From nobody Mon Feb 9 09:33:32 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=fail; 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; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1627315726778801.4051471665954; Mon, 26 Jul 2021 09:08:46 -0700 (PDT) Received: from localhost ([::1]:41662 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1m839p-0002ei-MW for importer@patchew.org; Mon, 26 Jul 2021 12:08:45 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:36364) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m837A-0005gu-BU for qemu-devel@nongnu.org; Mon, 26 Jul 2021 12:06:00 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:21006) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m8378-00031O-Nz for qemu-devel@nongnu.org; Mon, 26 Jul 2021 12:06:00 -0400 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-245-RXKjzudPP8CZeMuMuBHimw-1; Mon, 26 Jul 2021 12:05:56 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 69DB6100E420; Mon, 26 Jul 2021 16:05:55 +0000 (UTC) Received: from t480s.redhat.com (ovpn-112-199.ams2.redhat.com [10.36.112.199]) by smtp.corp.redhat.com (Postfix) with ESMTP id 509805C1CF; Mon, 26 Jul 2021 16:05:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1627315558; h=from:from: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=QWbJXupkNWTpT6UPSCDGnbzUKlgS5wqFAFc3ha2JxH4=; b=Tg5343JLjp0AHylOMkXCdXZHRTTbjDRNRgdMmXWGbDtwzDpwhMph1/v1mmSIOB6GT7KP4e Mp5vD8JD9MslFY7ojT7yVhoZwZdBH6n9PucAEaIV1mGhm4UATNwB6LDbl5jN4cDStuN8uK MZ2GO3yDG4pFtD0zZpr0/xQTMfi15a8= X-MC-Unique: RXKjzudPP8CZeMuMuBHimw-1 From: David Hildenbrand To: qemu-devel@nongnu.org Subject: [PATCH v3 4/4] softmmu/memory_mapping: optimize for RamDiscardManager sections Date: Mon, 26 Jul 2021 18:03:46 +0200 Message-Id: <20210726160346.109915-5-david@redhat.com> In-Reply-To: <20210726160346.109915-1-david@redhat.com> References: <20210726160346.109915-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=david@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable 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=216.205.24.124; envelope-from=david@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.717, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, 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: Laurent Vivier , Thomas Huth , Eduardo Habkost , "Michael S. Tsirkin" , David Hildenbrand , "Dr . David Alan Gilbert" , Peter Xu , Alex Williamson , Claudio Fontana , Paolo Bonzini , =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= , =?UTF-8?q?Alex=20Benn=C3=A9e?= , Igor Mammedov , Stefan Berger Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) X-ZM-MESSAGEID: 1627315728556100001 virtio-mem logically plugs/unplugs memory within a sparse memory region and notifies via the RamDiscardManager interface when parts become plugged (populated) or unplugged (discarded). Currently, we end up (via the two users) 1) zeroing all logically unplugged/discarded memory during TPM resets. 2) reading all logically unplugged/discarded memory when dumping, to figure out the content is zero. 1) is always bad, because we assume unplugged memory stays discarded (and is already implicitly zero). 2) isn't that bad with anonymous memory, we end up reading the zero page (slow and unnecessary, though). However, once we use some file-backed memory (future use case), even reading will populate memory. Let's cut out all parts marked as not-populated (discarded) via the RamDiscardManager. As virtio-mem is the single user, this now means that logically unplugged memory ranges will no longer be included in the dump, which results in smaller dump files and faster dumping. virtio-mem has a minimum granularity of 1 MiB (and the default is usually 2 MiB). Theoretically, we can see quite some fragmentation, in practice we won't have it completely fragmented in 1 MiB pieces. Still, we might end up with many physical ranges. Both, the ELF format and kdump seem to be ready to support many individual ranges (e.g., for ELF it seems to be UINT32_MAX, kdump has a linear bitmap). Reviewed-by: Peter Xu Cc: Marc-Andr=C3=A9 Lureau Cc: Paolo Bonzini Cc: "Michael S. Tsirkin" Cc: Eduardo Habkost Cc: Alex Williamson Cc: Dr. David Alan Gilbert Cc: Igor Mammedov Cc: Claudio Fontana Cc: Thomas Huth Cc: "Alex Benn=C3=A9e" Cc: Peter Xu Cc: Laurent Vivier Cc: Stefan Berger Signed-off-by: David Hildenbrand --- softmmu/memory_mapping.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/softmmu/memory_mapping.c b/softmmu/memory_mapping.c index a2af02c41c..a62eaa49cc 100644 --- a/softmmu/memory_mapping.c +++ b/softmmu/memory_mapping.c @@ -246,6 +246,15 @@ static void guest_phys_block_add_section(GuestPhysList= ener *g, #endif } =20 +static int guest_phys_ram_populate_cb(MemoryRegionSection *section, + void *opaque) +{ + GuestPhysListener *g =3D opaque; + + guest_phys_block_add_section(g, section); + return 0; +} + static void guest_phys_blocks_region_add(MemoryListener *listener, MemoryRegionSection *section) { @@ -257,6 +266,17 @@ static void guest_phys_blocks_region_add(MemoryListene= r *listener, memory_region_is_nonvolatile(section->mr)) { return; } + + /* for special sparse regions, only add populated parts */ + if (memory_region_has_ram_discard_manager(section->mr)) { + RamDiscardManager *rdm; + + rdm =3D memory_region_get_ram_discard_manager(section->mr); + ram_discard_manager_replay_populated(rdm, section, + guest_phys_ram_populate_cb, g= ); + return; + } + guest_phys_block_add_section(g, section); } =20 --=20 2.31.1