starred/qemu
1
0
Fork 0
mirror of https://github.com/qemu/qemu.git synced 2026-05-18 02:12:22 +00:00
Code Issues 380 Packages Projects Releases Wiki Activity

rust/hpet: Borrow HPETState.regs once in HPETState::post_load()

Browse Source 
Timers in post_load() access the same HPETState, which is the "self"
HPETState.

So there's no need to access HPETState from child HPETTimer again and
again. Instead, just cache and borrow HPETState.regs at the beginning,
and this could save some CPU cycles and reduce borrow() calls.

It's safe, because post_load() is called with BQL protection, so that
there's no other chance to modify the regs.

Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20251113051937.4017675-15-zhao1.liu@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Zhao Liu
2025-11-13 13:19:29 +08:00
committed by Paolo Bonzini
parent 2abee243d6
commit e3b5a1190a
1 changed files with 4 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
rust/hw/timer/hpet/src/device.rs
View File

@@ -882,9 +882,11 @@ impl HPETState {
}
fn post_load(&self, _version_id: u8) -> Result<(), migration::Infallible> {
let regs = self.regs.borrow();
for timer in self.timers.iter().take(self.num_timers) {
let mut t = timer.borrow_mut();
let cnt = t.get_state().regs.borrow().counter;
let cnt = regs.counter;
t.cmp64 = t.calculate_cmp64(cnt, t.regs.cmp);
t.last = CLOCK_VIRTUAL.get_ns() - NANOSECONDS_PER_SECOND;
@@ -893,7 +895,7 @@ impl HPETState {
// Recalculate the offset between the main counter and guest time
if !self.hpet_offset_saved {
self.hpet_offset
.set(ticks_to_ns(self.regs.borrow().counter) - CLOCK_VIRTUAL.get_ns());
.set(ticks_to_ns(regs.counter) - CLOCK_VIRTUAL.get_ns());
}
Ok(())