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=-8.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 B0531C43331 for ; Tue, 31 Mar 2020 10:35:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6435320772 for ; Tue, 31 Mar 2020 10:35:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="UCYXL+h1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730217AbgCaKfm (ORCPT ); Tue, 31 Mar 2020 06:35:42 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:44735 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729925AbgCaKfl (ORCPT ); Tue, 31 Mar 2020 06:35:41 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585650939; 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:autocrypt:autocrypt; bh=7Is+kEnWeMwJR4W5Fu2nbZV1wb8zzwSNSK6qUiY612s=; b=UCYXL+h1AHwrcCGqiDrQj9i9YA0DqjQ99ssV9GJh6j0FRMNyrgw3bt6oskCOlNQCSTagje vUOOZkY18/dsuROwfY+sPjYsg+9Dcnu9JJA/W1t2dpybL+AP3sABQJDJNssXuavXw6UogW b0LOsR+KRz284JEiYI4h2xFCdXjToHE= 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-44-aBgsaJtsMUqAA-onkrfTwA-1; Tue, 31 Mar 2020 06:35:38 -0400 X-MC-Unique: aBgsaJtsMUqAA-onkrfTwA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 9550E1937FC1; Tue, 31 Mar 2020 10:35:35 +0000 (UTC) Received: from [10.36.114.0] (ovpn-114-0.ams2.redhat.com [10.36.114.0]) by smtp.corp.redhat.com (Postfix) with ESMTP id 419E660BE2; Tue, 31 Mar 2020 10:35:25 +0000 (UTC) Subject: Re: [RFC for Linux] virtio_balloon: Add VIRTIO_BALLOON_F_THP_ORDER to handle THP spilt issue To: "Michael S. Tsirkin" Cc: Hui Zhu , jasowang@redhat.com, akpm@linux-foundation.org, pagupta@redhat.com, mojha@codeaurora.org, namit@vmware.com, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, qemu-devel@nongnu.org, Hui Zhu , Alexander Duyck References: <20200326031817-mutt-send-email-mst@kernel.org> <20200326054554-mutt-send-email-mst@kernel.org> From: David Hildenbrand Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= mQINBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABtCREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT6JAlgEEwEIAEICGwMFCQlmAYAGCwkIBwMCBhUI AgkKCwQWAgMBAh4BAheAFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl3pImkCGQEACgkQTd4Q 9wD/g1o+VA//SFvIHUAvul05u6wKv/pIR6aICPdpF9EIgEU448g+7FfDgQwcEny1pbEzAmiw zAXIQ9H0NZh96lcq+yDLtONnXk/bEYWHHUA014A1wqcYNRY8RvY1+eVHb0uu0KYQoXkzvu+s Dncuguk470XPnscL27hs8PgOP6QjG4jt75K2LfZ0eAqTOUCZTJxA8A7E9+XTYuU0hs7QVrWJ jQdFxQbRMrYz7uP8KmTK9/Cnvqehgl4EzyRaZppshruKMeyheBgvgJd5On1wWq4ZUV5PFM4x II3QbD3EJfWbaJMR55jI9dMFa+vK7MFz3rhWOkEx/QR959lfdRSTXdxs8V3zDvChcmRVGN8U Vo93d1YNtWnA9w6oCW1dnDZ4kgQZZSBIjp6iHcA08apzh7DPi08jL7M9UQByeYGr8KuR4i6e RZI6xhlZerUScVzn35ONwOC91VdYiQgjemiVLq1WDDZ3B7DIzUZ4RQTOaIWdtXBWb8zWakt/ ztGhsx0e39Gvt3391O1PgcA7ilhvqrBPemJrlb9xSPPRbaNAW39P8ws/UJnzSJqnHMVxbRZC Am4add/SM+OCP0w3xYss1jy9T+XdZa0lhUvJfLy7tNcjVG/sxkBXOaSC24MFPuwnoC9WvCVQ ZBxouph3kqc4Dt5X1EeXVLeba+466P1fe1rC8MbcwDkoUo65Ag0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAGJAiUEGAECAA8FAlXLn5ECGwwFCQlmAYAACgkQTd4Q 9wD/g1qA6w/+M+ggFv+JdVsz5+ZIc6MSyGUozASX+bmIuPeIecc9UsFRatc91LuJCKMkD9Uv GOcWSeFpLrSGRQ1Z7EMzFVU//qVs6uzhsNk0RYMyS0B6oloW3FpyQ+zOVylFWQCzoyyf227y GW8HnXunJSC+4PtlL2AY4yZjAVAPLK2l6mhgClVXTQ/S7cBoTQKP+jvVJOoYkpnFxWE9pn4t H5QIFk7Ip8TKr5k3fXVWk4lnUi9MTF/5L/mWqdyIO1s7cjharQCstfWCzWrVeVctpVoDfJWp 4LwTuQ5yEM2KcPeElLg5fR7WB2zH97oI6/Ko2DlovmfQqXh9xWozQt0iGy5tWzh6I0JrlcxJ ileZWLccC4XKD1037Hy2FLAjzfoWgwBLA6ULu0exOOdIa58H4PsXtkFPrUF980EEibUp0zFz GotRVekFAceUaRvAj7dh76cToeZkfsjAvBVb4COXuhgX6N4pofgNkW2AtgYu1nUsPAo+NftU CxrhjHtLn4QEBpkbErnXQyMjHpIatlYGutVMS91XTQXYydCh5crMPs7hYVsvnmGHIaB9ZMfB njnuI31KBiLUks+paRkHQlFcgS2N3gkRBzH7xSZ+t7Re3jvXdXEzKBbQ+dC3lpJB0wPnyMcX FOTT3aZT7IgePkt5iC/BKBk3hqKteTnJFeVIT7EC+a6YUFg= Organization: