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=-7.0 required=3.0 tests=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 5E83AC282CE for ; Tue, 4 Jun 2019 07:12:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 33D8624A6F for ; Tue, 4 Jun 2019 07:12:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726663AbfFDHMn (ORCPT ); Tue, 4 Jun 2019 03:12:43 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53618 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726568AbfFDHMn (ORCPT ); Tue, 4 Jun 2019 03:12:43 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C14D6C05FBCB; Tue, 4 Jun 2019 07:12:37 +0000 (UTC) Received: from [10.36.117.37] (ovpn-117-37.ams2.redhat.com [10.36.117.37]) by smtp.corp.redhat.com (Postfix) with ESMTP id 454185B684; Tue, 4 Jun 2019 07:12:22 +0000 (UTC) Subject: Re: [RFC][Patch v10 2/2] virtio-balloon: page_hinting: reporting to the host To: Alexander Duyck , Nitesh Narayan Lal Cc: kvm list , LKML , linux-mm , Paolo Bonzini , lcapitulino@redhat.com, pagupta@redhat.com, wei.w.wang@intel.com, Yang Zhang , Rik van Riel , "Michael S. Tsirkin" , dodgen@google.com, Konrad Rzeszutek Wilk , dhildenb@redhat.com, Andrea Arcangeli References: <20190603170306.49099-1-nitesh@redhat.com> <20190603170306.49099-3-nitesh@redhat.com> From: David Hildenbrand Openpgp: preference=signencrypt Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= xsFNBFXLn5EBEAC+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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwX4EEwECACgFAljj9eoCGwMFCQlmAYAGCwkI BwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEE3eEPcA/4Na5IIP/3T/FIQMxIfNzZshIq687qgG 8UbspuE/YSUDdv7r5szYTK6KPTlqN8NAcSfheywbuYD9A4ZeSBWD3/NAVUdrCaRP2IvFyELj xoMvfJccbq45BxzgEspg/bVahNbyuBpLBVjVWwRtFCUEXkyazksSv8pdTMAs9IucChvFmmq3 jJ2vlaz9lYt/lxN246fIVceckPMiUveimngvXZw21VOAhfQ+/sofXF8JCFv2mFcBDoa7eYob s0FLpmqFaeNRHAlzMWgSsP80qx5nWWEvRLdKWi533N2vC/EyunN3HcBwVrXH4hxRBMco3jvM m8VKLKao9wKj82qSivUnkPIwsAGNPdFoPbgghCQiBjBe6A75Z2xHFrzo7t1jg7nQfIyNC7ez MZBJ59sqA9EDMEJPlLNIeJmqslXPjmMFnE7Mby/+335WJYDulsRybN+W5rLT5aMvhC6x6POK z55fMNKrMASCzBJum2Fwjf/VnuGRYkhKCqqZ8gJ3OvmR50tInDV2jZ1DQgc3i550T5JDpToh dPBxZocIhzg+MBSRDXcJmHOx/7nQm3iQ6iLuwmXsRC6f5FbFefk9EjuTKcLMvBsEx+2DEx0E UnmJ4hVg7u1PQ+2Oy+Lh/opK/BDiqlQ8Pz2jiXv5xkECvr/3Sv59hlOCZMOaiLTTjtOIU7Tq 7ut6OL64oAq+zsFNBFXLn5EBEADn1959INH2cwYJv0tsxf5MUCghCj/CA/lc/LMthqQ773ga uB9mN+F1rE9cyyXb6jyOGn+GUjMbnq1o121Vm0+neKHUCBtHyseBfDXHA6m4B3mUTWo13nid 0e4AM71r0DS8+KYh6zvweLX/LL5kQS9GQeT+QNroXcC1NzWbitts6TZ+IrPOwT1hfB4WNC+X 2n4AzDqp3+ILiVST2DT4VBc11Gz6jijpC/KI5Al8ZDhRwG47LUiuQmt3yqrmN63V9wzaPhC+ xbwIsNZlLUvuRnmBPkTJwwrFRZvwu5GPHNndBjVpAfaSTOfppyKBTccu2AXJXWAE1Xjh6GOC 8mlFjZwLxWFqdPHR1n2aPVgoiTLk34LR/bXO+e0GpzFXT7enwyvFFFyAS0Nk1q/7EChPcbRb hJqEBpRNZemxmg55zC3GLvgLKd5A09MOM2BrMea+l0FUR+PuTenh2YmnmLRTro6eZ/qYwWkC u8FFIw4pT0OUDMyLgi+GI1aMpVogTZJ70FgV0pUAlpmrzk/bLbRkF3TwgucpyPtcpmQtTkWS gDS50QG9DR/1As3LLLcNkwJBZzBG6PWbvcOyrwMQUF1nl4SSPV0LLH63+BrrHasfJzxKXzqg rW28CTAE2x8qi7e/6M/+XXhrsMYG+uaViM7n2je3qKe7ofum3s4vq7oFCPsOgwARAQABwsFl BBgBAgAPBQJVy5+RAhsMBQkJZgGAAAoJEE3eEPcA/4NagOsP/jPoIBb/iXVbM+fmSHOjEshl KMwEl/m5iLj3iHnHPVLBUWrXPdS7iQijJA/VLxjnFknhaS60hkUNWexDMxVVP/6lbOrs4bDZ NEWDMktAeqJaFtxackPszlcpRVkAs6Msn9tu8hlvB517pyUgvuD7ZS9gGOMmYwFQDyytpepo YApVV00P0u3AaE0Cj/o71STqGJKZxcVhPaZ+LR+UCBZOyKfEyq+ZN311VpOJZ1IvTExf+S/5 lqnciDtbO3I4Wq0ArLX1gs1q1XlXLaVaA3yVqeC8E7kOchDNinD3hJS4OX0e1gdsx/e6COvy qNg5aL5n0Kl4fcVqM0LdIhsubVs4eiNCa5XMSYpXmVi3HAuFyg9dN+x8thSwI836FoMASwOl C7tHsTjnSGufB+D7F7ZBT61BffNBBIm1KdMxcxqLUVXpBQHHlGkbwI+3Ye+nE6HmZH7IwLwV W+Ajl7oYF+jeKaH4DZFtgLYGLtZ1LDwKPjX7VAsa4Yx7S5+EBAaZGxK510MjIx6SGrZWBrrV TEvdV00F2MnQoeXKzD7O4WFbL55hhyGgfWTHwZ457iN9SgYi1JLPqWkZB0JRXIEtjd4JEQcx +8Umfre0Xt4713VxMygW0PnQt5aSQdMD58jHFxTk092mU+yIHj5LeYgvwSgZN4airXk5yRXl