mirror of
https://github.com/cloud-hypervisor/cloud-hypervisor.git
synced 2025-02-21 10:52:25 +00:00
virtio-fs: Deprecate the DAX feature
Disable the DAX feature from the virtio-fs implementation as the feature is still not stable. The feature is deprecated, meaning the 'dax' parameter will be removed in about 2 releases cycles. In the meantime, the parameter value is ignored and forced to be disabled. Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This commit is contained in:
Sebastien Boeuf
Bo Chen
parent
fd40aceabb
commit
afd9f17b73
33
docs/fs.md
33
docs/fs.md
@ -74,24 +74,6 @@ system, here is the Cloud Hypervisor command you need to run:
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--fs tag=myfs,socket=/tmp/virtiofs,num_queues=1,queue_size=512
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```
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By default, DAX is enabled with a cache window of 8GiB. You can specify a custom
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size (let's say 4GiB for this example) for the cache by explicitly setting DAX
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and the cache size:
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```bash
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--fs tag=myfs,socket=/tmp/virtiofs,num_queues=1,queue_size=512,dax=on,cache_size=4G
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```
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In case you don't want to use a shared window of cache to pass the shared files
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content, this means you will have to explicitly disable DAX with `dax=off`.
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Note that in this case, the `cache_size` parameter will be ignored.
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```bash
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--fs tag=myfs,socket=/tmp/virtiofs,num_queues=1,queue_size=512,dax=off
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```
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### Mount the shared directory
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The last step is to mount the shared directory inside the guest, using the
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@ -99,20 +81,13 @@ The last step is to mount the shared directory inside the guest, using the
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```bash
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mkdir mount_dir
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mount -t virtiofs -o dax myfs mount_dir/
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mount -t virtiofs myfs mount_dir/
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```
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The `tag` needs to be consistent with what has been provided through the
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Cloud Hypervisor command line, which happens to be `myfs` in this example.
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The `-o dax` option must be removed in case the shared cache region is not
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enabled from the VMM.
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## DAX feature
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The filesystem should be mounted with `dax` by default as it bypasses the guest
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page cache, reducing the footprint on host memory. When running multiple virtual
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machines on the same host, this will let the host deal with page cache, which
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will increase the density of virtual machines which can be launched.
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When the filesystem is not mounted with the `dax` option, the guest page cache
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is used, which can result in better performance for the guest's workload at the
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cost of increasing the footprint on host memory.
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Given the DAX feature is not stable yet from a daemon standpoint, it is not
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available in Cloud Hypervisor.
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119
src/main.rs
119
src/main.rs
@ -1258,125 +1258,6 @@ mod unit_tests {
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}"#,
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true,
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),
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(
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vec![
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"cloud-hypervisor", "--kernel", "/path/to/kernel",
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"--memory", "shared=true", "--cpus", "boot=4",
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"--fs",
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"tag=virtiofs1,socket=/path/to/sock1,num_queues=4,queue_size=128,dax=on"
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],
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r#"{
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"kernel": {"path": "/path/to/kernel"},
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"memory" : { "shared": true, "size": 536870912 },
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"cpus": {"boot_vcpus": 4, "max_vcpus": 4},
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"fs": [
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{"tag": "virtiofs1", "socket": "/path/to/sock1", "num_queues": 4, "queue_size": 128}
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]
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}"#,
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true,
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),
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(
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vec![
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"cloud-hypervisor", "--kernel", "/path/to/kernel",
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"--memory", "shared=true", "--cpus", "boot=4",
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"--fs",
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"tag=virtiofs1,socket=/path/to/sock1,num_queues=4,queue_size=128,dax=on"
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],
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r#"{
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"kernel": {"path": "/path/to/kernel"},
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"memory" : { "shared": true, "size": 536870912 },
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"cpus": {"boot_vcpus": 4, "max_vcpus": 4},
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"fs": [
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{"tag": "virtiofs1", "socket": "/path/to/sock1", "num_queues": 4, "queue_size": 128, "dax": true}
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]
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}"#,
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true,
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),
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(
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vec![
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"cloud-hypervisor", "--kernel", "/path/to/kernel",
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"--memory", "shared=true", "--cpus", "boot=4",
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"--fs",
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"tag=virtiofs1,socket=/path/to/sock1,num_queues=4,queue_size=128"
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],
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r#"{
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"kernel": {"path": "/path/to/kernel"},
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"memory" : { "shared": true, "size": 536870912 },
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"cpus": {"boot_vcpus": 4, "max_vcpus": 4},
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"fs": [
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{"tag": "virtiofs1", "socket": "/path/to/sock1", "num_queues": 4, "queue_size": 128, "dax": true}
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]
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}"#,
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true,
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),
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(
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vec![
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"cloud-hypervisor", "--kernel", "/path/to/kernel",
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"--memory", "shared=true", "--cpus", "boot=4",
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"--fs",
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"tag=virtiofs1,socket=/path/to/sock1,num_queues=4,queue_size=128,cache_size=8589934592"
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],
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r#"{
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"kernel": {"path": "/path/to/kernel"},
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"memory" : { "shared": true, "size": 536870912 },
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"cpus": {"boot_vcpus": 4, "max_vcpus": 4},
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"fs": [
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{"tag": "virtiofs1", "socket": "/path/to/sock1", "num_queues": 4, "queue_size": 128}
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]
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}"#,
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true,
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),
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(
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vec![
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"cloud-hypervisor", "--kernel", "/path/to/kernel",
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"--memory", "shared=true", "--cpus", "boot=4",
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"--fs",
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"tag=virtiofs1,socket=/path/to/sock1,num_queues=4,queue_size=128"
