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[PATCH v3 00/26] virtiofs dax patches
From: |
Dr. David Alan Gilbert (git) |
Subject: |
[PATCH v3 00/26] virtiofs dax patches |
Date: |
Wed, 28 Apr 2021 12:00:34 +0100 |
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
This series adds support for acceleration of virtiofs via DAX
mapping, using features added in the 5.11 Linux kernel.
DAX originally existed in the kernel for mapping real storage
devices directly into memory, so that reads/writes turn into
reads/writes directly mapped into the storage device.
virtiofs's DAX support is similar; a PCI BAR is exposed on the
virtiofs device corresponding to a DAX 'cache' of a user defined size.
The guest daemon then requests files to be mapped into that cache;
when that happens the virtiofsd sends filedescriptors and commands back
to the QEMU that mmap's those files directly into the memory slot
exposed to kvm. The guest can then directly read/write to the files
exposed by virtiofs by reading/writing into the BAR.
A typical invocation would be:
-device
vhost-user-fs-pci,queue-size=1024,chardev=char0,tag=myfs,cache-size=4G
and then the guest must mount with -o dax
Note that the cache doesn't really take VM up on the host, because
everything placed there is just an mmap of a file, so you can afford
to use quite a large cache size.
Unlike a real DAX device, the cache is a finite size that's
potentially smaller than the underlying filesystem (especially when
mapping granuality is taken into account). Mapping, unmapping and
remapping must take place to juggle files into the cache if it's too
small. Some workloads benefit more than others.
Gotchas:
a) If something else on the host truncates an mmap'd file,
kvm gets rather upset; for this reason it's advised that DAX is
currently only suitable for use on non-shared filesystems.
(This series, with a couple of other patches, is at:
https://gitlab.com/virtio-fs/qemu/-/tree/dgilbert-dax-2021-04-28 )
Dave
v3
Review cleanups
Fix some printf formating issues
Dr. David Alan Gilbert (21):
virtiofs: Fixup printf args
virtiofsd: Don't assume header layout
DAX: vhost-user: Rework slave return values
DAX: libvhost-user: Route slave message payload
DAX: libvhost-user: Allow popping a queue element with bad pointers
DAX subprojects/libvhost-user: Add virtio-fs slave types
DAX: virtio: Add shared memory capability
DAX: virtio-fs: Add cache BAR
DAX: virtio-fs: Add vhost-user slave commands for mapping
DAX: virtio-fs: Fill in slave commands for mapping
DAX: virtiofsd Add cache accessor functions
DAX: virtiofsd: Add setup/remove mappings fuse commands
DAX: virtiofsd: Add setup/remove mapping handlers to passthrough_ll
DAX: virtiofsd: Wire up passthrough_ll's lo_setupmapping
DAX: virtiofsd: route se down to destroy method
DAX: virtiofsd: Perform an unmap on destroy
DAX/unmap: virtiofsd: Add VHOST_USER_SLAVE_FS_IO
DAX/unmap virtiofsd: Add wrappers for VHOST_USER_SLAVE_FS_IO
DAX/unmap virtiofsd: Parse unmappable elements
DAX/unmap virtiofsd: Route unmappable reads
DAX/unmap virtiofsd: route unmappable write to slave command
Stefan Hajnoczi (1):
DAX:virtiofsd: implement FUSE_INIT map_alignment field
Vivek Goyal (4):
DAX: virtiofsd: Make lo_removemapping() work
vhost-user-fs: Extend VhostUserFSSlaveMsg to pass additional info
vhost-user-fs: Implement drop CAP_FSETID functionality
virtiofsd: Ask qemu to drop CAP_FSETID if client asked for it
block/export/vhost-user-blk-server.c | 2 +-
contrib/vhost-user-blk/vhost-user-blk.c | 3 +-
contrib/vhost-user-gpu/vhost-user-gpu.c | 5 +-
contrib/vhost-user-input/main.c | 4 +-
contrib/vhost-user-scsi/vhost-user-scsi.c | 2 +-
docs/interop/vhost-user.rst | 37 ++
hw/virtio/meson.build | 1 +
hw/virtio/trace-events | 6 +
hw/virtio/vhost-backend.c | 6 +-
hw/virtio/vhost-user-fs-pci.c | 32 ++
hw/virtio/vhost-user-fs.c | 395 ++++++++++++++++++++++
hw/virtio/vhost-user.c | 62 +++-
hw/virtio/virtio-pci.c | 20 ++
hw/virtio/virtio-pci.h | 4 +
include/hw/virtio/vhost-backend.h | 2 +-
include/hw/virtio/vhost-user-fs.h | 43 +++
meson.build | 6 +
subprojects/libvhost-user/libvhost-user.c | 113 ++++++-
subprojects/libvhost-user/libvhost-user.h | 57 +++-
tests/vhost-user-bridge.c | 4 +-
tools/virtiofsd/buffer.c | 22 +-
tools/virtiofsd/fuse_common.h | 17 +-
tools/virtiofsd/fuse_lowlevel.c | 92 ++++-
tools/virtiofsd/fuse_lowlevel.h | 78 ++++-
tools/virtiofsd/fuse_virtio.c | 372 ++++++++++++++++----
tools/virtiofsd/passthrough_ll.c | 138 +++++++-
26 files changed, 1393 insertions(+), 130 deletions(-)
--
2.31.1
- [PATCH v3 00/26] virtiofs dax patches,
Dr. David Alan Gilbert (git) <=
- [PATCH v3 01/26] virtiofs: Fixup printf args, Dr. David Alan Gilbert (git), 2021/04/28
- [PATCH v3 03/26] DAX: vhost-user: Rework slave return values, Dr. David Alan Gilbert (git), 2021/04/28
- [PATCH v3 02/26] virtiofsd: Don't assume header layout, Dr. David Alan Gilbert (git), 2021/04/28
- [PATCH v3 04/26] DAX: libvhost-user: Route slave message payload, Dr. David Alan Gilbert (git), 2021/04/28
- [PATCH v3 06/26] DAX subprojects/libvhost-user: Add virtio-fs slave types, Dr. David Alan Gilbert (git), 2021/04/28
- [PATCH v3 08/26] DAX: virtio-fs: Add cache BAR, Dr. David Alan Gilbert (git), 2021/04/28
- [PATCH v3 07/26] DAX: virtio: Add shared memory capability, Dr. David Alan Gilbert (git), 2021/04/28
- [PATCH v3 09/26] DAX: virtio-fs: Add vhost-user slave commands for mapping, Dr. David Alan Gilbert (git), 2021/04/28
- [PATCH v3 05/26] DAX: libvhost-user: Allow popping a queue element with bad pointers, Dr. David Alan Gilbert (git), 2021/04/28