SE+xAvmumFBY Organization: Red Hat GmbH Message-ID: <604c496d-4df0-dca9-76dd-048917a5d132@redhat.com> Date: Tue, 4 Jun 2019 09:12:21 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Tue, 04 Jun 2019 07:12:41 +0000 (UTC) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 04.06.19 00:38, Alexander Duyck wrote: > On Mon, Jun 3, 2019 at 10:04 AM Nitesh Narayan Lal wrote: >> >> Enables the kernel to negotiate VIRTIO_BALLOON_F_HINTING feature with the >> host. If it is available and page_hinting_flag is set to true, page_hinting >> is enabled and its callbacks are configured along with the max_pages count >> which indicates the maximum number of pages that can be isolated and hinted >> at a time. Currently, only free pages of order >= (MAX_ORDER - 2) are >> reported. To prevent any false OOM max_pages count is set to 16. >> >> By default page_hinting feature is enabled and gets loaded as soon >> as the virtio-balloon driver is loaded. However, it could be disabled >> by writing the page_hinting_flag which is a virtio-balloon parameter. >> >> Signed-off-by: Nitesh Narayan Lal >> --- >> drivers/virtio/virtio_balloon.c | 112 +++++++++++++++++++++++++++- >> include/uapi/linux/virtio_balloon.h | 14 ++++ >> 2 files changed, 125 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c >> index f19061b585a4..40f09ea31643 100644 >> --- a/drivers/virtio/virtio_balloon.c >> +++ b/drivers/virtio/virtio_balloon.c >> @@ -31,6 +31,7 @@ >> #include >> #include >> #include >> +#include >> >> /* >> * Balloon device works in 4K page units. So each page is pointed to by >> @@ -48,6 +49,7 @@ >> /* The size of a free page block in bytes */ >> #define VIRTIO_BALLOON_FREE_PAGE_SIZE \ >> (1 << (VIRTIO_BALLOON_FREE_PAGE_ORDER + PAGE_SHIFT)) >> +#define VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES 16 >> >> #ifdef CONFIG_BALLOON_COMPACTION >> static struct vfsmount *balloon_mnt; >> @@ -58,6 +60,7 @@ enum virtio_balloon_vq { >> VIRTIO_BALLOON_VQ_DEFLATE, >> VIRTIO_BALLOON_VQ_STATS, >> VIRTIO_BALLOON_VQ_FREE_PAGE, >> + VIRTIO_BALLOON_VQ_HINTING, >> VIRTIO_BALLOON_VQ_MAX >> }; >> >> @@ -67,7 +70,8 @@ enum virtio_balloon_config_read { >> >> struct virtio_balloon { >> struct virtio_device *vdev; >> - struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq; >> + struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq, >> + *hinting_vq; >> >> /* Balloon's own wq for cpu-intensive work items */ >> struct workqueue_struct *balloon_wq; >> @@ -125,6 +129,9 @@ struct virtio_balloon { >> >> /* To register a shrinker to shrink memory upon memory pressure */ >> struct shrinker shrinker; >> + >> + /* object pointing at the array of isolated pages ready for hinting */ >> + struct hinting_data *hinting_arr; > > Just make this an array of size VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES. > It will save a bunch of complexity later. +1 [...] > >> +struct virtio_balloon *hvb; >> +bool page_hinting_flag = true; >> +module_param(page_hinting_flag, bool, 0444); >> +MODULE_PARM_DESC(page_hinting_flag, "Enable page hinting"); >> + >> +static bool virtqueue_kick_sync(struct virtqueue *vq) >> +{ >> + u32 len; >> + >> + if (likely(virtqueue_kick(vq))) { >> + while (!virtqueue_get_buf(vq, &len) && >> + !virtqueue_is_broken(vq)) >> + cpu_relax(); >> + return true; > > Is this a synchronous setup? It seems kind of wasteful to have a > thread busy waiting here like this. It might make more sense to just > make this work like the other balloon queues and have a wait event > with a wake up in the interrupt handler for the queue. +1 [...] > >> + gpaddr = virt_to_phys(hvb->hinting_arr); >> + hint_req->phys_addr = cpu_to_virtio64(hvb->vdev, gpaddr); >> + hint_req->size = cpu_to_virtio32(hvb->vdev, entries); >> + sg_init_one(&sg, hint_req, sizeof(*hint_req)); >> + err = virtqueue_add_outbuf(vq, &sg, 1, hint_req, GFP_KERNEL); >> + if (!err) >> + virtqueue_kick_sync(hvb->hinting_vq); >> + >> + kfree(hint_req); >> +} >> + >> +int page_hinting_prepare(void) >> +{ >> + hvb->hinting_arr = kmalloc_array(VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES, >> + sizeof(*hvb->hinting_arr), GFP_KERNEL); >> + if (!hvb->hinting_arr) >> + return -ENOMEM; >> + return 0; >> +} >> + > > Why make the hinting_arr a dynamic allocation? You should probably > just make it a static array within the virtio_balloon structure. Then > you don't have the risk of an allocation failing and messing up the > hints. +1 > >> +void hint_pages(struct list_head *pages) >> +{ >> + struct page *page, *next; >> + unsigned long pfn; >> + int idx = 0, order; >> + >> + list_for_each_entry_safe(page, next, pages, lru) { >> + pfn = page_to_pfn(page); >> + order = page_private(page); >> + hvb->hinting_arr[idx].phys_addr = pfn << PAGE_SHIFT; >> + hvb->hinting_arr[idx].size = (1 << order) * PAGE_SIZE; >> + idx++; >> + } >> + page_hinting_report(idx); >> +} >> + > > Getting back to my suggestion from earlier today. It might make sense > to not bother with the PAGE_SHIFT or PAGE_SIZE multiplication if you > just record everything in VIRTIO_BALLOON_PAGES intead of using the > actual address and size. I think I prefer "addr + size". > > Same comment here. Make this array a part of virtio_balloon and you > don't have to free it. > >> +static const struct page_hinting_cb hcb = { >> + .prepare = page_hinting_prepare, >> + .hint_pages = hint_pages, >> + .cleanup = page_hinting_cleanup, >> + .max_pages = VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES, >> +}; > > With the above changes prepare and cleanup can be dropped. +1 > >> +#endif >> + >> static u32 page_to_balloon_pfn(struct page *page) >> { >> unsigned long pfn = page_to_pfn(page); >> @@ -488,6 +574,7 @@ static int init_vqs(struct virtio_balloon *vb) >> names[VIRTIO_BALLOON_VQ_DEFLATE] = "deflate"; >> names[VIRTIO_BALLOON_VQ_STATS] = NULL; >> names[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL; >> + names[VIRTIO_BALLOON_VQ_HINTING] = NULL; >> >> if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { >> names[VIRTIO_BALLOON_VQ_STATS] = "stats"; >> @@ -499,11 +586,18 @@ static int init_vqs(struct virtio_balloon *vb) >> callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL; >> } >> >> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING)) { >> + names[VIRTIO_BALLOON_VQ_HINTING] = "hinting_vq"; >> + callbacks[VIRTIO_BALLOON_VQ_HINTING] = NULL; >> + } >> err = vb->vdev->config->find_vqs(vb->vdev, VIRTIO_BALLOON_VQ_MAX, >> vqs, callbacks, names, NULL, NULL); >> if (err) >> return err; >> >> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING)) >> + vb->hinting_vq = vqs[VIRTIO_BALLOON_VQ_HINTING]; >> + >> vb->inflate_vq = vqs[VIRTIO_BALLOON_VQ_INFLATE]; >> vb->deflate_vq = vqs[VIRTIO_BALLOON_VQ_DEFLATE]; >> if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { >> @@ -942,6 +1036,14 @@ static int virtballoon_probe(struct virtio_device *vdev) >> if (err) >> goto out_del_balloon_wq; >> } >> + >> +#ifdef CONFIG_PAGE_HINTING >> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING) && >> + page_hinting_flag) { >> + hvb = vb; >> + page_hinting_enable(&hcb); >> + } >> +#endif >> virtio_device_ready(vdev); >> >> if (towards_target(vb)) >> @@ -989,6 +1091,12 @@ static void virtballoon_remove(struct virtio_device *vdev) >> destroy_workqueue(vb->balloon_wq); >> } >> >> +#ifdef CONFIG_PAGE_HINTING >> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING)) { Nitesh, you should only disable if you actually enabled it (page_hinting_flag). -- Thanks, David / dhildenb