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],
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r#"{
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"kernel": {"path": "/path/to/kernel"},
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"memory" : { "shared": true, "size": 536870912 },
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"cpus": {"boot_vcpus": 4, "max_vcpus": 4},
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"fs": [
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{"tag": "virtiofs1", "socket": "/path/to/sock1", "num_queues": 4, "queue_size": 128, "cache_size": 8589934592}
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]
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}"#,
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true,
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),
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(
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vec![
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"cloud-hypervisor", "--kernel", "/path/to/kernel",
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"--memory", "shared=true","--cpus", "boot=4",
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"--fs",
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"tag=virtiofs1,socket=/path/to/sock1,num_queues=4,queue_size=128,cache_size=4294967296"
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],
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r#"{
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"kernel": {"path": "/path/to/kernel"},
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"memory" : { "shared": true, "size": 536870912 },
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"cpus": {"boot_vcpus": 4, "max_vcpus": 4},
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"fs": [
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{"tag": "virtiofs1", "socket": "/path/to/sock1", "num_queues": 4, "queue_size": 128, "cache_size": 4294967296}
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]
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}"#,
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true,
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),
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(
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vec![
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"cloud-hypervisor", "--kernel", "/path/to/kernel",
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"--memory", "shared=true","--cpus", "boot=4",
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"--fs",
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"tag=virtiofs1,socket=/path/to/sock1,num_queues=4,queue_size=128,cache_size=4294967296"
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],
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r#"{
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"kernel": {"path": "/path/to/kernel"},
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"memory" : { "shared": true, "size": 536870912 },
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"cpus": {"boot_vcpus": 4, "max_vcpus": 4},
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"fs": [
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{"tag": "virtiofs1", "socket": "/path/to/sock1", "num_queues": 4, "queue_size": 128}
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]
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}"#,
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false,
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),
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]
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.iter()
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.for_each(|(cli, openapi, equal)| {
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@ -2797,36 +2797,11 @@ mod parallel {
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handle_child_output(r, &output);
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}
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#[test]
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#[cfg(not(feature = "mshv"))]
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fn test_virtio_fs_dax_on_default_cache_size() {
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test_virtio_fs(true, None, "never", &prepare_virtiofsd, false, None)
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}
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#[test]
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#[cfg(not(feature = "mshv"))]
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fn test_virtio_fs_dax_on_cache_size_1_gib() {
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test_virtio_fs(
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true,
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Some(0x4000_0000),
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"never",
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&prepare_virtiofsd,
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false,
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None,
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)
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}
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#[test]
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fn test_virtio_fs_dax_off() {
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test_virtio_fs(false, None, "never", &prepare_virtiofsd, false, None)
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}
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#[test]
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#[cfg(not(feature = "mshv"))]
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fn test_virtio_fs_hotplug_dax_on() {
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test_virtio_fs(true, None, "never", &prepare_virtiofsd, true, None)
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}
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#[test]
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fn test_virtio_fs_hotplug_dax_off() {
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test_virtio_fs(false, None, "never", &prepare_virtiofsd, true, None)
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@ -2835,27 +2810,13 @@ mod parallel {
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#[test]
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#[cfg(not(feature = "mshv"))]
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fn test_virtio_fs_multi_segment_hotplug() {
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test_virtio_fs(
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true,
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Some(0x4000_0000),
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"never",
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&prepare_virtiofsd,
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true,
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Some(15),
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)
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test_virtio_fs(false, None, "never", &prepare_virtiofsd, true, Some(15))
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}
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#[test]
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#[cfg(not(feature = "mshv"))]
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fn test_virtio_fs_multi_segment() {
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test_virtio_fs(
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true,
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Some(0x4000_0000),
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"never",
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&prepare_virtiofsd,
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false,
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Some(15),
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)
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test_virtio_fs(false, None, "never", &prepare_virtiofsd, false, Some(15))
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}
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#[test]
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@ -1530,7 +1530,7 @@ fn default_fsconfig_queue_size() -> u16 {
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}
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fn default_fsconfig_dax() -> bool {
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true
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false
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}
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fn default_fsconfig_cache_size() -> u64 {
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@ -1635,6 +1635,15 @@ impl FsConfig {
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}
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}
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if self.dax {
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// TODO: Remove the dax parameter.
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// Tracked by https://github.com/cloud-hypervisor/cloud-hypervisor/issues/3889
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warn!(
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"The experimental DAX feature is deprecated and will be \
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removed in a future release. A request to enable it is ignored."
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);
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}
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Ok(())
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}
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}
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@ -2395,6 +2395,9 @@ impl DeviceManager {
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None
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};
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// DAX is not supported, we override the config by disabling the option.
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fs_cfg.dax = false;
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if let Some(fs_socket) = fs_cfg.socket.to_str() {
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let cache = if fs_cfg.dax {
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let (cache_base, cache_size) = if let Some((base, size)) = cache_range {
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