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Optimally divide responsibility for borrow free.

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This appears to slightly improve performance.
This commit is contained in:
4lDO2
2024-09-08 13:04:14 +02:00
parent 031fdea089
commit a0d0eac8aa
3 changed files with 114 additions and 54 deletions
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Cargo.lock
Generated
+1 -1
View File
@@ -227,7 +227,7 @@ checksum = "64072665120942deff5fd5425d6c1811b854f4939e7f1c01ce755f64432bbea7"
[[package]]
name = "redox_syscall"
version = "0.5.3"
version = "0.5.4"
dependencies = [
"bitflags 2.4.2",
]
src/scheme/user.rs
+112 -52
View File
@@ -65,7 +65,7 @@ enum State {
Waiting {
context: Weak<RwSpinlock<Context>>,
fd: Option<Arc<RwLock<FileDescription>>>,
borrowed: PageSpan,
callee_responsible: PageSpan,
canceling: bool,
},
Responded(Response),
@@ -236,9 +236,14 @@ impl UserInner {
u32::try_from(idx).map_err(|_| Error::new(EAGAIN))
}
pub fn call(&self, opcode: Opcode, args: impl Args, borrowed: PageSpan) -> Result<usize> {
pub fn call(
&self,
opcode: Opcode,
args: impl Args,
caller_responsible: &mut PageSpan,
) -> Result<usize> {
let ctx = process::current()?.read().caller_ctx();
match self.call_extended(ctx, None, opcode, args, borrowed)? {
match self.call_extended(ctx, None, opcode, args, caller_responsible)? {
Response::Regular(code, _) => Error::demux(code),
Response::Fd(_) => Err(Error::new(EIO)),
}
@@ -250,7 +255,7 @@ impl UserInner {
fd: Option<Arc<RwLock<FileDescription>>>,
opcode: Opcode,
args: impl Args,
borrowed: PageSpan,
caller_responsible: &mut PageSpan,
) -> Result<Response> {
self.call_extended_inner(
fd,
@@ -266,7 +271,7 @@ impl UserInner {
a
},
},
borrowed,
caller_responsible,
)
}
@@ -274,7 +279,7 @@ impl UserInner {
&self,
fd: Option<Arc<RwLock<FileDescription>>>,
sqe: Sqe,
borrowed: PageSpan,
caller_responsible: &mut PageSpan,
) -> Result<Response> {
if self.unmounting.load(Ordering::SeqCst) {
return Err(Error::new(ENODEV));
@@ -289,7 +294,11 @@ impl UserInner {
context: Arc::downgrade(&current_context),
fd,
canceling: false,
borrowed,
// This is the part that the scheme handler will deallocate when responding. It
// starts as empty, so the caller can unmap it (optimal for TLB), but is populated
// the caller is interrupted by SIGKILL.
callee_responsible: PageSpan::empty(),
};
}
@@ -299,29 +308,44 @@ impl UserInner {
loop {
context::switch();
let eintr_if_sigkill = || {
let mut states = self.states.lock();
let mut eintr_if_sigkill = |callee_responsible: &mut PageSpan| {
// If SIGKILL was found without waiting for scheme, EINTR directly. In that
// case, data loss doesn't matter.
if context::current().read().being_sigkilled {
// EINTR directly if SIGKILL was found without waiting for scheme. Data loss
// doesn't matter.
// Callee must deallocate memory, rather than the caller. This is less optimal
// for TLB, but we don't really have any other choice. The scheme must be able
// to access the borrowed memory until it has responded to the request.
*callee_responsible = core::mem::replace(caller_responsible, PageSpan::empty());
Err(Error::new(EINTR))
} else {
Ok(())
}
};
let mut states = self.states.lock();
match states.get_mut(sqe.tag as usize) {
// invalid state
None => return Err(Error::new(EBADFD)),
Some(o) => match mem::replace(o, State::Placeholder) {
// signal wakeup while awaiting cancelation
old_state @ State::Waiting {
canceling: true, ..
