From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 025257E for ; Wed, 19 Oct 2022 00:26:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1666139191; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=2iRn13iSXiKN1tasBVGZtH8JeAlfEonkeX/dLbbng1k=; b=iUhRaShlmmIdSVo9an2mkZi+zFcstqJzBUhpMZ8J7g0fDvQkWhRIoDOszcTtZ/4rI7HKQF iU8s5EgqjwJuw1wcF8CzrEWzUBuGIRalbolOneMsyOWyfEN94XDNBN88dUbvMtnE0/N8gb edbgnQ/u/Ndw2Teaubt8RP1gP+Nfgac= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-141-y8oaFLu7N5emg5q9o1-lYw-1; Tue, 18 Oct 2022 20:26:28 -0400 X-MC-Unique: y8oaFLu7N5emg5q9o1-lYw-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id C8A1F3C01E0A; Wed, 19 Oct 2022 00:26:27 +0000 (UTC) Received: from [10.64.54.70] (vpn2-54-70.bne.redhat.com [10.64.54.70]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 506502028DC1; Wed, 19 Oct 2022 00:26:22 +0000 (UTC) Reply-To: Gavin Shan Subject: Re: [PATCH 4/6] KVM: selftests: memslot_perf_test: Support variable guest page size To: "Maciej S. Szmigiero" Cc: kvm@vger.kernel.org, maz@kernel.org, linux-kernel@vger.kernel.org, zhenyzha@redhat.com, shan.gavin@gmail.com, kvmarm@lists.linux.dev, pbonzini@redhat.com, shuah@kernel.org, kvmarm@lists.cs.columbia.edu, ajones@ventanamicro.com References: <20221014071914.227134-1-gshan@redhat.com> <20221014071914.227134-5-gshan@redhat.com> <3eecebca-a526-d10a-02d3-496ce919d577@maciej.szmigiero.name> From: Gavin Shan Message-ID: <5bfbe050-a654-8400-e1f1-dcfa4dba13e6@redhat.com> Date: Wed, 19 Oct 2022 08:26:19 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.0 Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 Message-ID: <20221019002619.BrxBLKQi2wmvw4a_P99EMY7fMDCeYhHJb7WjM6eJaOw@z> On 10/18/22 11:56 PM, Maciej S. Szmigiero wrote: > On 18.10.2022 02:51, Gavin Shan wrote: >> On 10/18/22 8:46 AM, Gavin Shan wrote: >>> On 10/18/22 5:31 AM, Maciej S. Szmigiero wrote: >>>> On 14.10.2022 09:19, Gavin Shan wrote: >>>>> The test case is obviously broken on aarch64 because non-4KB guest >>>>> page size is supported. The guest page size on aarch64 could be 4KB, >>>>> 16KB or 64KB. >>>>> >>>>> This supports variable guest page size, mostly for aarch64. >>>>> >>>>>    - The host determines the guest page size when virtual machine is >>>>>      created. The value is also passed to guest through the synchronization >>>>>      area. >>>>> >>>>>    - The number of guest pages are unknown until the virtual machine >>>>>      is to be created. So all the related macros are dropped. Instead, >>>>>      their values are dynamically calculated based on the guest page >>>>>      size. >>>>> >>>>>    - The static checks on memory sizes and pages becomes dependent >>>>>      on guest page size, which is unknown until the virtual machine >>>>>      is about to be created. So all the static checks are converted >>>>>      to dynamic checks, done in check_memory_sizes(). >>>>> >>>>>    - As the address passed to madvise() should be aligned to host page, >>>>>      the size of page chunk is automatically selected, other than one >>>>>      page. >>>>> >>>>>    - All other changes included in this patch are almost mechanical >>>>>      replacing '4096' with 'guest_page_size'. >>>>> >>>>> Signed-off-by: Gavin Shan >>>>> --- >>>>>   .../testing/selftests/kvm/memslot_perf_test.c | 191 +++++++++++------- >>>>>   1 file changed, 115 insertions(+), 76 deletions(-) >>>>> >>>>> diff --git a/tools/testing/selftests/kvm/memslot_perf_test.c b/tools/testing/selftests/kvm/memslot_perf_test.c >>>>> index d5aa9148f96f..d587bd952ff9 100644 >>>>> --- a/tools/testing/selftests/kvm/memslot_perf_test.c >>>>> +++ b/tools/testing/selftests/kvm/memslot_perf_test.c > (...) >>>>> @@ -77,8 +61,7 @@ static_assert(MEM_TEST_UNMAP_SIZE_PAGES % >>>>>    * for the total size of 25 pages. >>>>>    * Hence, the maximum size here is 50 pages. >>>>>    */ >>>>> -#define MEM_TEST_MOVE_SIZE_PAGES    (50) >>>>> -#define MEM_TEST_MOVE_SIZE        (MEM_TEST_MOVE_SIZE_PAGES * 4096) >>>>> +#define MEM_TEST_MOVE_SIZE        0x32000 >>>> >>>> The above number seems less readable than an explicit value of 50 pages. >>>> >>>> In addition to that, it's 50 pages only with 4k page size, so at least >>>> the comment above needs to be updated to reflect this fact. >>>> >>> >>> Yeah, I will change the comments like below in next revision. >>> >>>   /* >>>    * When running this test with 32k memslots, actually 32763 excluding >>>    * the reserved memory slot 0, the memory for each slot is 0x4000 bytes. >>>    * The last slot contains 0x19000 bytes memory. Hence, the maximum size >>>    * here is 0x32000 bytes. >>>    */ >>> >> >> I will replace those numbers with readable ones like below :) >> >> /* >>   * When running this test with 32k memslots, actually 32763 excluding >>   * the reserved memory slot 0, the memory for each slot is 16KB. The >>   * last slot contains 100KB memory with the remaining 84KB. Hence, >>   * the maximum size is double of that (200KB) >>   */ > > Still, these numbers are for x86, which has KVM_INTERNAL_MEM_SLOTS > defined as 3. > > As far as I can see aarch64 has KVM_INTERNAL_MEM_SLOTS equal to 0, so > this arch has 32766 slot available for the test memory. > > Quick calculations show that this will result in 112 KiB of memory in > the last slot for 4 KiB page size (while for 64 KiB page size the > maximum slot count for this test is 8192 anyway - not counting slot 0). > It seems your calculation had (512MB+64KB), instead of (512MB+4KB). In this particular patch, we still have (512MB+4KB). How about to change like below in this patch. In next patch, it's adjusted accordingly after we have (512MB+64KB). (1) In this patch, the comment is changed to as below /* * We have different number of memory slots, excluding the reserved * memory slot 0, on various architectures and configurations. The * memory size in this test is calculated by doubling the maximal * memory size in last memory slot, with alignment to the largest * supported page size (64KB). * * architecture slots memory-per-slot memory-on-last-slot * -------------------------------------------------------------- * x86-4KB 32763 16KB 100KB * arm64-4KB 32766 16KB 52KB * arm64-64KB 8192 64KB 64KB */ #define MEM_TEST_MOVE_SIZE 0x40000 /* 256KB */ (2) In the next patch, where we have (512MB+64KB) after the various memory sizes are consolidated, It is adjusted accordingly as below. /* * We have different number of memory slots, excluding the reserved * memory slot 0, on various architectures and configurations. The * memory size in this test is calculated by doubling the maximal * memory size in last memory slot, with alignment to the largest * supported page size (64KB). * * architecture slots memory-per-slot memory-on-last-slot * -------------------------------------------------------------- * x86-4KB 32763 16KB 160KB * arm64-4KB 32766 16KB 112KB * arm64-64KB 8192 64KB 128KB */ #define MEM_TEST_MOVE_SIZE 0x50000 /* 320KB */ Thanks, Gavin