From: Jason Wang <jasowang@redhat.com>
To: "Liu, Xiaodong" <xiaodong.liu@intel.com>,
Xie Yongji <xieyongji@bytedance.com>,
"mst@redhat.com" <mst@redhat.com>,
"stefanha@redhat.com" <stefanha@redhat.com>,
"sgarzare@redhat.com" <sgarzare@redhat.com>,
"parav@nvidia.com" <parav@nvidia.com>,
"hch@infradead.org" <hch@infradead.org>,
"christian.brauner@canonical.com"
<christian.brauner@canonical.com>,
"rdunlap@infradead.org" <rdunlap@infradead.org>,
"willy@infradead.org" <willy@infradead.org>,
"viro@zeniv.linux.org.uk" <viro@zeniv.linux.org.uk>,
"axboe@kernel.dk" <axboe@kernel.dk>,
"bcrl@kvack.org" <bcrl@kvack.org>,
"corbet@lwn.net" <corbet@lwn.net>,
"mika.penttila@nextfour.com" <mika.penttila@nextfour.com>,
"dan.carpenter@oracle.com" <dan.carpenter@oracle.com>,
"joro@8bytes.org" <joro@8bytes.org>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"virtualization@lists.linux-foundation.org"
<virtualization@lists.linux-foundation.org>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"songmuchun@bytedance.com" <songmuchun@bytedance.com>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH v8 00/10] Introduce VDUSE - vDPA Device in Userspace
Date: Tue, 29 Jun 2021 12:10:51 +0800 [thread overview]
Message-ID: <41cc419e-48b5-6755-0cb0-9033bd1310e4@redhat.com> (raw)
In-Reply-To: <BYAPR11MB2662FFF6140A4C634648BB2E8C039@BYAPR11MB2662.namprd11.prod.outlook.com>
在 2021/6/28 下午1:54, Liu, Xiaodong 写道:
>> Several issues:
>>
>> - VDUSE needs to limit the total size of the bounce buffers (64M if I was not
>> wrong). Does it work for SPDK?
> Yes, Jason. It is enough and works for SPDK.
> Since it's a kind of bounce buffer mainly for in-flight IO, so limited size like
> 64MB is enough.
Ok.
>
>> - VDUSE can use hugepages but I'm not sure we can mandate hugepages (or we
>> need introduce new flags for supporting this)
> Same with your worry, I'm afraid too that it is a hard for a kernel module
> to directly preallocate hugepage internal.
> What I tried is that:
> 1. A simple agent daemon (represents for one device) `preallocates` and maps
> dozens of 2MB hugepages (like 64MB) for one device.
> 2. The daemon passes its mapping addr&len and hugepage fd to kernel
> module through created IOCTL.
> 3. Kernel module remaps the hugepages inside kernel.
Such model should work, but the main "issue" is that it introduce
overheads in the case of vhost-vDPA.
Note that in the case of vhost-vDPA, we don't use bounce buffer, the
userspace pages were shared directly.
And since DMA is not done per page, it prevents us from using tricks
like vm_insert_page() in those cases.
> 4. Vhost user target gets and maps hugepage fd from kernel module
> in vhost-user msg through Unix Domain Socket cmsg.
> Then kernel module and target map on the same hugepage based
> bounce buffer for in-flight IO.
>
> If there is one option in VDUSE to map userspace preallocated memory, then
> VDUSE should be able to mandate it even it is hugepage based.
>
As above, this requires some kind of re-design since VDUSE depends on
the model of mmap(MAP_SHARED) instead of umem registering.
