Hi Alex, On Wed, 19 Aug 2020 at 19:03, Alexandru Elisei <[email protected]> wrote: > > The series makes the arm_pmu driver use NMIs for the perf interrupt when > NMIs are available on the platform (currently, only arm64 + GICv3). To make > it easier to play with the patches, I've pushed a branch at [1]: > > $ git clone -b pmu-nmi-v6 git://linux-arm.org/linux-ae > > I've tested the series on an espressobin v7*. These are the results of > running perf record -a -- sleep 60: > > 1. Without the patches: > > 16.73% [k] arch_local_irq_enable > 12.20% [k] arch_cpu_idle > 8.61% [k] _raw_spin_unlock_irqrestore > 4.09% [k] arch_local_irq_enable > 2.25% [k] arch_local_irq_enable > 1.82% [k] arch_counter_get_cntpct > [..] > > 2. Using NMIs: > > 3.37% [k] arch_counter_get_cntpct > 2.62% [.] _IO_fwrite > 1.62% [.] __gconv_transform_ascii_internal > 1.49% [.] __mbrtowc > 1.44% [k] el0_svc_common > 1.31% [.] strchr > [..] > > When running perf record -a -- iperf3 -c 127.0.0.1 -t 60: > > 1. Without the patches: > 24.25% [k] __arch_copy_from_user > 20.94% [k] __arch_copy_to_user > 5.71% [k] arch_local_irq_enable > 3.12% [k] _raw_spin_unlock_irqrestore > 2.01% [k] __free_pages_ok > 1.48% [k] arch_cpu_idle > [..] > > 2. Using NMIs: > > 23.15% [k] __arch_copy_from_user > 21.68% [k] __arch_copy_to_user > 1.23% [k] tcp_ack > 1.08% [k] tcp_sendmsg_locked > 0.97% [k] rmqueue > 0.91% [k] __free_pages_ok > [..] > > I've ran the same tests in a VM when both host+guest use NMIs, and when > neither use them. All of these tests were also ran on the model. Similar > results in all cases. > > * All the firmware versions for espressobin v7 that I've tried clear > SCR_EL3.FIQ, which means that NMIs don't work. To make them work on the > board, I modified the GICv3 driver. That's why I would really appreciate > someone testing this series on a board where NMIs work without any GIC > changes.
This series works perfectly fine for me without any GIC changes on Developerbox. FWIW: Tested-by: Sumit Garg <[email protected]> (Developerbox) -Sumit > For people who want to test the series, but don't have a board > with firmware that sets SCR_EL3.FIQ, I've pushed a branch [2] with the > GICv3 drivers changes necessary to make NMIs work: > > $ git clone -b pmu-nmi-v6-nmi-fiq-clear-v2 git://linux-arm.org/linux-ae > > Summary of the patches: > * Patch 1 is a fix for a bug that Julien found during the review for v4. > * Patches 2 and 3 remove locking from arm64 perf event code. > * Patches 4 and 5 makes the arm64 PMU interrupt handler NMI safe. > * Patches 6 and 7 enable the use of NMIs on arm64 with a GICv3 irqchip. > > Changes since v5 [3]: > - Rebased on top of v5.9-rc1. > - Typo fixes. > - Added comments to the ISB added by patches #1 and #2. > - Reworded message for patch #4, as per Mark's excellent suggestion. > > Changes since v4 [4]: > - Rebased on top of v5.8-rc1 and dropped the Tested-by tags because it's > been almost a year since the series has been tested. > - Dropped patch 3 because I couldn't find any instance where > armv7pmu_read_counter() was called with interrupts enabled. I've also > tested this by running several instances of perf for a few hours, and the > function was called every time with interrupts disabled. > - Dropped patches 4 and 5 because the tradeoff wasn't worth it in my > opinion: the irq handler was slower all the time (because it > saved/restored the counter select register), in exchange for being > slightly faster on the rare ocassions when it triggered at the beginning > of the critical sections. > - Minor changes here and there to address review comments. > > Changes since v3 [5]: > - Added tags > - Fix build issue for perf_event_v6 > - Don't disable preemption in pmu->enable() > - Always rely on IPI_IRQ_WORK to run the queued work > - Fixed typos + cleanups > > Changes since v2 [6]: > - Rebased on recent linux-next (next-20190708) > - Fixed a number of bugs with indices (reported by Wei) > - Minor style fixes > > Changes since v1 [7]: > - Rebased on v5.1-rc1 > - Pseudo-NMI has changed a lot since then, use the (now merged) NMI API > - Remove locking from armv7 perf_event > - Use locking only in armv6 perf_event > - Use direct counter/type registers insted of selector register for armv8 > > [1] > http://www.linux-arm.org/git?p=linux-ae.git;a=shortlog;h=refs/heads/pmu-nmi-v6 > [2] > http://www.linux-arm.org/git?p=linux-ae.git;a=shortlog;h=refs/heads/pmu-nmi-v6-nmi-fiq-clear-v2 > [3] https://www.spinics.net/lists/kernel/msg3554236.html > [4] > https://lists.infradead.org/pipermail/linux-arm-kernel/2019-July/666824.html > [5] > https://lists.infradead.org/pipermail/linux-arm-kernel/2019-July/665339.html > [6] > https://lists.infradead.org/pipermail/linux-arm-kernel/2019-March/640536.html > [7] > https://lists.infradead.org/pipermail/linux-arm-kernel/2018-January/554611.html > > Alexandru Elisei (1): > arm64: perf: Add missing ISB in armv8pmu_enable_event() > > Julien Thierry (5): > arm64: perf: Remove PMU locking > arm64: perf: Defer irq_work to IPI_IRQ_WORK > KVM: arm64: pmu: Make overflow handler NMI safe > arm_pmu: Introduce pmu_irq_ops > arm_pmu: arm64: Use NMIs for PMU > > Mark Rutland (1): > arm64: perf: Avoid PMXEV* indirection > > arch/arm64/kernel/perf_event.c | 145 +++++++++++++++++++++------------ > arch/arm64/kvm/pmu-emul.c | 25 +++++- > drivers/perf/arm_pmu.c | 142 +++++++++++++++++++++++++++----- > include/kvm/arm_pmu.h | 1 + > 4 files changed, 241 insertions(+), 72 deletions(-) > > -- > 2.28.0 >
