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 06B80C282CE for ; Tue, 4 Jun 2019 11:51:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CAC132133D for ; Tue, 4 Jun 2019 11:51:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727380AbfFDLvW (ORCPT ); Tue, 4 Jun 2019 07:51:22 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39828 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727250AbfFDLvV (ORCPT ); Tue, 4 Jun 2019 07:51:21 -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 mx1.redhat.com (Postfix) with ESMTPS id A9496A3B72; Tue, 4 Jun 2019 11:51:20 +0000 (UTC) Received: from [10.40.205.182] (unknown [10.40.205.182]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 45D6867260; Tue, 4 Jun 2019 11:50:53 +0000 (UTC) Subject: Re: [RFC][Patch v10 2/2] virtio-balloon: page_hinting: reporting to the host To: David Hildenbrand , Alexander Duyck 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> <604c496d-4df0-dca9-76dd-048917a5d132@redhat.com> From: Nitesh Narayan Lal Openpgp: preference=signencrypt Autocrypt: addr=nitesh@redhat.com; prefer-encrypt=mutual; keydata= mQINBFl4pQoBEADT/nXR2JOfsCjDgYmE2qonSGjkM1g8S6p9UWD+bf7YEAYYYzZsLtbilFTe z4nL4AV6VJmC7dBIlTi3Mj2eymD/2dkKP6UXlliWkq67feVg1KG+4UIp89lFW7v5Y8Muw3Fm uQbFvxyhN8n3tmhRe+ScWsndSBDxYOZgkbCSIfNPdZrHcnOLfA7xMJZeRCjqUpwhIjxQdFA7 n0s0KZ2cHIsemtBM8b2WXSQG9CjqAJHVkDhrBWKThDRF7k80oiJdEQlTEiVhaEDURXq+2XmG jpCnvRQDb28EJSsQlNEAzwzHMeplddfB0vCg9fRk/kOBMDBtGsTvNT9OYUZD+7jaf0gvBvBB lbKmmMMX7uJB+ejY7bnw6ePNrVPErWyfHzR5WYrIFUtgoR3LigKnw5apzc7UIV9G8uiIcZEn C+QJCK43jgnkPcSmwVPztcrkbC84g1K5v2Dxh9amXKLBA1/i+CAY8JWMTepsFohIFMXNLj+B RJoOcR4HGYXZ6CAJa3Glu3mCmYqHTOKwezJTAvmsCLd3W7WxOGF8BbBjVaPjcZfavOvkin0u DaFvhAmrzN6lL0msY17JCZo046z8oAqkyvEflFbC0S1R/POzehKrzQ1RFRD3/YzzlhmIowkM BpTqNBeHEzQAlIhQuyu1ugmQtfsYYq6FPmWMRfFPes/4JUU/PQARAQABtCVOaXRlc2ggTmFy YXlhbiBMYWwgPG5pbGFsQHJlZGhhdC5jb20+iQI9BBMBCAAnBQJZeKUKAhsjBQkJZgGABQsJ CAcCBhUICQoLAgQWAgMBAh4BAheAAAoJEKOGQNwGMqM56lEP/A2KMs/pu0URcVk/kqVwcBhU SnvB8DP3lDWDnmVrAkFEOnPX7GTbactQ41wF/xwjwmEmTzLrMRZpkqz2y9mV0hWHjqoXbOCS 6RwK3ri5e2ThIPoGxFLt6TrMHgCRwm8YuOSJ97o+uohCTN8pmQ86KMUrDNwMqRkeTRW9wWIQ EdDqW44VwelnyPwcmWHBNNb1Kd8j3xKlHtnS45vc6WuoKxYRBTQOwI/5uFpDZtZ1a5kq9Ak/ MOPDDZpd84rqd+IvgMw5z4a5QlkvOTpScD21G3gjmtTEtyfahltyDK/5i8IaQC3YiXJCrqxE r7/4JMZeOYiKpE9iZMtS90t4wBgbVTqAGH1nE/ifZVAUcCtycD0f3egX9CHe45Ad4fsF3edQ ESa5tZAogiA4Hc/yQpnnf43a3aQ67XPOJXxS0Qptzu4vfF9h7kTKYWSrVesOU3QKYbjEAf95 NewF9FhAlYqYrwIwnuAZ8TdXVDYt7Z3z506//sf6zoRwYIDA8RDqFGRuPMXUsoUnf/KKPrtR ceLcSUP/JCNiYbf1/QtW8S6Ca/4qJFXQHp0knqJPGmwuFHsarSdpvZQ9qpxD3FnuPyo64S2N Dfq8TAeifNp2pAmPY2PAHQ3nOmKgMG8Gn5QiORvMUGzSz8Lo31LW58NdBKbh6bci5+t/HE0H pnyVf5xhNC/FuQINBFl4pQoBEACr+MgxWHUP76oNNYjRiNDhaIVtnPRqxiZ9v4H5FPxJy9UD Bqr54rifr1E+K+yYNPt/Po43vVL2cAyfyI/LVLlhiY4yH6T1n+Di/hSkkviCaf13gczuvgz4 KVYLwojU8+naJUsiCJw01MjO3pg9GQ+47HgsnRjCdNmmHiUQqksMIfd8k3reO9SUNlEmDDNB XuSzkHjE5y/R/6p8uXaVpiKPfHoULjNRWaFc3d2JGmxJpBdpYnajoz61m7XJlgwl/B5Ql/6B dHGaX3VHxOZsfRfugwYF9CkrPbyO5PK7yJ5vaiWre7aQ9bmCtXAomvF1q3/qRwZp77k6i9R3 tWfXjZDOQokw0u6d6DYJ0Vkfcwheg2i/Mf/epQl7Pf846G3PgSnyVK6cRwerBl5a68w7xqVU 