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[vm] Refine shared chunk expansion

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This commit is contained in:
Shaowei Song 2023-12-19 19:03:37 +08:00 committed by volcano
parent 6c8c8fc871
commit 5efc54cb81
2 changed files with 21 additions and 23 deletions
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39
src/libos/src/vm/shm_manager.rs
View File

@ -103,6 +103,7 @@ impl ShmManager {
.unwrap()
.writeback_file()
.unwrap(),
options.perms(),
),
) {
return Ok(MmapSharedResult::NeedExpand(
@ -192,23 +193,13 @@ impl ShmManager {
Ok(addr)
}
// Replace the given old shared chunk with a new one. The new shared chunk would inherit
// the access and perms from the old one.
pub fn replace_shared_chunk(&mut self, old_shared_chunk: ChunkRef, new_chunk: ChunkRef) {
debug_assert!(old_shared_chunk.is_shared());
let inode_id = {
let mut new_vma = Self::vma_of(&new_chunk);
new_vma.mark_shared();
let new_vma = Self::vma_of(&new_chunk);
let old_vma = Self::vma_of(&old_shared_chunk);
// Inherits access and perms from the old one
new_vma.inherits_access_from(&old_vma);
// Apply higher perms to the whole new range
let new_perms = new_vma.perms();
let old_perms = old_vma.perms();
if new_perms != old_perms {
let perms = new_perms | old_perms;
new_vma.set_perms(perms);
new_vma.modify_permissions_for_committed_pages(perms);
}
let inode_id = Self::inode_id_of(&new_vma);
debug_assert_eq!(inode_id, Self::inode_id_of(&old_vma));
@ -219,24 +210,30 @@ impl ShmManager {
debug_assert!(Arc::ptr_eq(&replaced, &old_shared_chunk));
}
// Left: Old shared vma. Right: New vm range, backed file and offset.
fn can_expand_shared_vma(lhs: &VMArea, rhs: (&VMRange, (&FileRef, usize))) -> bool {
// Left: Old shared vma. Right: New vm range, backed file and offset, perms.
fn can_expand_shared_vma(lhs: &VMArea, rhs: (&VMRange, (&FileRef, usize), &VMPerms)) -> bool {
debug_assert!(lhs.is_shared());
let (lhs_range, lhs_file, lhs_file_offset) = {
let (lhs_range, lhs_file, lhs_file_offset, lhs_perms) = {
let writeback_file = lhs.writeback_file().unwrap();
(lhs.range(), writeback_file.0, writeback_file.1)
(lhs.range(), writeback_file.0, writeback_file.1, lhs.perms())
};
let (rhs_range, (rhs_file, rhs_file_offset)) = rhs;
debug_assert!(lhs_range.end() <= rhs_range.start());
let (rhs_range, (rhs_file, rhs_file_offset), rhs_perms) = rhs;
// The two vm ranges must not be empty, and must be border with each other
if lhs_range.size() == 0 || rhs_range.size() == 0 {
return false;
}
// The two vm range must border with each other
if lhs_range.end() != rhs_range.start() {
return false;
}
// The two vm must have consistent perms
if lhs_perms != *rhs_perms {
return false;
}
// The two vm must have the same backed file and consecutive offset
// within one process
Arc::ptr_eq(lhs_file, rhs_file)
&& rhs_file_offset > lhs_file_offset
&& rhs_file_offset - lhs_file_offset == lhs_range.size()

5
src/libos/src/vm/vm_manager.rs
View File

@ -852,14 +852,15 @@ impl InternalVMManager {
new_chunk
}
// The left chunk is an existing chunk, the right chunk is a newly-created chunk
fn merge_two_single_vma_chunks(&mut self, lhs: &ChunkRef, rhs: &ChunkRef) -> ChunkRef {
let mut new_vma = {
let lhs_vma = lhs.get_vma_for_single_vma_chunk();
let rhs_vma = rhs.get_vma_for_single_vma_chunk();
debug_assert_eq!(lhs_vma.end(), rhs_vma.start());
let mut new_vma = rhs_vma.clone();
new_vma.set_start(lhs_vma.start());
let mut new_vma = lhs_vma.clone();
new_vma.set_end(rhs_vma.end());
new_vma
};