State::Waiting {
canceling: true,
mut callee_responsible,
context,
fd,
} => {
*o = old_state;
let maybe_eintr = eintr_if_sigkill(&mut callee_responsible);
*o = State::Waiting {
canceling: true,
callee_responsible,
context,
fd,
};
drop(states);
eintr_if_sigkill()?;
maybe_eintr?;
context::current().write().block("UserInner::call");
}
// spurious wakeup
@@ -329,17 +353,18 @@ impl UserInner {
canceling: false,
fd,
context,
borrowed,
mut callee_responsible,
} => {
let maybe_eintr = eintr_if_sigkill(&mut callee_responsible);
*o = State::Waiting {
canceling: true,
fd,
context,
borrowed,
callee_responsible,
};
drop(states);
eintr_if_sigkill()?;
maybe_eintr?;
// TODO: Is this too dangerous when the states lock is held?
self.todo.send(Sqe {
@@ -404,10 +429,13 @@ impl UserInner {
},
)?;
let base = dst_page.start_address().data();
let len = buf.len();
Ok(CaptureGuard {
base,
len,
destroyed: false,
base: dst_page.start_address().data(),
len: buf.len(),
head: CopyInfo {
src: Some(tail),
dst: None,
@@ -416,6 +444,11 @@ impl UserInner {
src: None,
dst: None,
},
span: {
let (first_page, page_count, _offset) = page_range_containing(base, len);
PageSpan::new(first_page, page_count)
},
addrsp: Some(dst_addr_space),
})
}
@@ -455,6 +488,8 @@ impl UserInner {
src: None,
dst: None,
},
span: PageSpan::empty(),
addrsp: None,
});
}
@@ -481,6 +516,12 @@ impl UserInner {
src: None,
dst: None,
},
span: {
let (first_page, page_count, _offset) =
page_range_containing(user_buf.addr(), user_buf.len());
PageSpan::new(first_page, page_count)
},
addrsp: Some(dst_space_lock),
});
}
@@ -650,12 +691,18 @@ impl UserInner {
drop(dst_space);
let base = free_span.base.start_address().data() + offset;
Ok(CaptureGuard {
destroyed: false,
base: free_span.base.start_address().data() + offset,
base,
len: user_buf.len(),
head,
tail,
span: {
let (first_page, page_count, _offset) = page_range_containing(base, user_buf.len());
PageSpan::new(first_page, page_count)
},
addrsp: Some(dst_space_lock),
})
}
@@ -1018,7 +1065,7 @@ impl UserInner {
context,
fd,
canceling,
borrowed,
callee_responsible,
} => {
if let Response::Regular(ref mut code, _) = response
&& !canceling
@@ -1044,7 +1091,7 @@ impl UserInner {
}
let unpin = true;
AddrSpace::current()?.munmap(borrowed, unpin)?;
AddrSpace::current()?.munmap(callee_responsible, unpin)?;
}
},
// invalid state
@@ -1158,7 +1205,7 @@ impl UserInner {
],
caller: pid.get() as u64,
},
PageSpan::empty(),
&mut PageSpan::empty(),
)?;
// TODO: I've previously tested that this works, but because the scheme trait all of
@@ -1234,9 +1281,11 @@ pub struct CaptureGuard<const READ: bool, const WRITE: bool> {
destroyed: bool,
base: usize,
len: usize,
span: PageSpan,
head: CopyInfo<READ, WRITE>,
tail: CopyInfo<READ, WRITE>,
addrsp: Option<Arc<AddrSpaceWrapper>>,
}
impl<const READ: bool, const WRITE: bool> CaptureGuard<READ, WRITE> {
fn base(&self) -> usize {
@@ -1245,9 +1294,8 @@ impl<const READ: bool, const WRITE: bool> CaptureGuard<READ, WRITE> {
fn len(&self) -> usize {
self.len
}
fn span(&self) -> PageSpan {
let (first_page, page_count, _offset) = page_range_containing(self.base, self.len);
PageSpan::new(first_page, page_count)
fn span(&mut self) -> &mut PageSpan {
&mut self.span
}
}
struct CopyInfo<const READ: bool, const WRITE: bool> {
@@ -1282,6 +1330,10 @@ impl<const READ: bool, const WRITE: bool> CaptureGuard<READ, WRITE> {
{
dst.copy_from_slice(&src.buf()[..dst.len()])?;
}
let unpin = true;
if let Some(ref addrsp) = self.addrsp {