4KgAh0DePjtDcbcXsKRT9D63cfyfrNE+ea4i0SVik6+N4nAj1HbzWHTk2KIxTsJXypibOKFX 2VykltxutR1sUfZBYMkfU4PogE7NjVEU7KtuCOSAkYzIWrZNEQrxYkxHLJsWruhSYNRsqVBy KvY6JAsq/i5yhVd5JKKU8wIOgSwC9P6mXYRgwPyfg15GZpnw+Fpey4bCDkT5fMOaCcS+vSU1 UaFmC4Ogzpe2BW2DOaPU5Ik99zUFNn6cRmOOXArrryjFlLT5oSOe4IposgWzdwARAQABiQIl BBgBCAAPBQJZeKUKAhsMBQkJZgGAAAoJEKOGQNwGMqM5ELoP/jj9d9gF1Al4+9bngUlYohYu 0sxyZo9IZ7Yb7cHuJzOMqfgoP4tydP4QCuyd9Q2OHHL5AL4VFNb8SvqAxxYSPuDJTI3JZwI7 d8JTPKwpulMSUaJE8ZH9n8A/+sdC3CAD4QafVBcCcbFe1jifHmQRdDrvHV9Es14QVAOTZhnJ vweENyHEIxkpLsyUUDuVypIo6y/Cws+EBCWt27BJi9GH/EOTB0wb+2ghCs/i3h8a+bi+bS7L FCCm/AxIqxRurh2UySn0P/2+2eZvneJ1/uTgfxnjeSlwQJ1BWzMAdAHQO1/lnbyZgEZEtUZJ x9d9ASekTtJjBMKJXAw7GbB2dAA/QmbA+Q+Xuamzm/1imigz6L6sOt2n/X/SSc33w8RJUyor SvAIoG/zU2Y76pKTgbpQqMDmkmNYFMLcAukpvC4ki3Sf086TdMgkjqtnpTkEElMSFJC8npXv 3QnGGOIfFug/qs8z03DLPBz9VYS26jiiN7QIJVpeeEdN/LKnaz5LO+h5kNAyj44qdF2T2AiF HxnZnxO5JNP5uISQH3FjxxGxJkdJ8jKzZV7aT37sC+Rp0o3KNc+GXTR+GSVq87Xfuhx0LRST NK9ZhT0+qkiN7npFLtNtbzwqaqceq3XhafmCiw8xrtzCnlB/C4SiBr/93Ip4kihXJ0EuHSLn VujM7c/b4pps Organization: Red Hat Inc, Message-ID: Date: Tue, 4 Jun 2019 07:50:49 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <604c496d-4df0-dca9-76dd-048917a5d132@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="6NjG9l3ZfUIWqwgW8Rw3j6IdLhDSgrraq" X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Tue, 04 Jun 2019 11:51:20 +0000 (UTC) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --6NjG9l3ZfUIWqwgW8Rw3j6IdLhDSgrraq Content-Type: multipart/mixed; boundary="wbKqH0DBWRbbu6CF4s9EnEBmdNfs4bh6x"; protected-headers="v1" From: Nitesh Narayan Lal To: David Hildenbrand , Alexander Duyck 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 Message-ID: Subject: Re: [RFC][Patch v10 2/2] virtio-balloon: page_hinting: reporting to the host References: <20190603170306.49099-1-nitesh@redhat.com> <20190603170306.49099-3-nitesh@redhat.com> <604c496d-4df0-dca9-76dd-048917a5d132@redhat.com> In-Reply-To: <604c496d-4df0-dca9-76dd-048917a5d132@redhat.com> --wbKqH0DBWRbbu6CF4s9EnEBmdNfs4bh6x Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Language: en-US On 6/4/19 3:12 AM, David Hildenbrand wrote: > 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_h= inting >>> 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 >=3D (MAX_ORDER - 2) a= re >>> 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 t= o 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_p= age_vq; >>> + struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_p= age_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 pressu= re */ >>> struct shrinker shrinker; >>> + >>> + /* object pointing at the array of isolated pages ready for h= inting */ >>> + 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 =3D 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 =3D virt_to_phys(hvb->hinting_arr); >>> + hint_req->phys_addr =3D cpu_to_virtio64(hvb->vdev, gpaddr); >>> + hint_req->size =3D cpu_to_virtio32(hvb->vdev, entries); >>> + sg_init_one(&sg, hint_req, sizeof(*hint_req)); >>> + err =3D 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 =3D