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Replace the futex hash buckects with Once to fix the leak

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Zhang Junyang 2024-06-22 13:35:23 +00:00 committed by Tate, Hongliang Tian
parent 36841c50d4
commit 6b17cceacc
2 changed files with 24 additions and 10 deletions
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1
kernel/aster-nix/src/process/mod.rs
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@ -35,4 +35,5 @@ pub use wait::{wait_child_exit, WaitOptions};
pub(super) fn init() { pub(super) fn init() {
process::init(); process::init();
posix_thread::futex::init();
} }

33
kernel/aster-nix/src/process/posix_thread/futex.rs
View File

@ -5,6 +5,7 @@
use core::sync::atomic::{AtomicBool, Ordering}; use core::sync::atomic::{AtomicBool, Ordering};
use aster_frame::cpu::num_cpus; use aster_frame::cpu::num_cpus;
use spin::Once;
use crate::{ use crate::{
prelude::*, prelude::*,
@ -36,7 +37,7 @@ pub fn futex_wait_bitset(
futex_addr, futex_val, timeout, bitset futex_addr, futex_val, timeout, bitset
); );
let futex_key = FutexKey::new(futex_addr); let futex_key = FutexKey::new(futex_addr);
let (_, futex_bucket_ref) = FUTEX_BUCKETS.get_bucket(futex_key); let (_, futex_bucket_ref) = get_futex_bucket(futex_key);
// lock futex bucket ref here to avoid data race // lock futex bucket ref here to avoid data race
let mut futex_bucket = futex_bucket_ref.lock(); let mut futex_bucket = futex_bucket_ref.lock();
@ -72,7 +73,7 @@ pub fn futex_wake_bitset(
); );
let futex_key = FutexKey::new(futex_addr); let futex_key = FutexKey::new(futex_addr);
let (_, futex_bucket_ref) = FUTEX_BUCKETS.get_bucket(futex_key); let (_, futex_bucket_ref) = get_futex_bucket(futex_key);
let mut futex_bucket = futex_bucket_ref.lock(); let mut futex_bucket = futex_bucket_ref.lock();
let res = futex_bucket.dequeue_and_wake_items(futex_key, max_count, bitset); let res = futex_bucket.dequeue_and_wake_items(futex_key, max_count, bitset);
// debug!("futex wake bitset succeeds, res = {}", res); // debug!("futex wake bitset succeeds, res = {}", res);
@ -96,8 +97,8 @@ pub fn futex_requeue(
let futex_key = FutexKey::new(futex_addr); let futex_key = FutexKey::new(futex_addr);
let futex_new_key = FutexKey::new(futex_new_addr); let futex_new_key = FutexKey::new(futex_new_addr);
let (bucket_idx, futex_bucket_ref) = FUTEX_BUCKETS.get_bucket(futex_key); let (bucket_idx, futex_bucket_ref) = get_futex_bucket(futex_key);
let (new_bucket_idx, futex_new_bucket_ref) = FUTEX_BUCKETS.get_bucket(futex_new_key); let (new_bucket_idx, futex_new_bucket_ref) = get_futex_bucket(futex_new_key);
let nwakes = { let nwakes = {
if bucket_idx == new_bucket_idx { if bucket_idx == new_bucket_idx {
@ -135,11 +136,23 @@ pub fn futex_requeue(
Ok(nwakes) Ok(nwakes)
} }
lazy_static! { static FUTEX_BUCKETS: Once<FutexBucketVec> = Once::new();
// Use the same count as linux kernel to keep the same performance
static ref BUCKET_COUNT: usize = ((1<<8)* num_cpus()).next_power_of_two() as _; /// Get the futex hash bucket count.
static ref BUCKET_MASK: usize = *BUCKET_COUNT - 1; ///
static ref FUTEX_BUCKETS: FutexBucketVec = FutexBucketVec::new(*BUCKET_COUNT); /// This number is calculated the same way as Linux's:
/// <https://github.com/torvalds/linux/blob/master/kernel/futex/core.c>
fn get_bucket_count() -> usize {
((1 << 8) * num_cpus()).next_power_of_two() as usize
}
fn get_futex_bucket(key: FutexKey) -> (usize, FutexBucketRef) {
FUTEX_BUCKETS.get().unwrap().get_bucket(key)
}
/// Initialize the futex system.
pub fn init() {
FUTEX_BUCKETS.call_once(|| FutexBucketVec::new(get_bucket_count()));
} }
#[derive(Debug, Clone)] #[derive(Debug, Clone)]
@ -168,7 +181,7 @@ impl FutexBucketVec {
} }
pub fn get_bucket(&self, key: FutexKey) -> (usize, FutexBucketRef) { pub fn get_bucket(&self, key: FutexKey) -> (usize, FutexBucketRef) {
let index = *BUCKET_MASK & { let index = (self.vec.len() - 1) & {
// The addr is the multiples of 4, so we ignore the last 2 bits // The addr is the multiples of 4, so we ignore the last 2 bits
let addr = key.addr() >> 2; let addr = key.addr() >> 2;
// simple hash // simple hash