/testing/selftests/kvm/lib/perf_test_util.c > @@ -48,6 +48,7 @@ void perf_test_guest_code(uint32_t vcpu_idx) > struct perf_test_vcpu_args *vcpu_args = &pta->vcpu_args[vcpu_idx]; > uint64_t gva; > uint64_t pages; > + uint64_t addr; > uint32_t *rnd_arr = (uint32_t *)vcpu_args->random_array; > int i; > > @@ -59,7 +60,11 @@ void perf_test_guest_code(uint32_t vcpu_idx) > > while (true) { > for (i = 0; i < pages; i++) { > - uint64_t addr = gva + (i * pta->guest_page_size); > + if (pta->random_access) > + addr = gva + > + ((rnd_arr[i] % pages) * pta->guest_page_size); > + else > + addr = gva + (i * pta->guest_page_size); > > if (rnd_arr[i] % 100 < pta->write_percent) > *(uint64_t *)addr = 0x0123456789ABCDEF; I think addr and write_percent need two different random numbers. Otherwise, you will end up with a situation where all addresses where (rnd_arr[i] % 100 < pta->write_percent) will get a write (always). Something like this: 012345678 <= address wwwrrrwww 837561249 <= access order I think the best way to fix this is to abstract the random number reading into something like get_next_rand(), and use it twice per iteration. > @@ -271,6 +276,12 @@ void perf_test_set_random_seed(struct kvm_vm *vm, uint32_t random_seed) > sync_global_to_guest(vm, perf_test_args); > } > > +void perf_test_set_random_access(struct kvm_vm *vm, bool random_access) > +{ > + perf_test_args.random_access = random_access; > + sync_global_to_guest(vm, perf_test_args); > +} > + > uint64_t __weak perf_test_nested_pages(int nr_vcpus) > { > return 0; > -- > 2.37.1.595.g718a3a8f04-goog > Thanks, Ricardo