Thanks
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next prev parent reply other threads:[~2021-06-29 4:11 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-15 14:13 [PATCH v8 00/10] Introduce VDUSE - vDPA Device in Userspace Xie Yongji
2021-06-15 14:13 ` [PATCH v8 01/10] iova: Export alloc_iova_fast() and free_iova_fast(); Xie Yongji
2021-06-15 14:13 ` [PATCH v8 02/10] file: Export receive_fd() to modules Xie Yongji
2021-06-15 14:13 ` [PATCH v8 03/10] eventfd: Increase the recursion depth of eventfd_signal() Xie Yongji
2021-06-17 8:33 ` He Zhe
2021-06-18 3:29 ` Yongji Xie
2021-06-18 8:41 ` He Zhe
2021-06-18 8:44 ` [PATCH] eventfd: Enlarge recursion limit to allow vhost to work He Zhe
2021-07-03 8:31 ` Michael S. Tsirkin
2021-08-25 7:57 ` Yongji Xie
2021-06-15 14:13 ` [PATCH v8 04/10] vhost-iotlb: Add an opaque pointer for vhost IOTLB Xie Yongji
2021-06-15 14:13 ` [PATCH v8 05/10] vdpa: Add an opaque pointer for vdpa_config_ops.dma_map() Xie Yongji
2021-06-15 14:13 ` [PATCH v8 06/10] vdpa: factor out vhost_vdpa_pa_map() and vhost_vdpa_pa_unmap() Xie Yongji
2021-06-15 14:13 ` [PATCH v8 07/10] vdpa: Support transferring virtual addressing during DMA mapping Xie Yongji
2021-06-15 14:13 ` [PATCH v8 08/10] vduse: Implement an MMU-based IOMMU driver Xie Yongji
2021-06-15 14:13 ` [PATCH v8 09/10] vduse: Introduce VDUSE - vDPA Device in Userspace Xie Yongji
2021-06-21 9:13 ` Jason Wang
2021-06-21 10:41 ` Yongji Xie
2021-06-22 5:06 ` Jason Wang
2021-06-22 7:22 ` Yongji Xie
2021-06-22 7:49 ` Jason Wang
2021-06-22 8:14 ` Yongji Xie
2021-06-23 3:30 ` Jason Wang
2021-06-23 5:50 ` Yongji Xie
2021-06-24 3:34 ` Jason Wang
2021-06-24 4:46 ` Yongji Xie
2021-06-24 8:13 ` Jason Wang
2021-06-24 9:16 ` Yongji Xie
2021-06-25 3:08 ` Jason Wang
2021-06-25 4:19 ` Yongji Xie
2021-06-28 4:40 ` Jason Wang
2021-06-29 2:26 ` Yongji Xie
2021-06-29 3:29 ` Jason Wang
2021-06-29 3:56 ` Yongji Xie
2021-06-29 4:03 ` Jason Wang
2021-06-24 14:46 ` Stefan Hajnoczi
2021-06-29 2:59 ` Yongji Xie
2021-06-30 9:51 ` Stefan Hajnoczi
2021-07-01 6:50 ` Yongji Xie
2021-07-01 7:55 ` Jason Wang
2021-07-01 10:26 ` Yongji Xie
2021-07-02 3:25 ` Jason Wang
2021-07-07 8:52 ` Stefan Hajnoczi
2021-07-07 9:19 ` Yongji Xie
2021-06-15 14:13 ` [PATCH v8 10/10] Documentation: Add documentation for VDUSE Xie Yongji
2021-06-24 13:01 ` Stefan Hajnoczi
2021-06-29 5:43 ` Yongji Xie
2021-06-30 10:06 ` Stefan Hajnoczi
2021-07-01 10:00 ` Yongji Xie
2021-07-01 13:15 ` Stefan Hajnoczi
2021-07-04 9:49 ` Yongji Xie
2021-07-05 3:36 ` Jason Wang
2021-07-05 12:49 ` Stefan Hajnoczi
2021-07-06 2:34 ` Jason Wang
2021-07-06 10:14 ` Stefan Hajnoczi
[not found] ` <CACGkMEs2HHbUfarum8uQ6wuXoDwLQUSXTsa-huJFiqr__4cwRg@mail.gmail.com>
[not found] ` <YOSOsrQWySr0andk@stefanha-x1.localdomain>
[not found] ` <100e6788-7fdf-1505-d69c-bc28a8bc7a78@redhat.com>
[not found] ` <YOVr801d01YOPzLL@stefanha-x1.localdomain>
2021-07-07 9:24 ` Jason Wang
2021-07-07 15:54 ` Stefan Hajnoczi
2021-07-08 4:17 ` Jason Wang
2021-07-08 9:06 ` Stefan Hajnoczi
2021-07-08 12:35 ` Yongji Xie
2021-07-06 3:04 ` Yongji Xie
2021-07-06 10:22 ` Stefan Hajnoczi
2021-07-07 9:09 ` Yongji Xie
2021-07-08 9:07 ` Stefan Hajnoczi
2021-06-24 15:12 ` [PATCH v8 00/10] Introduce VDUSE - vDPA Device in Userspace Stefan Hajnoczi
2021-06-29 3:15 ` Yongji Xie
2021-06-28 10:33 ` Liu Xiaodong
2021-06-28 4:35 ` Jason Wang
2021-06-28 5:54 ` Liu, Xiaodong
2021-06-29 4:10 ` Jason Wang [this message]
2021-06-29 7:56 ` Liu, Xiaodong
2021-06-29 8:14 ` Yongji Xie
2021-06-28 10:32 ` Yongji Xie
2021-06-29 4:12 ` Jason Wang
2021-06-29 6:40 ` Yongji Xie
2021-06-29 7:33 ` Jason Wang
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