From nobody Tue Nov 18 07:47:37 2025 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org ARC-Seal: i=1; a=rsa-sha256; t=1608016958; cv=none; d=zohomail.com; s=zohoarc; b=dDkAka8YsFs7k0loaqjt8JE/IZId/ELGcHGVwk+5Gd4IvTwoa1+lRsA04BZHrYqYChdCYQq1h1CNAhay6NSSPjTFJsVB5rVD6QWps4Hu3vVShcwv7i7zfwVMJDuNcN4cBNu8vm99LJhObnbRR8cn6OJ3ImeKbUgiIsadkK753Ps= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1608016958; h=Content-Type:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=rzCMsEHWgO0MTcOVns4RRsRvZuV2JA7oXLeih/WVwus=; b=Xrk7KudNfIhogfPJKXSn7OiTxg11vq+D5flBFaLUk+rkU/Tox+gg+Eqohje7u7wNT4ryDtG7abYOB4PbGKm413p3t7hnEQiP/hKBTqU8EFEi4uKJvirad4CC1Jm03GY2mBdG0U7SCLg+7+DDkFhZtb6gK7DD264903uDNOVWmOM= ARC-Authentication-Results: i=1; mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1608016958458457.0128054434307; Mon, 14 Dec 2020 23:22:38 -0800 (PST) Received: from localhost ([::1]:34302 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kp4fN-0002ZF-1z for importer@patchew.org; Tue, 15 Dec 2020 02:22:37 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:57164) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kp4dH-0001N5-Li; Tue, 15 Dec 2020 02:20:29 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:2891) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kp4d8-0008R9-El; Tue, 15 Dec 2020 02:20:27 -0500 Received: from DGGEMS414-HUB.china.huawei.com (unknown [172.30.72.58]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4Cw8lL4nTgz15f1g; Tue, 15 Dec 2020 15:19:26 +0800 (CST) Received: from DESKTOP-5IS4806.china.huawei.com (10.174.187.37) by DGGEMS414-HUB.china.huawei.com (10.3.19.214) with Microsoft SMTP Server id 14.3.498.0; Tue, 15 Dec 2020 15:19:56 +0800 From: Keqian Zhu To: Peter Maydell , Paolo Bonzini , "Dr . David Alan Gilbert" , "Peter Xu" Subject: [PATCH 1/2] accel: kvm: Fix memory waste under mismatch page size Date: Tue, 15 Dec 2020 15:19:47 +0800 Message-ID: <20201215071948.23940-2-zhukeqian1@huawei.com> X-Mailer: git-send-email 2.8.4.windows.1 In-Reply-To: <20201215071948.23940-1-zhukeqian1@huawei.com> References: <20201215071948.23940-1-zhukeqian1@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.174.187.37] X-CFilter-Loop: Reflected Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=45.249.212.190; envelope-from=zhukeqian1@huawei.com; helo=szxga04-in.huawei.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: jiangkunkun@huawei.com, qemu-devel@nongnu.org, qemu-arm@nongnu.org, Zenghui Yu , wanghaibin.wang@huawei.com, Keqian Zhu Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" When handle dirty log, we face qemu_real_host_page_size and TARGET_PAGE_SIZE. The first one is the granule of KVM dirty bitmap, and the second one is the granule of QEMU dirty bitmap. Generally speaking, qemu_real_host_page_size >=3D TARGET_PAGE_SIZE, so misuse TARGET_PAGE_SIZE to init kvmslot dirty_bmap may waste memory. For example, when qemu_real_host_page_size is 64K and TARGET_PAGE_SIZE is 4K, this bugfix can save 93.75% memory. Signed-off-by: Keqian Zhu Reviewed-by: Andrew Jones Reviewed-by: Peter Xu --- accel/kvm/kvm-all.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c index baaa54249d..c5e06288eb 100644 --- a/accel/kvm/kvm-all.c +++ b/accel/kvm/kvm-all.c @@ -620,8 +620,12 @@ static void kvm_memslot_init_dirty_bitmap(KVMSlot *mem) * too, in most cases). * So for now, let's align to 64 instead of HOST_LONG_BITS here, in * a hope that sizeof(long) won't become >8 any time soon. + * + * Note: the granule of kvm dirty log is qemu_real_host_page_size. + * And mem->memory_size is aligned to it (otherwise this mem can't + * be registered to KVM). */ - hwaddr bitmap_size =3D ALIGN(((mem->memory_size) >> TARGET_PAGE_BITS), + hwaddr bitmap_size =3D ALIGN(mem->memory_size / qemu_real_host_page_si= ze, /*HOST_LONG_BITS*/ 64) / 8; mem->dirty_bmap =3D g_malloc0(bitmap_size); } --=20 2.23.0