Bug 190961
| Summary: | pvclock_gtod_notify invoked frequently leads to extra cpu load | ||
|---|---|---|---|
| Product: | Virtualization | Reporter: | Chen Yu (yu.c.chen) |
| Component: | kvm | Assignee: | virtualization_kvm |
| Status: | RESOLVED PATCH_ALREADY_AVAILABLE | ||
| Severity: | normal | ||
| Priority: | P1 | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Kernel Version: | 4.9 | Subsystem: | |
| Regression: | No | Bisected commit-id: | |
| Bug Depends on: | |||
| Bug Blocks: | 178231 | ||
This thread is created for tracking purpose Currently the notifier of pvclock_gtod_notify() get invoked frequently due to the periodic update_wall_time(). This might slow down the system a little bit as there might be redundant execution code path and unnecessary lock contention in update_pvclock_gtod(), which was found when I was doing suspend/resume speed testings. As pvclock_gtod_notify() should be invoked only when clocksource has changed, according to Commit 16e8d74d2da9 ("KVM: x86: notifier for clocksource changes") , either we can add a new notifier for clocksource switch, or we can simply bypass the following code in pvclock_gtod_notify() earlier if there is no clocksource switch. https://patchwork.kernel.org/patch/9487257/