kmalloc_array(VIRTIO_BALLOON_PAGE_HINTIN= G_MAX_PAGES, >>> + sizeof(*hvb->hinting_arr), G= FP_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 =3D 0, order; >>> + >>> + list_for_each_entry_safe(page, next, pages, lru) { >>> + pfn =3D page_to_pfn(page); >>> + order =3D page_private(page); >>> + hvb->hinting_arr[idx].phys_addr =3D pfn << PAGE_SHIFT= ; >>> + hvb->hinting_arr[idx].size =3D (1 << order) * PAGE_SI= ZE; >>> + 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 =3D { >>> + .prepare =3D page_hinting_prepare, >>> + .hint_pages =3D hint_pages, >>> + .cleanup =3D page_hinting_cleanup, >>> + .max_pages =3D 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 =3D page_to_pfn(page); >>> @@ -488,6 +574,7 @@ static int init_vqs(struct virtio_balloon *vb) >>> names[VIRTIO_BALLOON_VQ_DEFLATE] =3D "deflate"; >>> names[VIRTIO_BALLOON_VQ_STATS] =3D NULL; >>> names[VIRTIO_BALLOON_VQ_FREE_PAGE] =3D NULL; >>> + names[VIRTIO_BALLOON_VQ_HINTING] =3D NULL; >>> >>> if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) = { >>> names[VIRTIO_BALLOON_VQ_STATS] =3D "stats"; >>> @@ -499,11 +586,18 @@ static int init_vqs(struct virtio_balloon *vb) >>> callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] =3D NULL; >>> } >>> >>> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING)) {= >>> + names[VIRTIO_BALLOON_VQ_HINTING] =3D "hinting_vq"; >>> + callbacks[VIRTIO_BALLOON_VQ_HINTING] =3D NULL; >>> + } >>> err =3D vb->vdev->config->find_vqs(vb->vdev, VIRTIO_BALLOON_V= Q_MAX, >>> vqs, callbacks, names, NULL,= NULL); >>> if (err) >>> return err; >>> >>> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING)) >>> + vb->hinting_vq =3D vqs[VIRTIO_BALLOON_VQ_HINTING]; >>> + >>> vb->inflate_vq =3D vqs[VIRTIO_BALLOON_VQ_INFLATE]; >>> vb->deflate_vq =3D 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_devi= ce *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 =3D vb; >>> + page_hinting_enable(&hcb); >>> + } >>> +#endif >>> virtio_device_ready(vdev); >>> >>> if (towards_target(vb)) >>> @@ -989,6 +1091,12 @@ static void virtballoon_remove(struct virtio_de= vice *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). +1, thanks. > > --=20 Regards Nitesh --wbKqH0DBWRbbu6CF4s9EnEBmdNfs4bh6x-- --6NjG9l3ZfUIWqwgW8Rw3j6IdLhDSgrraq Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEkXcoRVGaqvbHPuAGo4ZA3AYyozkFAlz2WxkACgkQo4ZA3AYy ozm1FQ//XVKSJNgjmz/qdXNXpETt9ez/6slhNIBrFzlSaoU3WUS+dR3ZFQOSBLoA G7RqLPYmhgh56fmgTd5hHEOYAtsYvAM76QfLZL2lRGN+4ePaqxO4UN81Ooz6qszr yJf39XennhsYuYX33BGlg9bBn4wVSmt81wzTN//f0eto7guAdBtuhNdE6oNA8jOm YNN28AmKKTWS/gwsurfxNc/gSv8l+PrrFqkXUH3KLGgYH9JJpHoh1xJvCEhbEbj/ fkDoLeeCaRGUBCZi8ykl+e+jpxucnP17gxtv+AYu+KuWH7zrz46vUzaTdVxcujHT OKhBVI/KdHpVmcoIQf8z3lWgSMQvMVvXTvtxi+l44oeke6ojIR+ZR2VYYPodW1VG e7UaDPd+BZtErJTVgOYmjd+tOShCP32j51H14kMvXgnDj/rNBPpUCzpHClSXF3o1 pKrHdDLNDSY//sk/nL+PVCLKQQDdwCZvFgkni3/uunl4QtlKdNIqTkhEhfLL9Fhv su6yHpUEajB/lLllatOU6i1Q3vr/RQFIQUiyVFpRJ/B1YmwQVDkQAEKbBC30g9+T ZeLp0cZEB4obElNWc9UGeHLPq1JF4I6LgXjpopGfsyj5tC6u+wZ5TlruM6UM079r tPNzZ96Oy5n9zLbVnsGLUmoQlZZMqP/yz8TkKC6UPmvv1kbwEG4= =vf8e -----END PGP SIGNATURE----- --6NjG9l3ZfUIWqwgW8Rw3j6IdLhDSgrraq--