| Message ID | cover.1610635488.git.anatoly.burakov@intel.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Add PMD power management | expand |
On Thu, Jan 14, 2021 at 3:46 PM Anatoly Burakov <anatoly.burakov@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
On 18-Jan-21 3:24 PM, David Marchand wrote: > On Thu, Jan 14, 2021 at 3:46 PM Anatoly Burakov > <anatoly.burakov@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 > > Sooo... this is an SPDK issue then? Because i can't see any way of fixing the issue on DPDK side.
18/01/2021 16:45, Burakov, Anatoly: > On 18-Jan-21 3:24 PM, David Marchand wrote: > > On Thu, Jan 14, 2021 at 3:46 PM Anatoly Burakov > > <anatoly.burakov@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. [...] > >> 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. The customer laziness is usually a bad justification :) I think we could achieve the same with not too much code on application side. And I'm not sure hiding queue management is sane. Remember this rule: application must remain in control. [...] > > SPDK build is still broken. > > http://mails.dpdk.org/archives/test-report/2021-January/174840.html [...] > > 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 > > Sooo... this is an SPDK issue then? Because i can't see any way of > fixing the issue on DPDK side. Yes SPDK should not skip pkg-config. But it raises 2 question: - are we breaking ABI compatibility? - is ethdev management expected for librte_power? It makes me wonder whether we should host the few functions mixing librte_ethdev and librte_power somewhere else. The question is where?
On 18-Jan-21 4:06 PM, Thomas Monjalon wrote: > 18/01/2021 16:45, Burakov, Anatoly: >> On 18-Jan-21 3:24 PM, David Marchand wrote: >>> On Thu, Jan 14, 2021 at 3:46 PM Anatoly Burakov >>> <anatoly.burakov@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. > [...] >>>> 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. > > The customer laziness is usually a bad justification :) > I think we could achieve the same with not too much code > on application side. Yes, we could. Customers could basically take this patch and reimplement it inside their application, and get the same benefits (with also added benefit of having knowledge about their queue/core mapping, and so being able to use the PAUSE or SCALE schemes for more than one queue). However, i still think it's a valid use case - if we can do it that way and have a ready-made power management story, why not? > And I'm not sure hiding queue management is sane. > Remember this rule: application must remain in control. > The application can still be in control by just not using the API and implementing things manually instead. Nothing is being taken away from the ability of application to be in control. > [...] >>> SPDK build is still broken. >>> http://mails.dpdk.org/archives/test-report/2021-January/174840.html > [...] >>> 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 >> >> Sooo... this is an SPDK issue then? Because i can't see any way of >> fixing the issue on DPDK side. > > Yes SPDK should not skip pkg-config. > But it raises 2 question: > - are we breaking ABI compatibility? Good question. Does including an extra intra-DPDK dependency count as ABI break? I was under impression that we didn't want DPDK to be distributed as individual libraries but rather would like it to be used as a whole, so if internal dependencies between components change, it's not a big deal (unless a third-party build system is used that explicitly specifies dependencies rather than using pkg-config). > - is ethdev management expected for librte_power? > > It makes me wonder whether we should host the few functions mixing > librte_ethdev and librte_power somewhere else. > The question is where? > That could be another possibility. We could put this into a separate library, but IMO it would serve no purpose other than avoiding adding a dependency on *internal* component to librte_power. I'm not sure it's a worthy trade off.
On Mon, Jan 18, 2021 at 6:02 PM Burakov, Anatoly <anatoly.burakov@intel.com> wrote: > >>> SPDK build is still broken. > >>> http://mails.dpdk.org/archives/test-report/2021-January/174840.html > > [...] > >>> 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 > >> > >> Sooo... this is an SPDK issue then? Because i can't see any way of > >> fixing the issue on DPDK side. > > > > Yes SPDK should not skip pkg-config. > > But it raises 2 question: > > - are we breaking ABI compatibility? > > Good question. Does including an extra intra-DPDK dependency count as > ABI break? I was under impression that we didn't want DPDK to be > distributed as individual libraries but rather would like it to be used > as a whole, so if internal dependencies between components change, it's > not a big deal (unless a third-party build system is used that > explicitly specifies dependencies rather than using pkg-config). I don't get where an ABI breakage would be. What I reported is an issue with static link. For shared link, I would expect librte_power would expose its dependency on rte_ethdev via a DT_NEEDED entry. The final binary does not have to be aware of it.
14/01/2021 15:46, Anatoly Burakov: > Anatoly Burakov (5): > eal: uninline power intrinsics > eal: avoid invalid API usage in power intrinsics > eal: change API of power intrinsics > eal: remove sync version of power monitor > eal: add monitor wakeup function > > Liang Ma (6): > ethdev: add simple power management API > power: add PMD power management API and callback > net/ixgbe: implement power management API > net/i40e: implement power management API > net/ice: implement power management API > examples/l3fwd-power: enable PMD power mgmt The librte_power part may deserve another iteration. I suggest to give it a chance for a better version in -rc2. For 21.02-rc1, the EAL and ethdev (including PMDs) parts are merged, thanks.
On 18-Jan-21 10:52 PM, Thomas Monjalon wrote: > 14/01/2021 15:46, Anatoly Burakov: >> Anatoly Burakov (5): >> eal: uninline power intrinsics >> eal: avoid invalid API usage in power intrinsics >> eal: change API of power intrinsics >> eal: remove sync version of power monitor >> eal: add monitor wakeup function >> >> Liang Ma (6): >> ethdev: add simple power management API >> power: add PMD power management API and callback >> net/ixgbe: implement power management API >> net/i40e: implement power management API >> net/ice: implement power management API >> examples/l3fwd-power: enable PMD power mgmt > > The librte_power part may deserve another iteration. > I suggest to give it a chance for a better version in -rc2. > > For 21.02-rc1, the EAL and ethdev (including PMDs) parts are merged, thanks. > Good to hear, thanks! I'll get on the respin of remaining parts.