On Thu, Jul 22, 2021 at 12:12:05PM +0100, John Garry wrote: > On 22/07/2021 11:19, Ming Lei wrote: > > > If you check below, you can see that cpu4 services an NVMe irq. From > > > checking htop, during the test that cpu is at 100% load, which I put the > > > performance drop (vs cpu0) down to. > > nvme.poll_queues is 2 in my test, and no irq is involved. But the irq mode > > fio test is still as bad as io_uring. > > > > I tried that: > > dmesg | grep -i nvme > [ 0.000000] Kernel command line: BOOT_IMAGE=/john/Image rdinit=/init > crashkernel=256M@32M console=ttyAMA0,115200 earlycon acpi=force > pcie_aspm=off noinitrd root=/dev/sda1 rw log_buf_len=16M user_debug=1 > iommu.strict=1 nvme.use_threaded_interrupts=0 irqchip.gicv3_pseudo_nmi=1 > nvme.poll_queues=2 > > [ 30.531989] megaraid_sas 0000:08:00.0: NVMe passthru support : Yes > [ 30.615336] megaraid_sas 0000:08:00.0: NVME page size : (4096) > [ 52.035895] nvme 0000:81:00.0: Adding to iommu group 5 > [ 52.047732] nvme nvme0: pci function 0000:81:00.0 > [ 52.067216] nvme nvme0: 22/0/2 default/read/poll queues > [ 52.087318] nvme0n1: p1 > > So I get these results: > cpu0 335K > cpu32 346K > cpu64 300K > cpu96 300K > > So still not massive changes.
In your last email, the results are the following with irq mode io_uring: cpu0 497K cpu4 307K cpu32 566K cpu64 488K cpu96 508K So looks you get much worse result with real io_polling? > > > > Here's some system info: > > > > > > HW queue irq affinities: > > > PCI name is 81:00.0: nvme0n1 > > > -eirq 298, cpu list 67, effective list 67 > > > -eirq 299, cpu list 32-38, effective list 35 > > > -eirq 300, cpu list 39-45, effective list 39 > > > -eirq 301, cpu list 46-51, effective list 46 > > > -eirq 302, cpu list 52-57, effective list 52 > > > -eirq 303, cpu list 58-63, effective list 60 > > > -eirq 304, cpu list 64-69, effective list 68 > > > -eirq 305, cpu list 70-75, effective list 70 > > > -eirq 306, cpu list 76-80, effective list 76 > > > -eirq 307, cpu list 81-85, effective list 84 > > > -eirq 308, cpu list 86-90, effective list 86 > > > -eirq 309, cpu list 91-95, effective list 92 > > > -eirq 310, cpu list 96-101, effective list 100 > > > -eirq 311, cpu list 102-107, effective list 102 > > > -eirq 312, cpu list 108-112, effective list 108 > > > -eirq 313, cpu list 113-117, effective list 116 > > > -eirq 314, cpu list 118-122, effective list 118 > > > -eirq 315, cpu list 123-127, effective list 124 > > > -eirq 316, cpu list 0-5, effective list 4 > > > -eirq 317, cpu list 6-11, effective list 6 > > > -eirq 318, cpu list 12-16, effective list 12 > > > -eirq 319, cpu list 17-21, effective list 20 > > > -eirq 320, cpu list 22-26, effective list 22 > > > -eirq 321, cpu list 27-31, effective list 28 > > > > > > > > > john@ubuntu:~$ lscpu | grep NUMA > > > NUMA node(s): 4 > > > NUMA node0 CPU(s): 0-31 > > > NUMA node1 CPU(s): 32-63 > > > NUMA node2 CPU(s): 64-95 > > > NUMA node3 CPU(s): 96-127 > > > > > > john@ubuntu:~$ lspci | grep -i non > > > 81:00.0 Non-Volatile memory controller: Huawei Technologies Co., Ltd. > > > Device > > > 0123 (rev 45) > > > > > > cat /sys/block/nvme0n1/device/device/numa_node > > > 2 > > BTW, nvme driver doesn't apply the pci numa node, and I guess the > > following patch is needed: > > > > diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c > > index 11779be42186..3c5e10e8b0c2 100644 > > --- a/drivers/nvme/host/core.c > > +++ b/drivers/nvme/host/core.c > > @@ -4366,7 +4366,11 @@ int nvme_init_ctrl(struct nvme_ctrl *ctrl, struct > > device *dev, > > ctrl->dev = dev; > > ctrl->ops = ops; > > ctrl->quirks = quirks; > > +#ifdef CONFIG_NUMA > > + ctrl->numa_node = dev->numa_node; > > +#else > > ctrl->numa_node = NUMA_NO_NODE; > > +#endif > > From a quick look at the code, is this then later set for the PCI device in > nvme_pci_configure_admin_queue()? Yeah, you are right, the pci numa node has been used. > > > INIT_WORK(&ctrl->scan_work, nvme_scan_work); > > INIT_WORK(&ctrl->async_event_work, nvme_async_event_work); > > INIT_WORK(&ctrl->fw_act_work, nvme_fw_act_work); > > > > > [ 52.968495] nvme 0000:81:00.0: Adding to iommu group 5 > > > [ 52.980484] nvme nvme0: pci function 0000:81:00.0 > > > [ 52.999881] nvme nvme0: 23/0/0 default/read/poll queues > > Looks you didn't enabling polling. In irq mode, it isn't strange > > to observe IOPS difference when running fio on different CPUs. > > If you are still keen to investigate more, then can try either of these: > > - add iommu.strict=0 to the cmdline > > - use perf record+annotate to find the hotspot > - For this you need to enable psuedo-NMI with 2x steps: > CONFIG_ARM64_PSEUDO_NMI=y in defconfig > Add irqchip.gicv3_pseudo_nmi=1 > > See > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/Kconfig#n1745 > Your kernel log should show: > [ 0.000000] GICv3: Pseudo-NMIs enabled using forced ICC_PMR_EL1 > synchronisation OK, will try the above tomorrow. > > But my impression is that this may be a HW implementation issue, considering > we don't see such a huge drop off on our HW. Except for mpere-mtjade, we saw bad nvme performance on ThunderX2® CN99XX too, but I don't get one CN99XX system to check if the issue is same with this one. Thanks, Ming _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu