| Message ID | 20220114004358.299534-1-idan.horowitz@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/2] softmmu/cpus: Check if the cpu work list is empty atomically | expand |
On 1/14/22 11:43 AM, Idan Horowitz wrote: > Instead of taking the lock of the cpu work list in order to check if it's > empty, we can just read the head pointer atomically. This decreases > cpu_work_list_empty's share from 5% to 1.3% in a profile of icount-enabled > aarch64-softmmu. > > Signed-off-by: Idan Horowitz<idan.horowitz@gmail.com> > --- > softmmu/cpus.c | 7 +------ > 1 file changed, 1 insertion(+), 6 deletions(-) Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Queued to tcg-next. r~
diff --git a/softmmu/cpus.c b/softmmu/cpus.c index 23bca46b07..035395ae13 100644 --- a/softmmu/cpus.c +++ b/softmmu/cpus.c @@ -73,12 +73,7 @@ bool cpu_is_stopped(CPUState *cpu) bool cpu_work_list_empty(CPUState *cpu) { - bool ret; - - qemu_mutex_lock(&cpu->work_mutex); - ret = QSIMPLEQ_EMPTY(&cpu->work_list); - qemu_mutex_unlock(&cpu->work_mutex); - return ret; + return QSIMPLEQ_EMPTY_ATOMIC(&cpu->work_list); } bool cpu_thread_is_idle(CPUState *cpu)
Instead of taking the lock of the cpu work list in order to check if it's empty, we can just read the head pointer atomically. This decreases cpu_work_list_empty's share from 5% to 1.3% in a profile of icount-enabled aarch64-softmmu. Signed-off-by: Idan Horowitz <idan.horowitz@gmail.com> --- softmmu/cpus.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-)