Re: [Qemu-devel] [PATCH -V6 00/21] virtio-9p: paravirtual file system passthrough

[Anthony Liguori <aliguori@linux.vnet.ibm.com>]

On 04/29/2010 07:14 AM, Aneesh Kumar K.V wrote:
> Hi,
>
> This patch series adds VirtFS to QEMU. VirtFS is code named for a 9P filesystem
> server in QEMU enabling paravirtual filesystem pass-trhough between KVM host and guest.
>    

Applied all.  Thanks.

Regards,

Anthony Liguori

> VirtFS is intended to offer an alternative to using NFS/CIFS to share host filesystems on
> guest and provides better performance. Initial tests showed significantly better performance
> than NFS and CIFS. Performance numbers are provided towards end of the mail.
>
> With the current implementation, all I/O is implemented in the VCPU thread.
> We've modified the protocol handlers so that we can support dispatch I/O in a thread pool.
> The actual thread pool implementation will be posted later.
>
> This patch set should work with any recent Linux kernel as virtio-9p has been
> supported for a few kernel releases now. Export dir is specified using the below
> Qemu option.
>
> -fsdev fstype,id=ID,path=path/to/share \
>             -device virtio-9p-pci,fsdev=ID,mount_tag=tag \
> or
>
> -virtfs fstype,path=path/to/share,mount_tag=tag
>
> Only supported fstype currently is "local". mount_tag is used to identify
> the mount point in the kernel. This will be available in Linux
> kernel via /sys/devices/virtio-pci/virtio1/mount_tag file.
>
> Changes from V5:
> 1) Rebased to qemu master 9ed7b059ef776a3921cfd085e891f45076922542
> 2) Use endian conversion when passing tag len from qemu to guest.
> 3) Use QLIST instead of open coding a list
> 4) Fix build error with a srcdir != objdir
> 5) Remove --enable/disable-linux-virtfs. VirtFS is now default enabled on linux
>
> Changes from V4:
> 1) Rebased to qemu master bf3de7f16f2ab9e2ce57704e0b8a19e929dbf73e
> 2) Fix for readdir not listing full directory entries after an fsstress run
>
> Changes from V3:
> 1) Makefiles are modified so that this code is compiled only on Linux.
> 2) Replaced vasprintf() with qemu_malloc() followed by sprintf().
> 3) Formatting changes per QEMU coding standards.
> 4) Folded bug fixes to original patches
> c) configure option to enable/disable virtfs
>
>   Changes from V2:
> 1) Added new method for specifying export dir. This new method should be more flexible.
> 2) rebased to qemu master bedd2912c83b1a87a6bfe3f59a892fd65cda7084
>
> Changes from V1:
> 1) fsstress test suite runs successfully with the patches. That should indicate
>      patches are stable enough to be merged.
> 2) Added proper error handling to all posix_* calls.
> 3) Fixed code to follow Qemu coding style.
> 4) Other bug fixes most of which are folded back into the original patches
> 5) rebased to qemu master 0aef4261ac0ec9089ade0e3a92f986cb4ba7317e
>
> Performance details:
>
> # Host
>
>      * 3650M2
>      * 16 CPU, 32 GB RAM
>      * 28 JBOD disks (18G each)
>      * DM striped to make a single 400GB disk/filesystem
>      * 400 GB ext3 filesystem exported/serving data in the host
>      * RHEL5.5, QEMU + 9p Server patches
>
> # Guest
>
>      * 1 vCPU, 4GB memory
>      * virtio network access for CIFS, NFS
>      * virtio transport for virtfs mount
>      * 2.6.33-rc8 + v9 fixes (either on mainline or on 9p-devel list)
>
> # Tests:
>
>      * Created 16 20-GB files on the filesystem
>      * Guest mounts filesystem through v9 (virtio), NFS (virtio), CIFS (virtio)
>      * Perform sequential read and sequential write tests on these 16 20-GB files from the guest
>      * Repeat the tests with various threads/processes (dd) counts
>      * Between each test host and guest unmounts and mounts the filesystem to eliminate any caching affects.
>
> # read tests (sample):
> for i in 1 2 3 4 5 6 7 8 do; time dd of=/dev/null if=./file$i bs=2M count=10240&  ; done
>
> #of Threads  |  1          2         4         8
> ----------------------------------------------------
> VirtFs(MB/S) |  172        170       168       162
> CIFS(MB/S)   |  10         12        22        35
> NFS(MB/S)    |  80         70        62        42
>
> # write tests (sample):
> for i in 1 2 3 4 5 6 7 8 do; time dd if=/dev/zero of=./file$i bs=2M count=10240&  ; done
>
> #of Threads  |  1          2         4          8
> -------------------------------------------------------
> VirtFs(MB/S) |  190        182       150       138
> CIFS(MB/S)   |  30         38        78        100
> NFS(MB/S)    |  35         35        38        37
>
>
> -aneesh
>
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