> From: lihuisong (C) [mailto:lihuis...@huawei.com] > Sent: Thursday, 21 March 2024 04.04 > > Hi Moren, > > Thanks for your revew. > > 在 2024/3/20 22:05, Morten Brørup 写道: > >> From: Huisong Li [mailto:lihuis...@huawei.com] > >> Sent: Wednesday, 20 March 2024 11.55 > >> > >> The system-wide CPU latency QoS limit has a positive impact on the idle > >> state selection in cpuidle governor. > >> > >> Linux creates a cpu_dma_latency device under '/dev' directory to obtain the > >> CPU latency QoS limit on system and send the QoS request for userspace. > >> Please see the PM QoS framework in the following link: > >> https://docs.kernel.org/power/pm_qos_interface.html?highlight=qos > >> This feature is supported by kernel-v2.6.25. > >> > >> The deeper the idle state, the lower the power consumption, but the longer > >> the resume time. Some service are delay sensitive and very except the low > >> resume time, like interrupt packet receiving mode. > >> > >> So this series introduce PM QoS interface. > > This looks like a 1:1 wrapper for a Linux kernel feature. > right > > Does Windows or BSD offer something similar? > How do we know Windows or BSD support this similar feature?
Ask Windows experts or research using Google. > The DPDK power lib just work on Linux according to the meson.build under > lib/power. > If they support this features, they can open it. The DPDK power lib currently only works on Linux, yes. But its API should still be designed to be platform agnostic, so the functions can be implemented on other platforms in the future. DPDK is on track to work across multiple platforms, including Windows. We must always consider other platforms, and not design DPDK APIs as if they are for Linux/BSD only. > > > > Furthermore, any high-res timing should use nanoseconds, not microseconds or > milliseconds. > > I realize that the Linux kernel only uses microseconds for these APIs, but > the DPDK API should use nanoseconds. > Nanoseconds is more precise, it's good. > But DPDK API how use nanoseconds as you said the the Linux kernel only > uses microseconds for these APIs. > Kernel interface just know an integer value with microseconds unit. One solution is to expose nanoseconds in the DPDK API, and in the Linux specific implementation convert from/to microseconds. You might also want to add a note to the in-line documentation of the relevant functions that the Linux implementation only uses microsecond resolution.
