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Violators will be prosecuted for from ; Thu, 27 Dec 2018 11:59:15 -0000 Subject: Re: [PATCH v37 0/3] Virtio-balloon: support free page reporting From: Christian Borntraeger References: <1535333539-32420-1-git-send-email-wei.w.wang@intel.com> <0661b05a-d9d0-d374-44e8-2583463e94c2@de.ibm.com> Date: Thu, 27 Dec 2018 12:59:04 +0100 In-Reply-To: <0661b05a-d9d0-d374-44e8-2583463e94c2@de.ibm.com> Content-Language: en-US Message-Id: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: Quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Wei Wang , virtio-dev@lists.oasis-open.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, linux-mm@kvack.org, mst@redhat.com, mhocko@kernel.org, akpm@linux-foundation.org, dgilbert@redhat.com Cc: torvalds@linux-foundation.org, pbonzini@redhat.com, liliang.opensource@gmail.com, yang.zhang.wz@gmail.com, quan.xu0@gmail.com, nilal@redhat.com, riel@redhat.com, peterx@redhat.com, quintela@redhat.com, Halil Pasic , Cornelia Huck On 27.12.2018 12:31, Christian Borntraeger wrote: > This patch triggers random crashes in the guest kernel on s390 early duri= ng boot. > No migration and no setting of the balloon is involved. >=20 Adding Conny and Halil, As the QEMU provides no PAGE_HINT feature yet, this quick hack makes the guest boot fine again: diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloo= n.c index 728ecd1eea305..aa2e1864c5736 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -492,7 +492,7 @@ static int init_vqs(struct virtio_balloon *vb) callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] =3D NULL; } =20 - err =3D vb->vdev->config->find_vqs(vb->vdev, VIRTIO_BALLOON_VQ_MAX, + err =3D vb->vdev->config->find_vqs(vb->vdev, 3, //VIRTIO_BALLOON_VQ= _MAX, vqs, callbacks, names, NULL, NULL); if (err) return err; To me it looks like that virtio_ccw_find_vqs will abort if any of the virtq= ueues=20 that it is been asked for does not exist (including the earlier ones). Christian >=20 > On 27.08.2018 03:32, Wei Wang wrote: >> The new feature, VIRTIO_BALLOON_F_FREE_PAGE_HINT, implemented by this >> series enables the virtio-balloon driver to report hints of guest free >> pages to host. It can be used to accelerate virtual machine (VM) live >> migration. Here is an introduction of this usage: >> >> Live migration needs to transfer the VM's memory from the source machine >> to the destination round by round. For the 1st round, all the VM's memory >> is transferred. From the 2nd round, only the pieces of memory that were >> written by the guest (after the 1st round) are transferred. One method >> that is popularly used by the hypervisor to track which part of memory is >> written is to have the hypervisor write-protect all the guest memory. >> >> This feature enables the optimization by skipping the transfer of guest >> free pages during VM live migration. It is not concerned that the memory >> pages are used after they are given to the hypervisor as a hint of the >> free pages, because they will be tracked by the hypervisor and transferr= ed >> in the subsequent round if they are used and written. >> >> * Tests >> 1 Test Environment >> Host: Intel(R) Xeon(R) CPU E5-2699 v4 @ 2.20GHz >> Migration setup: migrate_set_speed 100G, migrate_set_downtime 400ms >> >> 2 Test Results (results are averaged over several repeated runs) >> 2.1 Guest setup: 8G RAM, 4 vCPU >> 2.1.1 Idle guest live migration time >> Optimization v.s. Legacy =3D 620ms vs 2970ms >> --> ~79% reduction >> 2.1.2 Guest live migration with Linux compilation workload >> (i.e. make bzImage -j4) running >> 1) Live Migration Time: >> Optimization v.s. Legacy =3D 2273ms v.s. 4502ms >> --> ~50% reduction >> 2) Linux Compilation Time: >> Optimization v.s. Legacy =3D 8min42s v.s. 8min43s >> --> no obvious difference >> >> 2.2 Guest setup: 128G RAM, 4 vCPU >> 2.2.1 Idle guest live migration time >> Optimization v.s. Legacy =3D 5294ms vs 41651ms >> --> ~87% reduction >> 2.2.2 Guest live migration with Linux compilation workload >> 1) Live Migration Time: >> Optimization v.s. Legacy =3D 8816ms v.s. 54201ms >> --> 84% reduction >> 2) Linux Compilation Time: >> Optimization v.s. Legacy =3D 8min30s v.s. 8min36s >> --> no obvious difference >> >> ChangeLog: >> v36->v37: >> - free the reported pages to mm when receives a DONE cmd from host. >> Please see patch 1's commit log for reasons. Please see patch 1's >> commit for detailed explanations. >> >> For ChangeLogs from v22 to v36, please reference >> https://lkml.org/lkml/2018/7/20/199 >> >> For ChangeLogs before v21, please reference >> https://lwn.net/Articles/743660/ >> >> Wei Wang (3): >> virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT >> mm/page_poison: expose page_poisoning_enabled to kernel modules >> virtio-balloon: VIRTIO_BALLOON_F_PAGE_POISON >> >> drivers/virtio/virtio_balloon.c | 374 +++++++++++++++++++++++++++++= +++---- >> include/uapi/linux/virtio_balloon.h | 8 + >> mm/page_poison.c | 6 + >> 3 files changed, 355 insertions(+), 33 deletions(-) >>