Red Hat GmbH Message-ID: Date: Tue, 31 Mar 2020 12:35:24 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20200326054554-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 26.03.20 10:49, Michael S. Tsirkin wrote: > On Thu, Mar 26, 2020 at 08:54:04AM +0100, David Hildenbrand wrote: >> >> >>> Am 26.03.2020 um 08:21 schrieb Michael S. Tsirkin : >>> >>> =EF=BB=BFOn Thu, Mar 12, 2020 at 09:51:25AM +0100, David Hildenbrand = wrote: >>>>> On 12.03.20 09:47, Michael S. Tsirkin wrote: >>>>> On Thu, Mar 12, 2020 at 09:37:32AM +0100, David Hildenbrand wrote: >>>>>> 2. You are essentially stealing THPs in the guest. So the fastest >>>>>> mapping (THP in guest and host) is gone. The guest won't be able t= o make >>>>>> use of THP where it previously was able to. I can imagine this imp= lies a >>>>>> performance degradation for some workloads. This needs a proper >>>>>> performance evaluation. >>>>> >>>>> I think the problem is more with the alloc_pages API. >>>>> That gives you exactly the given order, and if there's >>>>> a larger chunk available, it will split it up. >>>>> >>>>> But for balloon - I suspect lots of other users, >>>>> we do not want to stress the system but if a large >>>>> chunk is available anyway, then we could handle >>>>> that more optimally by getting it all in one go. >>>>> >>>>> >>>>> So if we want to address this, IMHO this calls for a new API. >>>>> Along the lines of >>>>> >>>>> struct page *alloc_page_range(gfp_t gfp, unsigned int min_order, >>>>> unsigned int max_order, unsigned int *order) >>>>> >>>>> the idea would then be to return at a number of pages in the given >>>>> range. >>>>> >>>>> What do you think? Want to try implementing that? >>>> >>>> You can just start with the highest order and decrement the order un= til >>>> your allocation succeeds using alloc_pages(), which would be enough = for >>>> a first version. At least I don't see the immediate need for a new >>>> kernel API. >>> >>> OK I remember now. The problem is with reclaim. Unless reclaim is >>> completely disabled, any of these calls can sleep. After it wakes up, >>> we would like to get the larger order that has become available >>> meanwhile. >>> >> >> Yes, but that=E2=80=98s a pure optimization IMHO. >> So I think we should do a trivial implementation first and then see wh= at we gain from a new allocator API. Then we might also be able to justif= y it using real numbers. >> >=20 > Well how do you propose implement the necessary semantics? > I think we are both agreed that alloc_page_range is more or > less what's necessary anyway - so how would you approximate it > on top of existing APIs? Looking at drivers/misc/vmw_balloon.c:vmballoon_inflate(), it first tries to allocate huge pages using alloc_pages(__GFP_HIGHMEM|__GFP_NOWARN| __GFP_NOMEMALLOC,=20 VMW_BALLOON_2M_ORDER) And then falls back to 4k allocations (balloon_page_alloc()) in case allocation fails. I'm roughly thinking of something like the following, but with an optimized reporting interface/bigger pfn array so we can report > 1MB at a time. Also, it might make sense to remember the order that succeeded across some fill_balloon() calls. Don't even expect it to compile ... >From 4305f989672ccca4be9293e6d4167e929f3e299b Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Tue, 31 Mar 2020 12:28:07 +0200 Subject: [PATCH RFC] tmp Signed-off-by: David Hildenbrand --- drivers/virtio/virtio_balloon.c | 38 ++++++++++++++++++-------- include/linux/balloon_compaction.h | 7 ++++- mm/balloon_compaction.c | 43 +++++++++++++++++++++++------- 3 files changed, 67 insertions(+), 21 deletions(-) diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_ball= oon.c