| Message ID | 20240806-isolcpus-io-queues-v3-0-da0eecfeaf8b@suse.de (mailing list archive) |
|---|---|
| Headers | show |
| Series | honor isolcpus configuration | expand |
On Tue, 6 Aug 2024 at 08:10, Daniel Wagner <dwagner@suse.de> wrote: > The only stall I was able to trigger > reliable was with qemu's PCI emulation. It looks like when a CPU is > offlined, the PCI affinity is reprogrammed but qemu still routes IRQs to > an offline CPU instead to newly programmed destination CPU. All worked > fine on real hardware. Hi Daniel, Please file a QEMU bug report here (or just reply to this emails with details on how to reproduce the issue and I'll file the issue on your behalf): https://gitlab.com/qemu-project/qemu/-/issues We can also wait until your Linux patches have landed if that makes it easier to reproduce the bug. Thanks! Stefan
On Tue, Aug 06, 2024 at 09:09:50AM GMT, Stefan Hajnoczi wrote: > On Tue, 6 Aug 2024 at 08:10, Daniel Wagner <dwagner@suse.de> wrote: > > The only stall I was able to trigger > > reliable was with qemu's PCI emulation. It looks like when a CPU is > > offlined, the PCI affinity is reprogrammed but qemu still routes IRQs to > > an offline CPU instead to newly programmed destination CPU. All worked > > fine on real hardware. > > Hi Daniel, > Please file a QEMU bug report here (or just reply to this emails with > details on how to reproduce the issue and I'll file the issue on your > behalf): > https://gitlab.com/qemu-project/qemu/-/issues > > We can also wait until your Linux patches have landed if that makes it > easier to reproduce the bug. Thanks for the offer. I tried simplify the setup and come up with producer using qemu directly instead with libvirt. And now it works just fine. I'll try to figure out what the magic argument...
After the discussion with Ming on managed_irq, I decided to bring back the io_queue option because managed_irq is clearly targetting a different use case and Ming ask not to drop support for his use case. In an offline discussion with Frederic, I learned what the plans are with isolcpus. The future is in cpusets but reconfiguration happens only on offline CPUs. I think this approach will go into this direction. I've digged up Ming's attempt to replace the blk_mq_[pci|virtio]_map_queues a more generic blk_mq_dev_map_queues function which takes callback to ask the driver for an affinity mask for a hardware queue. With this central function in place, it's also simple to overwrite affinities in the core and the drivers don't have to be made aware of isolcpus configurations. The original attempt was to update the nvme-pci driver only. Hannes asked me to look into the other multiqueue drivers/devices. Unfortunatly, I don't have all the hardware to test against. So this is only tested with nvme-pci, smartpqi, qla2xxx and megaraid. The testing also involved CPU hotplug events and I was not able to observe any stalls, e.g. with hctx which have online and offline CPUs. The only stall I was able to trigger reliable was with qemu's PCI emulation. It looks like when a CPU is offlined, the PCI affinity is reprogrammed but qemu still routes IRQs to an offline CPU instead to newly programmed destination CPU. All worked fine on real hardware. Finally, I also added a new CPU-hctx mapping function for the isolcpus case. Initially the blk_mq_map_queues function was used but it turns out this will map all isol CPUs to the first CPU. The new function first maps the housekeeping CPUs to the right htcx using the existing mapping logic. The isol CPUs are then assigned evenly to the hctxs. I suppose this could be done a bit smarter and also considering NUMA aspects when we agree on this approach. This series is based on linux-block/for-6.12/block. If this is