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[209.132.183.28]) by mx.google.com with ESMTPS id s15si11238186uao.57.2019.07.24.13.10.34 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 24 Jul 2019 13:10:35 -0700 (PDT) Received-SPF: pass (google.com: domain of nitesh@redhat.com designates 209.132.183.28 as permitted sender) client-ip=209.132.183.28; Authentication-Results: mx.google.com; spf=pass (google.com: domain of nitesh@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=nitesh@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 223DC8553D; Wed, 24 Jul 2019 20:10:34 +0000 (UTC) Received: from [10.18.17.163] (dhcp-17-163.bos.redhat.com [10.18.17.163]) by smtp.corp.redhat.com (Postfix) with ESMTPS id BA0FD5D9DE; Wed, 24 Jul 2019 20:10:22 +0000 (UTC) Subject: Re: [RFC][Patch v11 2/2] virtio-balloon: page_hinting: reporting to the host To: David Hildenbrand , "Michael S. Tsirkin" Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, pbonzini@redhat.com, lcapitulino@redhat.com, pagupta@redhat.com, wei.w.wang@intel.com, yang.zhang.wz@gmail.com, riel@surriel.com, dodgen@google.com, konrad.wilk@oracle.com, dhildenb@redhat.com, aarcange@redhat.com, alexander.duyck@gmail.com, john.starks@microsoft.com, dave.hansen@intel.com, mhocko@suse.com References: <20190710195158.19640-1-nitesh@redhat.com> <20190710195158.19640-3-nitesh@redhat.com> <20190724153951-mutt-send-email-mst@kernel.org> 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: Wed, 24 Jul 2019 16:10:22 -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: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Wed, 24 Jul 2019 20:10:34 +0000 (UTC) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 7/24/19 3:56 PM, David Hildenbrand wrote: > On 24.07.19 21:47, Michael S. Tsirkin wrote: >> On Wed, Jul 10, 2019 at 03:51:58PM -0400, 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/Kconfig | 1 + >>> drivers/virtio/virtio_balloon.c | 91 ++++++++++++++++++++++++++++- >>> include/uapi/linux/virtio_balloon.h | 11 ++++ >>> 3 files changed, 102 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig >>> index 023fc3bc01c6..dcc0cb4269a5 100644 >>> --- a/drivers/virtio/Kconfig >>> +++ b/drivers/virtio/Kconfig >>> @@ -47,6 +47,7 @@ config VIRTIO_BALLOON >>> tristate "Virtio balloon driver" >>> depends on VIRTIO >>> select MEMORY_BALLOON >>> + select PAGE_HINTING >>> ---help--- >>> This driver supports increasing and decreasing the amount >>> of memory within a KVM guest. >>> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c >>> index 44339fc87cc7..1fb0eb0b2c20 100644 >>> --- a/drivers/virtio/virtio_balloon.c >>> +++ b/drivers/virtio/virtio_balloon.c >>> @@ -18,6 +18,7 @@ >>> #include >>> #include >>> #include >>> +#include >>> >>> /* >>> * Balloon device works in 4K page units. So each page is pointed to by >>> @@ -35,6 +36,12 @@ >>> /* The size of a free page block in bytes */ >>> #define VIRTIO_BALLOON_FREE_PAGE_SIZE \ >>> (1 << (VIRTIO_BALLOON_FREE_PAGE_ORDER + PAGE_SHIFT)) >>> +/* Number of isolated pages to be reported to the host at a time. >>> + * TODO: >>> + * 1. Set it via host. >>> + * 2. Find an optimal value for this. >>> + */ >>> +#define PAGE_HINTING_MAX_PAGES 16 >>> >>> #ifdef CONFIG_BALLOON_COMPACTION >>> static struct vfsmount *balloon_mnt; >>> @@ -45,6 +52,7 @@ 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 >>> }; >>> >>> @@ -54,7 +62,8 @@ 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; >>> @@ -112,6 +121,9 @@ struct virtio_balloon { >>> >>> /* To register a shrinker to shrink memory upon memory pressure */ >>> struct shrinker shrinker; >>> + >>> + /* Array object pointing at the isolated pages ready for hinting */ >>> + struct isolated_memory isolated_pages[PAGE_HINTING_MAX_PAGES]; >>> }; >>> >>> static struct virtio_device_id id_table[] = { >>> @@ -119,6 +131,66 @@ static struct virtio_device_id id_table[] = { >>> { 0 }, >>> }; >>> >>> +static struct page_hinting_config page_hinting_conf; >>> +bool page_hinting_flag = true; >>> +struct virtio_balloon *hvb; >>> +module_param(page_hinting_flag, bool, 0444); >>> +MODULE_PARM_DESC(page_hinting_flag, "Enable page hinting"); >>> + >>> +static int page_hinting_report(void) >>> +{ >>> + struct virtqueue *vq = hvb->hinting_vq; >>> + struct scatterlist sg; >>> + int err = 0, unused; >>> + >>> + mutex_lock(&hvb->balloon_lock); >>> + sg_init_one(&sg, hvb->isolated_pages, sizeof(hvb->isolated_pages[0]) * >>> + PAGE_HINTING_MAX_PAGES); >>> + err = virtqueue_add_outbuf(vq, &sg, 1, hvb, GFP_KERNEL); >> In Alex's patch, I really like it that he's passing pages as sg >> entries. IMHO that's both cleaner and allows seamless >> support for arbitrary page sizes. >> > +1 > > I especially like passing full addresses and sizes instead of PFNs and > orders (compared to Alex's v1, where he would pass PFNs and orders). I agree it fixes the issues which could have been introduced due to different page sizes in the host and the guest. > -- Thanks Nitesh