On Thu, Jan 14, 2021 at 3:46 PM Anatoly Burakov <anatoly.bura...@intel.com> wrote: > > This patchset proposes a simple API for Ethernet drivers to cause the > CPU to enter a power-optimized state while waiting for packets to > arrive. There are multiple proposed mechanisms to achieve said power > savings: simple frequency scaling, idle loop, and monitoring the Rx > queue for incoming packages. The latter is achieved through cooperation > with the NIC driver that will allow us to know address of wake up event, > and wait for writes on that address. > > On IA, this is achieved through using UMONITOR/UMWAIT instructions. They > are used in their raw opcode form because there is no widespread > compiler support for them yet. Still, the API is made generic enough to > hopefully support other architectures, if they happen to implement > similar instructions. > > To achieve power savings, there is a very simple mechanism used: we're > counting empty polls, and if a certain threshold is reached, we employ > one of the suggested power management schemes automatically, from within > a Rx callback inside the PMD. Once there's traffic again, the empty poll > counter is reset. > > This patchset also introduces a few changes into existing power > management-related intrinsics, namely to provide a native way of waking > up a sleeping core without application being responsible for it, as well > as general robustness improvements. There's quite a bit of locking going > on, but these locks are per-thread and very little (if any) contention > is expected, so the performance impact shouldn't be that bad (and in any > case the locking happens when we're about to sleep anyway). > > Why are we putting it into ethdev as opposed to leaving this up to the > application? Our customers specifically requested a way to do it with > minimal changes to the application code. The current approach allows to > just flip a switch and automatically have power savings. > > Things of note: > > - Only 1:1 core to queue mapping is supported, meaning that each lcore > must at most handle RX on a single queue > - Support 3 type policies. Monitor/Pause/Frequency Scaling > - Power management is enabled per-queue > - The API doesn't extend to other device types > > v17: > - Added exception for ethdev driver-only ABI > - Added memory barriers for monitor/wakeup (Konstantin) > - Fixed compiled issues on non-x86 platforms (hopefully!)
SPDK build is still broken. http://mails.dpdk.org/archives/test-report/2021-January/174840.html ==== 20 line log output for Ubuntu 18.04 (dpdk_compile_spdk): ==== rte_power_pmd_mgmt.c:(.text.experimental+0x1cc): undefined reference to `rte_eth_add_rx_callback' rte_power_pmd_mgmt.c:(.text.experimental+0x1f8): undefined reference to `rte_eth_get_monitor_addr' rte_power_pmd_mgmt.c:(.text.experimental+0x37f): undefined reference to `rte_eth_dev_logtype' /dpdk/build/lib/librte_power.a(librte_power_rte_power_pmd_mgmt.c.o): In function `rte_power_pmd_mgmt_queue_disable': rte_power_pmd_mgmt.c:(.text.experimental+0x42a): undefined reference to `rte_eth_dev_is_valid_port' rte_power_pmd_mgmt.c:(.text.experimental+0x4e7): undefined reference to `rte_eth_remove_rx_callback' rte_power_pmd_mgmt.c:(.text.experimental+0x536): undefined reference to `rte_eth_remove_rx_callback' rte_power_pmd_mgmt.c:(.text.experimental+0x54d): undefined reference to `rte_eth_dev_logtype' collect2: error: ld returned 1 exit status /spdk/mk/spdk.app.mk:65: recipe for target 'iscsi_fuzz' failed /spdk/mk/spdk.subdirs.mk:44: recipe for target 'iscsi_fuzz' failed /spdk/mk/spdk.subdirs.mk:44: recipe for target 'fuzz' failed make[4]: *** [iscsi_fuzz] Error 1 make[3]: *** [iscsi_fuzz] Error 2 make[2]: *** [fuzz] Error 2 /spdk/mk/spdk.subdirs.mk:44: recipe for target 'app' failed make[1]: *** [app] Error 2 /spdk/mk/spdk.subdirs.mk:44: recipe for target 'test' failed make: *** [test] Error 2 [2] Error running command. I guess this is because of the added dependency of rte_ethdev to rte_power. Afaics, SPDK does not use pkg-config: https://github.com/spdk/spdk/blob/master/lib/env_dpdk/env.mk#L53 -- David Marchand