the wrong branch please let me know which one is better suited. Thanks. Initial cover letter: The nvme-pci driver is ignoring the isolcpus configuration. There were several attempts to fix this in the past [1][2]. This is another attempt but this time trying to address the feedback and solve it in the core code. The first patch introduces a new option for isolcpus 'io_queue', but I'm not really sure if this is needed and we could just use the managed_irq option instead. I guess depends if there is an use case which depens on queues on the isolated CPUs. The second patch introduces a new block layer helper which returns the number of possible queues. I suspect it would makes sense also to make this helper a bit smarter and also consider the number of queues the hardware supports. And the last patch updates the group_cpus_evenly function so that it uses only the housekeeping CPUs when they are defined Note this series is not addressing the affinity setting of the admin queue (queue 0). I'd like to address this after we agreed on how to solve this. Currently, the admin queue affinity can be controlled by the irq_afffinity command line option, so there is at least a workaround for it. Baseline: available: 2 nodes (0-1) node 0 cpus: 0 1 2 3 node 0 size: 1536 MB node 0 free: 1227 MB node 1 cpus: 4 5 6 7 node 1 size: 1729 MB node 1 free: 1422 MB node distances: node 0 1 0: 10 20 1: 20 10 options nvme write_queues=4 poll_queues=4 55: 0 41 0 0 0 0 0 0 PCI-MSIX-0000:00:05.0 0-edge nvme0q0 affinity: 0-3 63: 0 0 0 0 0 0 0 0 PCI-MSIX-0000:00:05.0 1-edge nvme0q1 affinity: 4-5 64: 0 0 0 0 0 0 0 0 PCI-MSIX-0000:00:05.0 2-edge nvme0q2 affinity: 6-7 65: 0 0 0 0 0 0 0 0 PCI-MSIX-0000:00:05.0 3-edge nvme0q3 affinity: 0-1 66: 0 0 0 0 0 0 0 0 PCI-MSIX-0000:00:05.0 4-edge nvme0q4 affinity: 2-3 67: 0 0 0 0 24 0 0 0 PCI-MSIX-0000:00:05.0 5-edge nvme0q5 affinity: 4 68: 0 0 0 0 0 1 0 0 PCI-MSIX-0000:00:05.0 6-edge nvme0q6 affinity: 5 69: 0 0 0 0 0 0 41 0 PCI-MSIX-0000:00:05.0 7-edge nvme0q7 affinity: 6 70: 0 0 0 0 0 0 0 3 PCI-MSIX-0000:00:05.0 8-edge nvme0q8 affinity: 7 71: 1 0 0 0 0 0 0 0 PCI-MSIX-0000:00:05.0 9-edge nvme0q9 affinity: 0 72: 0 18 0 0 0 0 0 0 PCI-MSIX-0000:00:05.0 10-edge nvme0q10 affinity: 1 73: 0 0 0 0 0 0 0 0 PCI-MSIX-0000:00:05.0 11-edge nvme0q11 affinity: 2 74: 0 0 0 3 0 0 0 0 PCI-MSIX-0000:00:05.0 12-edge nvme0q12 affinity: 3 queue mapping for /dev/nvme0n1 hctx0: default 4 5 hctx1: default 6 7 hctx2: default 0 1 hctx3: default 2 3 hctx4: read 4 hctx5: read 5 hctx6: read 6 hctx7: read 7 hctx8: read 0 hctx9: read 1 hctx10: read 2 hctx11: read 3 hctx12: poll 4 5 hctx13: poll 6 7 hctx14: poll 0 1 hctx15: poll 2 3 PCI name is 00:05.0: nvme0n1 irq 55, cpu list 0-3, effective list 1 irq 63, cpu list 4-5, effective list 5 irq 64, cpu list 6-7, effective list 7 irq 65, cpu list 0-1, effective list 1 irq 66, cpu list 2-3, effective list 3 irq 67, cpu list 4, effective list 4 irq 68, cpu list 5, effective list 5 irq 69, cpu list 6, effective list 6 irq 70, cpu list 7, effective list 7 irq 71, cpu list 0, effective list 0 irq 72, cpu list 1, effective list 1 irq 73, cpu list 2, effective list 2 irq 74, cpu list 3, effective list 3 * patched: 48: 0 0 33 0 0 0 0 0 PCI-MSIX-0000:00:05.0 0-edge nvme0q0 affinity: 0-3 58: 0 0 0 0 0 0 0 0 PCI-MSIX-0000:00:05.0 1-edge nvme0q1 affinity: 4 59: 0 0 0 0 0 0 0 0 PCI-MSIX-0000:00:05.0 2-edge nvme0q2 affinity: 5 60: 0 0 0 0 0 0 0 0 PCI-MSIX-0000:00:05.0 3-edge nvme0q3 affinity: 0 61: 0 0 0 0 0 0 0 0 PCI-MSIX-0000:00:05.0 4-edge nvme0q4 affinity: 1 62: 0 0 0 0 45 0 0 0 PCI-MSIX-0000:00:05.0 5-edge nvme0q5 affinity: 4 63: 0 0 0 0 0 12 0 0 PCI-MSIX-0000:00:05.0 6-edge nvme0q6 affinity: 5 64: 2 0 0 0 0 0 0 0 PCI-MSIX-0000:00:05.0 7-edge nvme0q7 affinity: 0 65: 0 35 0 0 