index 8511d258dbb4..0660b1b988f0 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -187,7 +187,7 @@ int virtballoon_free_page_report(struct page_reportin= g_dev_info *pr_dev_info, } =20 static void set_page_pfns(struct virtio_balloon *vb, - __virtio32 pfns[], struct page *page) + __virtio32 pfns[], struct page *page, int order) { unsigned int i; =20 @@ -197,7 +197,7 @@ static void set_page_pfns(struct virtio_balloon *vb, * Set balloon pfns pointing at this page. * Note that the first pfn points at start of the page. */ - for (i =3D 0; i < VIRTIO_BALLOON_PAGES_PER_PAGE; i++) + for (i =3D 0; i < VIRTIO_BALLOON_PAGES_PER_PAGE * (1 << order); i++) pfns[i] =3D cpu_to_virtio32(vb->vdev, page_to_balloon_pfn(page) + i); } @@ -205,6 +205,7 @@ static void set_page_pfns(struct virtio_balloon *vb, static unsigned fill_balloon(struct virtio_balloon *vb, size_t num) { unsigned num_allocated_pages; + int order =3D MAX_ORDER - 1; unsigned num_pfns; struct page *page; LIST_HEAD(pages); @@ -212,9 +213,20 @@ static unsigned fill_balloon(struct virtio_balloon *= vb, size_t num) /* We can only do one array worth at a time. */ num =3D min(num, ARRAY_SIZE(vb->pfns)); =20 + /* + * Note: we will currently never allocate more than 1MB due to the + * pfn array size, so we will not allocate MAX_ORDER - 1 ... + */ + for (num_pfns =3D 0; num_pfns < num; - num_pfns +=3D VIRTIO_BALLOON_PAGES_PER_PAGE) { - struct page *page =3D balloon_page_alloc(); + num_pfns +=3D VIRTIO_BALLOON_PAGES_PER_PAGE * (1 << order)) { + const unsigned long remaining =3D num - num_pfns; + + order =3D MIN(order, + get_order(remaining << VIRTIO_BALLOON_PFN_SHIFT)); + if ((1 << order) * VIRTIO_BALLOON_PAGES_PER_PAGE > remaining) + order--; + page =3D balloon_pages_alloc(order); =20 if (!page) { dev_info_ratelimited(&vb->vdev->dev, @@ -225,6 +237,8 @@ static unsigned fill_balloon(struct virtio_balloon *v= b, size_t num) break; } =20 + /* Continue with the actual order that succeeded. */ + order =3D page_private(page); balloon_page_push(&pages, page); } =20 @@ -233,14 +247,16 @@ static unsigned fill_balloon(struct virtio_balloon = *vb, size_t num) vb->num_pfns =3D 0; =20 while ((page =3D balloon_page_pop(&pages))) { + order =3D page_order(page); + /* enqueuing will split the page and clear the order */ balloon_page_enqueue(&vb->vb_dev_info, page); =20 - set_page_pfns(vb, vb->pfns + vb->num_pfns, page); - vb->num_pages +=3D VIRTIO_BALLOON_PAGES_PER_PAGE; + set_page_pfns(vb, vb->pfns + vb->num_pfns, page, order); + vb->num_pages +=3D VIRTIO_BALLOON_PAGES_PER_PAGE * (1 << order); if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) - adjust_managed_page_count(page, -1); - vb->num_pfns +=3D VIRTIO_BALLOON_PAGES_PER_PAGE; + adjust_managed_page_count(page, -1 * (1 << order)); + vb->num_pfns +=3D VIRTIO_BALLOON_PAGES_PER_PAGE * (1 << order); } =20 num_allocated_pages =3D vb->num_pfns; @@ -284,7 +300,7 @@ static unsigned leak_balloon(struct virtio_balloon *v= b, size_t num) page =3D balloon_page_dequeue(vb_dev_info); if (!page) break; - set_page_pfns(vb, vb->pfns + vb->num_pfns, page); + set_page_pfns(vb, vb->pfns + vb->num_pfns, page, 0); list_add(&page->lru, &pages); vb->num_pages -=3D VIRTIO_BALLOON_PAGES_PER_PAGE; } @@ -786,7 +802,7 @@ static int virtballoon_migratepage(struct balloon_dev= _info *vb_dev_info, __count_vm_event(BALLOON_MIGRATE); spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags); vb->num_pfns =3D VIRTIO_BALLOON_PAGES_PER_PAGE; - set_page_pfns(vb, vb->pfns, newpage); + set_page_pfns(vb, vb->pfns, newpage, 0); tell_host(vb, vb->inflate_vq); =20 /* balloon's page migration 2nd step -- deflate "page" */ @@ -794,7 +810,7 @@ static int virtballoon_migratepage(struct balloon_dev= _info *vb_dev_info, balloon_page_delete(page); spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags); vb->num_pfns =3D VIRTIO_BALLOON_PAGES_PER_PAGE; - set_page_pfns(vb, vb->pfns, page); + set_page_pfns(vb, vb->pfns, page, 0); tell_host(vb, vb->deflate_vq); =20 mutex_unlock(&vb->balloon_lock); diff --git a/include/linux/balloon_compaction.h b/include/linux/balloon_c= ompaction.h index 338aa27e4773..ed93fe5704d1 100644 --- a/include/linux/balloon_compaction.h +++ b/include/linux/balloon_compaction.h @@ -60,7 +60,7 @@ struct balloon_dev_info { struct inode *inode; }; =20 -extern struct page *balloon_page_alloc(void); +extern struct page *balloon_pages_alloc(int order); extern void balloon_page_enqueue(struct balloon_dev_info *b_dev_info, struct page *page); extern struct page *balloon_page_dequeue(struct balloon_dev_info *b_dev_= info); @@ -78,6 +78,11 @@ static inline void balloon_devinfo_init(struct balloon= _dev_info *balloon) balloon->inode =3D NULL; } =20 +static inline struct page *balloon_page_alloc(void) +{ + return balloon_pages_alloc(0); +} + #ifdef CONFIG_BALLOON_COMPACTION extern const struct address_space_operations balloon_aops; extern bool balloon_page_isolate(struct page *page, diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c index 26de020aae7b..067810b32813 100644 --- a/mm/balloon_compaction.c +++ b/mm/balloon_compaction.c @@ -112,23 +112,35 @@ size_t balloon_page_list_dequeue(struct balloon_dev= _info *b_dev_info, EXPORT_SYMBOL_GPL(balloon_page_list_dequeue); =20 /* - * balloon_page_alloc - allocates a new page for insertion into the ball= oon - * page list. + * balloon_pages_alloc - allocates a new page (of at most the given orde= r) + * for insertion into the balloon page list. * * Driver must call this function to properly allocate a new balloon pag= e. * Driver must call balloon_page_enqueue before definitively removing th= e page * from the guest system. * + * Will fall back to smaller orders if allocation fails. The order of th= e + * allocated page is stored in page->private. + * * Return: struct page for the allocated page or NULL on allocation fail= ure. */ -struct page *balloon_page_alloc(void) +struct page *balloon_pages_alloc(int order) { - struct page *page =3D alloc_page(balloon_mapping_gfp_mask() | - __GFP_NOMEMALLOC | __GFP_NORETRY | - __GFP_NOWARN); - return page; + struct page *page; + + while (order >=3D 0) { + page =3D alloc_pages(balloon_mapping_gfp_mask() | + __GFP_NOMEMALLOC | __GFP_NORETRY | + __GFP_NOWARN, order); + if (page) { + set_page_private(page, order); + return page; + } + order--; + } + return NULL; } -EXPORT_SYMBOL_GPL(balloon_page_alloc); +EXPORT_SYMBOL_GPL(balloon_pages_alloc); =20 /* * balloon_page_enqueue - inserts a new page into the balloon page list. @@ -146,10 +158,23 @@ EXPORT_SYMBOL_GPL(balloon_page_alloc); void balloon_page_enqueue(struct balloon_dev_info *b_dev_info, struct page *page) { + const int order =3D page_private(page); unsigned long flags; + int i; + + /* + * We can only migrate single pages - and even if we could migrate + * bigger ones, we would want to split them on demand instead of + * trying to move around big chunks. + */ + if (order > 0) + split_page(page, order); + set_page_private(page, order); =20 spin_lock_irqsave(&b_dev_info->pages_lock, flags); - balloon_page_enqueue_one(b_dev_info, page); + for (i =3D 0; i < (1 << order); i++) + balloon_page_enqueue_one(b_dev_info, page + i); + spin_unlock_irqrestore(&b_dev_info->pages_lock, flags); } EXPORT_SYMBOL_GPL(balloon_page_enqueue); --=20 2.25.1 --=20 Thanks, David / dhildenb