Every time the vPE is scheduled, the code starts polling the GICR_VPENDBASER.Dirty bit until it becomes 0. It's OK. But the delay_us of the poll function is directly set to 10, which is a long time for most interrupts. In our measurement, it takes only 1~2 microseconds, or even hundreds of nanoseconds, to finish parsing the VPT in most cases. However, in the current implementation, if the GICR_VPENDBASER.Dirty bit is not 0 immediately after the vPE is scheduled, it will directly wait for 10 microseconds, resulting in meaningless waiting.
In order to avoid meaningless waiting, we can set the delay_us to 0, which can exit the poll function immediately when the Dirty bit becomes 0. Signed-off-by: Shenming Lu <lushenm...@huawei.com> --- drivers/irqchip/irq-gic-v3-its.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c index 548de7538632..5cfcf0c2ce1a 100644 --- a/drivers/irqchip/irq-gic-v3-its.c +++ b/drivers/irqchip/irq-gic-v3-its.c @@ -3803,7 +3803,7 @@ static void its_wait_vpt_parse_complete(void) WARN_ON_ONCE(readq_relaxed_poll_timeout_atomic(vlpi_base + GICR_VPENDBASER, val, !(val & GICR_VPENDBASER_Dirty), - 10, 500)); + 0, 500)); } static void its_vpe_schedule(struct its_vpe *vpe) -- 2.19.1