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Revert readv optimization in virtio-net device
The changes introduced in IoVecBufferMut that allowed implementing readv support for virtio-net regressed the performance of vsock device. This is because now, when we create IoVecBufferMut objects we do a bunch (1 memfd_create and 3 mmap) of system calls. virtio-net device avoids the performance issue because it creates a single IoVecBufferMut and re-uses it, whereas vsock is creating a new IoVecBufferMut object for every packet it receives. We have a fix for this, which essentially creates a single IoVecBufferMut that reuses for all the incoming vsock packets during a connection. The problem with the fix is that it makes unit-tests really unhappy and we need a significant amount of work to fix them. So, revert the PR to have main in a clean state. We will fix the vsock issues out-of-band and re-open the PR. This reverts commits: - bc0ba43 - 667aba4 - 5d718d4 - 14e6e33 - 1e4c632 from PR firecracker-microvm#4799 Signed-off-by: Babis Chalios <[email protected]>
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‎resources/seccomp/aarch64-unknown-linux-musl.json‎

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"syscall": "writev",
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"comment": "Used by the VirtIO net device to write to tap"
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},
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{
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"syscall": "readv",
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"comment": "Used by the VirtIO net device to read from tap"
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},
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{
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"syscall": "memfd_create",
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"comment": "Used by the IovDeque implementation"
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},
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{
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"syscall": "fcntl",
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"comment": "Used by the IovDeque implementation",
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"args": [
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{
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"index": 1,
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"type": "dword",
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"op": "eq",
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"val": 1033,
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"comment": "FCNTL_F_SETFD"
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},
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{
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"index": 2,
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"type": "dword",
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"op": "eq",
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"val": 6,
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"comment": "F_SEAL_SHRINK|F_SEAL_GROW"
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}
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]
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},
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{
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"syscall": "fcntl",
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"comment": "Used by the IovDeque implementation",
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"args": [
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{
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"index": 1,
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"type": "dword",
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"op": "eq",
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"val": 1033,
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"comment": "FCNTL_F_SETFD"
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},
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{
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"index": 2,
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"type": "dword",
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"op": "eq",
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"val": 1,
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"comment": "F_SEAL_SEAL"
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}
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]
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},
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{
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"syscall": "mmap",
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"comment": "Used by the IovDeque implementation",
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"args": [
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{
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{
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"index": 2,
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"comment": "PROT_READ|PROT_WRITE"
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},
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{
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"index": 3,
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"type": "dword",
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"op": "eq",
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"val": 17,
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"comment": "MAP_SHARED|MAP_FIXED"
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}
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]
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},
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{
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"syscall": "mmap",
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"comment": "Used by the IovDeque implementation",
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"args": [
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{
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"index": 1,
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"type": "dword",
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{
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"val": 34,
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"comment": "MAP_PRIVATE|MAP_ANONYMOUS"
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}
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]
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},
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{
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"syscall": "fsync"
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},

‎resources/seccomp/x86_64-unknown-linux-musl.json‎

Lines changed: 0 additions & 102 deletions
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"syscall": "writev",
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"comment": "Used by the VirtIO net device to write to tap"
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},
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{
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"syscall": "readv",
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"comment": "Used by the VirtIO net device to read from tap"
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},
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{
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"syscall": "memfd_create",
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"comment": "Used by the IovDeque implementation"
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},
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{
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"syscall": "fcntl",
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"comment": "Used by the IovDeque implementation",
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"args": [
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{
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"index": 1,
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"type": "dword",
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"op": "eq",
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"val": 1033,
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"comment": "FCNTL_F_SETFD"
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},
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{
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"index": 2,
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"type": "dword",
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"op": "eq",
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"val": 6,
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"comment": "F_SEAL_SHRINK|F_SEAL_GROW"
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}
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]
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},
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{
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"syscall": "fcntl",
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"comment": "Used by the IovDeque implementation",
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"args": [
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{
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"index": 1,
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"type": "dword",
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"op": "eq",
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"val": 1033,
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"comment": "FCNTL_F_SETFD"
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},
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{
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"index": 2,
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"type": "dword",
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"op": "eq",
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"val": 1,
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"comment": "F_SEAL_SEAL"
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}
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]
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},
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{
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"syscall": "mmap",
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"comment": "Used by the IovDeque implementation",
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"args": [
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{
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"index": 1,
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"type": "dword",
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"op": "eq",
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"val": 4096,
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"comment": "Page size allocation"
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},
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{
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"index": 2,
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"type": "dword",
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"op": "eq",
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"val": 3,
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"comment": "PROT_READ|PROT_WRITE"
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},
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{
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"index": 3,
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"type": "dword",
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"op": "eq",
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"val": 17,
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"comment": "MAP_SHARED|MAP_FIXED"
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}
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]
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},
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{
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"syscall": "mmap",
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"comment": "Used by the IovDeque implementation",
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"args": [
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{
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"index": 1,
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"type": "dword",
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"op": "eq",
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"val": 8192,
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"comment": "2 pages allocation"
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},
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{
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"index": 2,
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"type": "dword",
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"op": "eq",
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"val": 0,
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"comment": "PROT_NONE"
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},
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{
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"type": "dword",
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"op": "eq",
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"val": 34,
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"comment": "MAP_PRIVATE|MAP_ANONYMOUS"
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}
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]
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},
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{
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"syscall": "fsync"
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},

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