On Thu, Jun 27, 2019 at 12:16:18PM +0000, linmiaohe wrote: > In qemu+shpcp+pcie scene, hotplug a network card(virtio) would take more > than 5 seconds. It's because 5 seconds delayed_work in func > handle_button_press_event with case STATIC_STATE. And this will break some > protocols with timeout within 5 seconds. > It's very nice of you if you could tell me why is 5*HZ there and if this > delay can be reduced? According to Table 2-4 of the PCI Standard Hot-Plug Controller and Subsystem Specification, "System software is waiting 5 seconds to provide the user with an opportunity to cancel the hot-plug operation." (http://drydkim.com/MyDocuments/PCI%20Spec/specifications/shpc1_0.pdf) So the reason the delay can't be reduced or removed is because the spec mandates it. Thanks, Lukas
