From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49056) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eMfCF-0000VA-QY for qemu-devel@nongnu.org; Wed, 06 Dec 2017 14:17:35 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eMfCC-0000OF-JO for qemu-devel@nongnu.org; Wed, 06 Dec 2017 14:17:31 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:34372) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eMfCC-0000NO-Bb for qemu-devel@nongnu.org; Wed, 06 Dec 2017 14:17:28 -0500 Received: from pps.filterd (m0098409.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id vB6JGsAd000985 for ; Wed, 6 Dec 2017 14:17:27 -0500 Received: from e13.ny.us.ibm.com (e13.ny.us.ibm.com [129.33.205.203]) by mx0a-001b2d01.pphosted.com with ESMTP id 2epmh3e32t-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 06 Dec 2017 14:17:27 -0500 Received: from localhost by e13.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 6 Dec 2017 14:17:25 -0500 From: Michael Roth Date: Wed, 6 Dec 2017 13:16:16 -0600 In-Reply-To: <20171206191648.18208-1-mdroth@linux.vnet.ibm.com> References: <20171206191648.18208-1-mdroth@linux.vnet.ibm.com> Message-Id: <20171206191648.18208-24-mdroth@linux.vnet.ibm.com> Subject: [Qemu-devel] [PATCH 23/55] memory: seek FlatView sharing candidates among children subregions List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Paolo Bonzini From: Paolo Bonzini A container can be used instead of an alias to allow switching between multiple subregions. In this case we cannot directly share the subregions (since they only belong to a single parent), but if the subregions are aliases we can in turn walk those. This is not enough to remove all source of quadratic FlatView creation, but it enables sharing of the PCI bus master FlatViews (and their AddressSpaceDispatch structures) across all PCI devices. For 112 virtio-net-pci devices, boot time is reduced from 25 to 10 seconds and memory consumption from 1.4 to 1 G. Signed-off-by: Paolo Bonzini (cherry picked from commit e673ba9af9bf8fd8e0f44025ac738b8285b3ed27) Signed-off-by: Michael Roth --- memory.c | 40 ++++++++++++++++++++++++++++++++++------ 1 file changed, 34 insertions(+), 6 deletions(-) diff --git a/memory.c b/memory.c index 774a17f60a..231bb78fa7 100644 --- a/memory.c +++ b/memory.c @@ -733,12 +733,40 @@ static void render_memory_region(FlatView *view, static MemoryRegion *memory_region_get_flatview_root(MemoryRegion *mr) { - while (mr->alias && !mr->alias_offset && - int128_ge(mr->size, mr->alias->size)) { - /* The alias is included in its entirety. Use it as - * the "real" root, so that we can share more FlatViews. - */ - mr = mr->alias; + while (mr->enabled) { + if (mr->alias) { + if (!mr->alias_offset && int128_ge(mr->size, mr->alias->size)) { + /* The alias is included in its entirety. Use it as + * the "real" root, so that we can share more FlatViews. + */ + mr = mr->alias; + continue; + } + } else if (!mr->terminates) { + unsigned int found = 0; + MemoryRegion *child, *next = NULL; + QTAILQ_FOREACH(child, &mr->subregions, subregions_link) { + if (child->enabled) { + if (++found > 1) { + next = NULL; + break; + } + if (!child->addr && int128_ge(mr->size, child->size)) { + /* A child is included in its entirety. If it's the only + * enabled one, use it in the hope of finding an alias down the + * way. This will also let us share FlatViews. + */ + next = child; + } + } + } + if (next) { + mr = next; + continue; + } + } + + break; } return mr; -- 2.11.0