addrsp.munmap(self.span, unpin)?;
}
Ok(())
}
@@ -1317,7 +1369,7 @@ impl UserScheme {
impl KernelScheme for UserScheme {
fn kopen(&self, path: &str, flags: usize, ctx: CallerCtx) -> Result<OpenResult> {
let inner = self.inner.upgrade().ok_or(Error::new(ENODEV))?;
let address = inner.copy_and_capture_tail(path.as_bytes())?;
let mut address = inner.copy_and_capture_tail(path.as_bytes())?;
match inner.call_extended(
ctx,
None,
@@ -1337,7 +1389,7 @@ impl KernelScheme for UserScheme {
}
fn rmdir(&self, path: &str, _ctx: CallerCtx) -> Result<()> {
let inner = self.inner.upgrade().ok_or(Error::new(ENODEV))?;
let address = inner.copy_and_capture_tail(path.as_bytes())?;
let mut address = inner.copy_and_capture_tail(path.as_bytes())?;
inner.call(
Opcode::Rmdir,
[address.base(), address.len()],
@@ -1348,7 +1400,7 @@ impl KernelScheme for UserScheme {
fn unlink(&self, path: &str, _ctx: CallerCtx) -> Result<()> {
let inner = self.inner.upgrade().ok_or(Error::new(ENODEV))?;
let address = inner.copy_and_capture_tail(path.as_bytes())?;
let mut address = inner.copy_and_capture_tail(path.as_bytes())?;
inner.call(
Opcode::Unlink,
[address.base(), address.len()],
@@ -1363,13 +1415,17 @@ impl KernelScheme for UserScheme {
return Err(Error::new(ESPIPE));
}
inner
.call(Opcode::Fsize, [file], PageSpan::empty())
.call(Opcode::Fsize, [file], &mut PageSpan::empty())
.map(|o| o as u64)
}
fn fchmod(&self, file: usize, mode: u16) -> Result<()> {
let inner = self.inner.upgrade().ok_or(Error::new(ENODEV))?;
inner.call(Opcode::Fchmod, [file, mode as usize], PageSpan::empty())?;
inner.call(
Opcode::Fchmod,
[file, mode as usize],
&mut PageSpan::empty(),
)?;
Ok(())
}
@@ -1388,26 +1444,26 @@ impl KernelScheme for UserScheme {
inner.call(
Opcode::Fchown,
[file, uid as usize, gid as usize],
PageSpan::empty(),
&mut PageSpan::empty(),
)?;
Ok(())
}
fn fcntl(&self, file: usize, cmd: usize, arg: usize) -> Result<usize> {
let inner = self.inner.upgrade().ok_or(Error::new(ENODEV))?;
inner.call(Opcode::Fcntl, [file, cmd, arg], PageSpan::empty())
inner.call(Opcode::Fcntl, [file, cmd, arg], &mut PageSpan::empty())
}
fn fevent(&self, file: usize, flags: EventFlags) -> Result<EventFlags> {
let inner = self.inner.upgrade().ok_or(Error::new(ENODEV))?;
inner
.call(Opcode::Fevent, [file, flags.bits()], PageSpan::empty())
.call(Opcode::Fevent, [file, flags.bits()], &mut PageSpan::empty())
.map(EventFlags::from_bits_truncate)
}
fn frename(&self, file: usize, path: &str, _ctx: CallerCtx) -> Result<()> {
let inner = self.inner.upgrade().ok_or(Error::new(ENODEV))?;
let address = inner.copy_and_capture_tail(path.as_bytes())?;
let mut address = inner.copy_and_capture_tail(path.as_bytes())?;
inner.call(
Opcode::Frename,
[file, address.base(), address.len()],
@@ -1418,24 +1474,24 @@ impl KernelScheme for UserScheme {
fn fsync(&self, file: usize) -> Result<()> {
let inner = self.inner.upgrade().ok_or(Error::new(ENODEV))?;
inner.call(Opcode::Fsync, [file], PageSpan::empty())?;
inner.call(Opcode::Fsync, [file], &mut PageSpan::empty())?;
Ok(())
}
fn ftruncate(&self, file: usize, len: usize) -> Result<()> {
let inner = self.inner.upgrade().ok_or(Error::new(ENODEV))?;
inner.call(Opcode::Ftruncate, [file, len], PageSpan::empty())?;
inner.call(Opcode::Ftruncate, [file, len], &mut PageSpan::empty())?;
Ok(())
}
fn close(&self, file: usize) -> Result<()> {
let inner = self.inner.upgrade().ok_or(Error::new(ENODEV))?;
inner.call(Opcode::Close, [file], PageSpan::empty())?;