0 0 0 0 PCI-MSIX-0000:00:05.0 8-edge nvme0q8 affinity: 1 queue mapping for /dev/nvme0n1 hctx0: default 2 3 4 6 7 hctx1: default 5 hctx2: default 0 hctx3: default 1 hctx4: read 4 hctx5: read 5 hctx6: read 0 hctx7: read 1 hctx8: poll 4 hctx9: poll 5 hctx10: poll 0 hctx11: poll 1 PCI name is 00:05.0: nvme0n1 irq 48, cpu list 0-3, effective list 2 irq 58, cpu list 4, effective list 4 irq 59, cpu list 5, effective list 5 irq 60, cpu list 0, effective list 0 irq 61, cpu list 1, effective list 1 irq 62, cpu list 4, effective list 4 irq 63, cpu list 5, effective list 5 irq 64, cpu list 0, effective list 0 irq 65, cpu list 1, effective list 1 [1] https://lore.kernel.org/lkml/20220423054331.GA17823@lst.de/T/#m9939195a465accbf83187caf346167c4242e798d [2] https://lore.kernel.org/linux-nvme/87fruci5nj.ffs@tglx/ Signed-off-by: Daniel Wagner <dwagner@suse.de> --- Changes in v3: - lifted a couple of patches from https://lore.kernel.org/all/20210709081005.421340-1-ming.lei@redhat.com/ "virito: add APIs for retrieving vq affinity" "blk-mq: introduce blk_mq_dev_map_queues" - replaces all users of blk_mq_[pci|virtio]_map_queues with blk_mq_dev_map_queues - updated/extended number of queue calc helpers - add isolcpus=io_queue CPU-hctx mapping function - documented enum hk_type and isolcpus=io_queue - added "scsi: pm8001: do not overwrite PCI queue mapping" - Link to v2: https://lore.kernel.org/r/20240627-isolcpus-io-queues-v2-0-26a32e3c4f75@suse.de Changes in v2: - updated documentation - splitted blk/nvme-pci patch - dropped HK_TYPE_IO_QUEUE, use HK_TYPE_MANAGED_IRQ - Link to v1: https://lore.kernel.org/r/20240621-isolcpus-io-queues-v1-0-8b169bf41083@suse.de --- Daniel Wagner (13): scsi: pm8001: do not overwrite PCI queue mapping scsi: replace blk_mq_pci_map_queues with blk_mq_dev_map_queues nvme: replace blk_mq_pci_map_queues with blk_mq_dev_map_queues virtio: blk/scs: replace blk_mq_virtio_map_queues with blk_mq_dev_map_queues blk-mq: remove unused queue mapping helpers sched/isolation: Add io_queue housekeeping option docs: add io_queue as isolcpus options blk-mq: add number of queue calc helper nvme-pci: use block layer helpers to calculate num of queues scsi: use block layer helpers to calculate num of queues virtio: blk/scsi: use block layer helpers to calculate num of queues lib/group_cpus.c: honor housekeeping config when grouping CPUs blk-mq: use hk cpus only when isolcpus=io_queue is enabled Ming Lei (2): virito: add APIs for retrieving vq affinity blk-mq: introduce blk_mq_dev_map_queues Documentation/admin-guide/kernel-parameters.txt | 9 ++ block/blk-mq-cpumap.c | 136 ++++++++++++++++++++++++ block/blk-mq-pci.c | 41 ++----- block/blk-mq-virtio.c | 46 +++----- drivers/block/virtio_blk.c | 8 +- drivers/nvme/host/pci.c | 8 +- drivers/scsi/fnic/fnic_main.c | 3 +- drivers/scsi/hisi_sas/hisi_sas.h | 1 - drivers/scsi/hisi_sas/hisi_sas_v2_hw.c | 20 ++-- drivers/scsi/hisi_sas/hisi_sas_v3_hw.c | 5 +- drivers/scsi/megaraid/megaraid_sas_base.c | 18 ++-- drivers/scsi/mpi3mr/mpi3mr_os.c | 3 +- drivers/scsi/mpt3sas/mpt3sas_scsih.c | 3 +- drivers/scsi/pm8001/pm8001_init.c | 9 +- drivers/scsi/qla2xxx/qla_isr.c | 10 +- drivers/scsi/qla2xxx/qla_nvme.c | 3 +- drivers/scsi/qla2xxx/qla_os.c | 3 +- drivers/scsi/smartpqi/smartpqi_init.c | 12 +-- drivers/scsi/virtio_scsi.c | 4 +- drivers/virtio/virtio.c | 10 ++ include/linux/blk-mq-pci.h | 7 +- include/linux/blk-mq-virtio.h | 8 +- include/linux/blk-mq.h | 7 ++ include/linux/sched/isolation.h | 15 +++ include/linux/virtio.h | 2 + kernel/sched/isolation.c | 7 ++ lib/group_cpus.c | 75 ++++++++++++- 27 files changed, 350 insertions(+), 123 deletions(-) --- base-commit: f48ada402d2f1e46fa241bcc6725bdde70725e15 change-id: 20240620-isolcpus-io-queues-1a88eb47ff8b Best regards,