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swap: vmm-swap in concurrently

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A page fault handling may be executed concurrently during swapping in.

This is the first step of vmm-swap in optimization. At the last step
(https://crrev.com/c/4317028), the background thread executes swapping
in.

BUG=b:265606668
TEST=cargo test -p swap

Change-Id: I42ec6b75485c31c9db26c22aa115b50288951b06
Reviewed-on: https://chromium-review.googlesource.com/c/crosvm/crosvm/+/4314185
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>
Reviewed-by: David Stevens <stevensd@chromium.org>
Commit-Queue: Shin Kawamura <kawasin@google.com>
This commit is contained in:
Shintaro Kawamura 2023-03-07 14:55:36 +09:00 committed by crosvm LUCI
parent c30a6ac4ea
commit 06371af4fa
1 changed files with 40 additions and 36 deletions
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76
swap/src/lib.rs
View file

@ -104,6 +104,10 @@ impl From<&SwapState> for State {
direction: SwapDirection::Out,
..
} => State::SwapOutInProgress,
SwapState::InProgress {
direction: SwapDirection::In,
..
} => State::SwapInInProgress,
SwapState::SwapOutCompleted => State::Active,
SwapState::Failed => State::Failed,
}
@ -547,29 +551,9 @@ fn start_monitoring<'a>(
Ok(page_hander)
}
fn disable_monitoring(
mut page_handler: PageHandler,
uffd_list: &UffdList,
guest_memory: &GuestMemory,
) -> anyhow::Result<usize> {
let mut num_pages = 0;
loop {
let pages = page_handler
.swap_in(uffd_list.main_uffd(), MAX_SWAP_CHUNK_SIZE)
.context("unregister all regions")?;
if pages == 0 {
break;
}
num_pages += pages;
}
let regions = regions_from_guest_memory(guest_memory);
unregister_regions(&regions, uffd_list.get_list()).context("unregister regions")?;
Ok(num_pages)
}
enum SwapDirection {
Out,
// TODO(b/265606668): Add `In` to swap-in concurrently.
In,
}
enum SwapState {
@ -642,6 +626,28 @@ fn monitor_process(
state = SwapState::SwapOutCompleted;
}
}
// TODO(b/265606668): execute swap-in on a background thread.
SwapDirection::In => {
let num_pages = page_handler
.swap_in(uffd_list.main_uffd(), MAX_SWAP_CHUNK_SIZE)
.context("swap in")?;
state_transition.pages += num_pages;
state_transition.time_ms = started_time.elapsed().as_millis();
if num_pages == 0 {
info!(
"swap in all {} pages in {} ms.",
state_transition.pages, state_transition.time_ms
);
page_handler_opt = None;
let regions = regions_from_guest_memory(&guest_memory);
unregister_regions(&regions, uffd_list.get_list())
.context("unregister regions")?;
// Truncate the swap file to hold minimum resources while disabled.
swap_file.set_len(0).context("clear swap file")?;
info!("vmm-swap is disabled.");
state = SwapState::Disabled;
}
}
}
continue;
}
@ -811,23 +817,21 @@ fn monitor_process(
} => {
info!("swap out is aborted.");
}
SwapState::InProgress {
direction: SwapDirection::In,
..
} => {
info!("swap in is in progress.");
continue;
}
_ => {}
}
if let Some(page_handler) = page_handler_opt.take() {
let t0 = std::time::Instant::now();
state_transition.pages =
disable_monitoring(page_handler, &uffd_list, &guest_memory)?;
state_transition.time_ms = t0.elapsed().as_millis();
info!(
"swap in all {} pages in {} ms. swap disabled.",
state_transition.pages, state_transition.time_ms
);
// Truncate the swap file to hold minimum resources while disabled.
swap_file.set_len(0).context("clear swap file")?;
state = SwapState::Disabled;
} else {
error!("swap is already disabled.");
}
state = SwapState::InProgress {
direction: SwapDirection::In,
started_time: std::time::Instant::now(),
};
state_transition = StateTransition::default();
info!("start swapping in.");
}
Command::Exit => {
break 'wait;