inner.call(Opcode::Close, [file], &mut PageSpan::empty())?;
Ok(())
}
fn kdup(&self, file: usize, buf: UserSliceRo, ctx: CallerCtx) -> Result<OpenResult> {
let inner = self.inner.upgrade().ok_or(Error::new(ENODEV))?;
let address = inner.capture_user(buf)?;
let mut address = inner.capture_user(buf)?;
let result = inner.call_extended(
ctx,
None,
@@ -1459,7 +1515,7 @@ impl KernelScheme for UserScheme {
}
fn kfpath(&self, file: usize, buf: UserSliceWo) -> Result<usize> {
let inner = self.inner.upgrade().ok_or(Error::new(ENODEV))?;
let address = inner.capture_user(buf)?;
let mut address = inner.capture_user(buf)?;
let result = inner.call(
Opcode::Fpath,
[file, address.base(), address.len()],
@@ -1482,7 +1538,7 @@ impl KernelScheme for UserScheme {
}
let inner = self.inner.upgrade().ok_or(Error::new(ENODEV))?;
let address = inner.capture_user(buf)?;
let mut address = inner.capture_user(buf)?;
let result = inner.call(
Opcode::Read,
[
@@ -1516,7 +1572,7 @@ impl KernelScheme for UserScheme {
}
let inner = self.inner.upgrade().ok_or(Error::new(ENODEV))?;
let address = inner.capture_user(buf)?;
let mut address = inner.capture_user(buf)?;
let result = inner.call(
Opcode::Write,
[
@@ -1541,11 +1597,15 @@ impl KernelScheme for UserScheme {
if inner.v2 {
return None;
}
Some(inner.call(Opcode::Fsize, [id, pos as usize, whence], PageSpan::empty()))
Some(inner.call(
Opcode::Fsize,
[id, pos as usize, whence],
&mut PageSpan::empty(),
))
}
fn kfutimens(&self, file: usize, buf: UserSliceRo) -> Result<usize> {
let inner = self.inner.upgrade().ok_or(Error::new(ENODEV))?;
let address = inner.capture_user(buf)?;
let mut address = inner.capture_user(buf)?;
let result = inner.call(
Opcode::Futimens,
[file, address.base(), address.len()],
@@ -1557,12 +1617,12 @@ impl KernelScheme for UserScheme {
fn getdents(
&self,
file: usize,
stat: UserSliceWo,
buf: UserSliceWo,
header_size: u16,
opaque_id_start: u64,
) -> Result<usize> {
let inner = self.inner.upgrade().ok_or(Error::new(ENODEV))?;
let address = inner.capture_user(stat)?;
let mut address = inner.capture_user(buf)?;
// TODO: Support passing the 16-byte record_len of the last dent, to make it possible to
// iterate backwards without first interating forward? The last entry will contain the
// opaque id to pass to the next getdents. Since this field is small, this would fit in the
@@ -1583,7 +1643,7 @@ impl KernelScheme for UserScheme {
}
fn kfstat(&self, file: usize, stat: UserSliceWo) -> Result<()> {
let inner = self.inner.upgrade().ok_or(Error::new(ENODEV))?;
let address = inner.capture_user(stat)?;
let mut address = inner.capture_user(stat)?;
let result = inner.call(
Opcode::Fstat,
[file, address.base(), address.len()],
@@ -1594,7 +1654,7 @@ impl KernelScheme for UserScheme {
}
fn kfstatvfs(&self, file: usize, stat: UserSliceWo) -> Result<()> {
let inner = self.inner.upgrade().ok_or(Error::new(ENODEV))?;
let address = inner.capture_user(stat)?;
let mut address = inner.capture_user(stat)?;
let result = inner.call(
Opcode::Fstatvfs,
[file, address.base(), address.len()],
@@ -1623,7 +1683,7 @@ impl KernelScheme for UserScheme {
None,
Opcode::Munmap,
[number, size, flags.bits(), offset],
PageSpan::empty(),
&mut PageSpan::empty(),
)?;
match res {
@@ -1646,7 +1706,7 @@ impl KernelScheme for UserScheme {
Some(desc),
Opcode::Sendfd,
[number, flags.bits()],
PageSpan::empty(),
&mut PageSpan::empty(),
)?;
match res {
syscall
+1 -1
Submodule syscall updated: 4d159ce1c7...c751f76248