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 X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C2BAEC433E1 for ; Fri, 31 Jul 2020 09:19:24 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 8720622D05 for ; Fri, 31 Jul 2020 09:19:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="bJTt0i+i" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8720622D05 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1k1RBy-0000Wp-9O; Fri, 31 Jul 2020 09:19:06 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1k1RBx-0000Vm-4p for xen-devel@lists.xenproject.org; Fri, 31 Jul 2020 09:19:05 +0000 X-Inumbo-ID: de6814e0-d30e-11ea-8e1f-bc764e2007e4 Received: from us-smtp-1.mimecast.com (unknown [205.139.110.120]) by us1-rack-iad1.inumbo.com (Halon) with ESMTP id de6814e0-d30e-11ea-8e1f-bc764e2007e4; Fri, 31 Jul 2020 09:19:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1596187140; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=nOON8+ajaLpXIcBxCYJ6eMATKXtAWnIlcMGpRLJHnBo=; b=bJTt0i+iPUoecHL6hE6yF2u6x9u/VnocEw77lYLaQeSQ8bQ+VJLfFs84wLWoqDbvlHAHCj xjILaBJeVmtLrchGYQpBeEA4rhve19vwAU4KmfiCJXixltInJfy184Vg9QIkmWuV5suksV c7wfg/ODoXhy2UfPQVf3lkGWXgDfmpA= 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-14-a6wjUmLxO62-OZabls5-1w-1; Fri, 31 Jul 2020 05:18:58 -0400 X-MC-Unique: a6wjUmLxO62-OZabls5-1w-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id DFFD618C63C0; Fri, 31 Jul 2020 09:18:56 +0000 (UTC) Received: from t480s.redhat.com (ovpn-113-22.ams2.redhat.com [10.36.113.22]) by smtp.corp.redhat.com (Postfix) with ESMTP id 919091C92D; Fri, 31 Jul 2020 09:18:55 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Subject: [PATCH RFCv1 3/5] virtio-mem: try to merge "System RAM (virtio_mem)" resources Date: Fri, 31 Jul 2020 11:18:36 +0200 Message-Id: <20200731091838.7490-4-david@redhat.com> In-Reply-To: <20200731091838.7490-1-david@redhat.com> References: <20200731091838.7490-1-david@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: linux-mm@kvack.org, linux-hyperv@vger.kernel.org, David Hildenbrand , xen-devel@lists.xenproject.org, virtualization@lists.linux-foundation.org Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" virtio-mem adds memory in memory block granularity, to be able to remove it in the same granularity again later, and to grow slowly on demand. This, however, results in quite a lot of resources when adding a lot of memory. Resources are effectively stored in a list-based tree. Having a lot of resources not only wastes memory, it also makes traversing that tree more expensive, and makes /proc/iomem explode in size (e.g., requiring kexec-tools to manually merge resources later when e.g., trying to create a kdump header). Before this patch, we get (/proc/iomem) when hotplugging 2G via virtio-mem on x86-64: [...] 100000000-13fffffff : System RAM 140000000-33fffffff : virtio0 140000000-147ffffff : System RAM (virtio_mem) 148000000-14fffffff : System RAM (virtio_mem) 150000000-157ffffff : System RAM (virtio_mem) 158000000-15fffffff : System RAM (virtio_mem) 160000000-167ffffff : System RAM (virtio_mem) 168000000-16fffffff : System RAM (virtio_mem) 170000000-177ffffff : System RAM (virtio_mem) 178000000-17fffffff : System RAM (virtio_mem) 180000000-187ffffff : System RAM (virtio_mem) 188000000-18fffffff : System RAM (virtio_mem) 190000000-197ffffff : System RAM (virtio_mem) 198000000-19fffffff : System RAM (virtio_mem) 1a0000000-1a7ffffff : System RAM (virtio_mem) 1a8000000-1afffffff : System RAM (virtio_mem) 1b0000000-1b7ffffff : System RAM (virtio_mem) 1b8000000-1bfffffff : System RAM (virtio_mem) 3280000000-32ffffffff : PCI Bus 0000:00 With this patch, we get (/proc/iomem): [...] fffc0000-ffffffff : Reserved 100000000-13fffffff : System RAM 140000000-33fffffff : virtio0 140000000-1bfffffff : System RAM (virtio_mem) 3280000000-32ffffffff : PCI Bus 0000:00 Of course, with more hotplugged memory, it gets worse. When unplugging memory blocks again, try_remove_memory() (via offline_and_remove_memory()) will properly split the resource up again. Signed-off-by: David Hildenbrand --- drivers/virtio/virtio_mem.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c index f26f5f64ae822..2396a8d67875e 100644 --- a/drivers/virtio/virtio_mem.c +++ b/drivers/virtio/virtio_mem.c @@ -415,6 +415,7 @@ static int virtio_mem_mb_add(struct virtio_mem *vm, unsigned long mb_id) { const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id); int nid = vm->nid; + int rc; if (nid == NUMA_NO_NODE) nid = memory_add_physaddr_to_nid(addr); @@ -431,8 +432,17 @@ static int virtio_mem_mb_add(struct virtio_mem *vm, unsigned long mb_id) } dev_dbg(&vm->vdev->dev, "adding memory block: %lu\n", mb_id); - return add_memory_driver_managed(nid, addr, memory_block_size_bytes(), - vm->resource_name); + rc = add_memory_driver_managed(nid, addr, memory_block_size_bytes(), + vm->resource_name); + if (!rc) { + /* + * Try to reduce the number of resources by merging them. The + * memory removal path will properly split them up again. + */ + merge_child_mem_resources(vm->parent_resource, + vm->resource_name); + } + return rc; } /* -- 2.26.2