| Message ID | 20210629152746.2953364-1-nitesh@redhat.com |
|---|---|
| Headers | show |
| Series | genirq: Cleanup the usage of irq_set_affinity_hint | expand |
On Tue, Jun 29, 2021 at 11:28 AM Nitesh Narayan Lal <nitesh@redhat.com> wrote: > > The drivers currently rely on irq_set_affinity_hint() to either set the > affinity_hint that is consumed by the userspace and/or to enforce a custom > affinity. > > irq_set_affinity_hint() as the name suggests is originally introduced to > only set the affinity_hint to help the userspace in guiding the interrupts > and not the affinity itself. However, since the commit > > e2e64a932556 "genirq: Set initial affinity in irq_set_affinity_hint()" > > irq_set_affinity_hint() also started applying the provided cpumask (if not > NULL) as the affinity for the interrupts. The issue that this commit was > trying to solve is to allow the drivers to enforce their affinity mask to > distribute the interrupts across the CPUs such that they don't always end > up on CPU0. This issue has been resolved within the irq subsystem since the > commit > > a0c9259dc4e1 "irq/matrix: Spread interrupts on allocation" > > Hence, there is no need for the drivers to overwrite the affinity to spread > as it is dynamically performed at the time of allocation. > > Also, irq_set_affinity_hint() setting affinity unconditionally introduces > issues for the drivers that only want to set their affinity_hint and not the > affinity itself as for these driver interrupts the default_smp_affinity_mask > is completely ignored (for detailed investigation please refer to [1]). > > Unfortunately reverting the commit e2e64a932556 is not an option at this > point for two reasons [2]: > > - Several drivers for a valid reason (performance) rely on this API to > enforce their affinity mask > > - Until very recently this was the only exported interface that was > available > > To clear this out Thomas has come up with the following interfaces: > > - irq_set_affinity(): only sets affinity of an IRQ [3] > - irq_update_affinity_hint(): Only sets the hint [4] > - irq_set_affinity_and_hint(): Sets both affinity and the hint mask [4] > > The first API is already merged in the linux-next tree and the patch > that introduces the other two interfaces are included with this patch-set. > > To move to the stage where we can safely get rid of the > irq_set_affinity_hint(), which has been marked deprecated, we have to > move all its consumers to these new interfaces. In this patch-set, I have > done that for a few drivers and will hopefully try to move the remaining of > them in the coming days. > > Testing > ------- > In terms of testing, I have performed some basic testing on x86 to verify > things such as the interrupts are evenly spread on all CPUs, hint mask is > correctly set etc. for the drivers - i40e, iavf, mlx5, mlx4, ixgbe, i40iw > and enic on top of: > > git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git > > So more testing is probably required for these and the drivers that I didn't > test and any help will be much appreciated. > > > Notes > ----- > - I was told that i40iw driver is going to be replaced by irdma, however, > the new driver didn't land in Linus's tree yet. Once it does I will send > a follow up patch for that as well. > > - For the mpt3sas driver I decided to go with the usage of > irq_set_affinity_and_hint over irq_set_affinity based on my little > analysis of it and the megaraid driver. However, if we are sure that it > is not required then I can replace it with just irq_set_affinity as one > of its comment suggests. > > > Change from v1 [5] > ------------------ > - Fixed compilation error by adding the new interface definitions for cases > where CONFIG_SMP is not defined > > - Fixed function usage in megaraid_sas and removed unnecessary variable > (Robin Murphy) > > - Removed unwanted #if/endif from mlx4 (Leon Romanovsky) > > - Other indentation related fixes > > > [1] https://lore.kernel.org/lkml/1a044a14-0884-eedb-5d30-28b4bec24b23@redhat.com/ > [2] https://lore.kernel.org/linux-pci/d1d5e797-49ee-4968-88c6-c07119343492@arm.com/ > [3] https://lore.kernel.org/linux-arm-kernel/20210518091725.046774792@linutronix.de/ > [4] https://lore.kernel.org/patchwork/patch/1434326/ > [5] https://lore.kernel.org/linux-scsi/20210617182242.8637-1-nitesh@redhat.com/ > > > Nitesh Narayan Lal (13): > iavf: Use irq_update_affinity_hint > i40e: Use irq_update_affinity_hint > scsi: megaraid_sas: Use irq_set_affinity_and_hint > scsi: mpt3sas: Use irq_set_affinity_and_hint > RDMA/i40iw: Use irq_update_affinity_hint > enic: Use irq_update_affinity_hint > be2net: Use irq_update_affinity_hint > ixgbe: Use irq_update_affinity_hint > mailbox: Use irq_update_affinity_hint > scsi: lpfc: Use irq_set_affinity > hinic: Use irq_set_affinity_and_hint > net/mlx5: Use irq_update_affinity_hint > net/mlx4: Use irq_update_affinity_hint > > Thomas Gleixner (1): > genirq: Provide new interfaces for affinity hints > > drivers/infiniband/hw/i40iw/i40iw_main.c | 4 +- > drivers/mailbox/bcm-flexrm-mailbox.c | 4 +- > drivers/net/ethernet/cisco/enic/enic_main.c | 8 +-- > drivers/net/ethernet/emulex/benet/be_main.c | 4 +- > drivers/net/ethernet/huawei/hinic/hinic_rx.c | 4 +- > drivers/net/ethernet/intel/i40e/i40e_main.c | 8 +-- > drivers/net/ethernet/intel/iavf/iavf_main.c | 8 +-- > drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 10 ++-- > drivers/net/ethernet/mellanox/mlx4/eq.c | 8 ++- > .../net/ethernet/mellanox/mlx5/core/pci_irq.c | 6 +-- > drivers/scsi/lpfc/lpfc_init.c | 4 +- > drivers/scsi/megaraid/megaraid_sas_base.c | 27 +++++----- > drivers/scsi/mpt3sas/mpt3sas_base.c | 21 ++++---- > include/linux/interrupt.h | 53 ++++++++++++++++++- > kernel/irq/manage.c | 8 +-- > 15 files changed, 113 insertions(+), 64 deletions(-) > > -- > > Gentle ping. Any comments or suggestions on any of the patches included in this series? -- Thanks Nitesh
On Thu, Jul 08, 2021 at 03:24:20PM -0400, Nitesh Lal wrote: > On Tue, Jun 29, 2021 at 11:28 AM Nitesh Narayan Lal <nitesh@redhat.com> wrote: <...> > > > > drivers/infiniband/hw/i40iw/i40iw_main.c | 4 +- > > drivers/mailbox/bcm-flexrm-mailbox.c | 4 +- > > drivers/net/ethernet/cisco/enic/enic_main.c | 8 +-- > > drivers/net/ethernet/emulex/benet/be_main.c | 4 +- > > drivers/net/ethernet/huawei/hinic/hinic_rx.c | 4 +- > > drivers/net/ethernet/intel/i40e/i40e_main.c | 8 +-- > > drivers/net/ethernet/intel/iavf/iavf_main.c | 8 +-- > > drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 10 ++-- > > drivers/net/ethernet/mellanox/mlx4/eq.c | 8 ++- > > .../net/ethernet/mellanox/mlx5/core/pci_irq.c | 6 +-- > > drivers/scsi/lpfc/lpfc_init.c | 4 +- > > drivers/scsi/megaraid/megaraid_sas_base.c | 27 +++++----- > > drivers/scsi/mpt3sas/mpt3sas_base.c | 21 ++++---- > > include/linux/interrupt.h | 53 ++++++++++++++++++- > > kernel/irq/manage.c | 8 +-- > > 15 files changed, 113 insertions(+), 64 deletions(-) > > > > -- > > > > > > Gentle ping. > Any comments or suggestions on any of the patches included in this series? Please wait for -rc1, rebase and resend. At least i40iw was deleted during merge window. Thanks > > -- > Thanks > Nitesh >
On Sun, Jul 11, 2021 at 7:32 AM Leon Romanovsky <leonro@nvidia.com> wrote: > > On Thu, Jul 08, 2021 at 03:24:20PM -0400, Nitesh Lal wrote: > > On Tue, Jun 29, 2021 at 11:28 AM Nitesh Narayan Lal <nitesh@redhat.com> wrote: > > <...> > > > > > > > drivers/infiniband/hw/i40iw/i40iw_main.c | 4 +- > > > drivers/mailbox/bcm-flexrm-mailbox.c | 4 +- > > > drivers/net/ethernet/cisco/enic/enic_main.c | 8 +-- > > > drivers/net/ethernet/emulex/benet/be_main.c | 4 +- > > > drivers/net/ethernet/huawei/hinic/hinic_rx.c | 4 +- > > > drivers/net/ethernet/intel/i40e/i40e_main.c | 8 +-- > > > drivers/net/ethernet/intel/iavf/iavf_main.c | 8 +-- > > > drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 10 ++-- > > > drivers/net/ethernet/mellanox/mlx4/eq.c | 8 ++- > > > .../net/ethernet/mellanox/mlx5/core/pci_irq.c | 6 +-- > > > drivers/scsi/lpfc/lpfc_init.c | 4 +- > > > drivers/scsi/megaraid/megaraid_sas_base.c | 27 +++++----- > > > drivers/scsi/mpt3sas/mpt3sas_base.c | 21 ++++---- > > > include/linux/interrupt.h | 53 ++++++++++++++++++- > > > kernel/irq/manage.c | 8 +-- > > > 15 files changed, 113 insertions(+), 64 deletions(-) > > > > > > -- > > > > > > > > > > Gentle ping. > > Any comments or suggestions on any of the patches included in this series? > > Please wait for -rc1, rebase and resend. > At least i40iw was deleted during merge window. > Right, will rebase on top of 5.14-rc1 and resend. -- Thanks Nitesh
Hi Leon, On Sun, Jul 11, 2021 at 7:32 AM Leon Romanovsky <leonro@nvidia.com> wrote: > > On Thu, Jul 08, 2021 at 03:24:20PM -0400, Nitesh Lal wrote: > > On Tue, Jun 29, 2021 at 11:28 AM Nitesh Narayan Lal <nitesh@redhat.com> wrote: > > <...> > > > > > > > drivers/infiniband/hw/i40iw/i40iw_main.c | 4 +- > > > drivers/mailbox/bcm-flexrm-mailbox.c | 4 +- > > > drivers/net/ethernet/cisco/enic/enic_main.c | 8 +-- > > > drivers/net/ethernet/emulex/benet/be_main.c | 4 +- > > > drivers/net/ethernet/huawei/hinic/hinic_rx.c | 4 +- > > > drivers/net/ethernet/intel/i40e/i40e_main.c | 8 +-- > > > drivers/net/ethernet/intel/iavf/iavf_main.c | 8 +-- > > > drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 10 ++-- > > > drivers/net/ethernet/mellanox/mlx4/eq.c | 8 ++- > > > .../net/ethernet/mellanox/mlx5/core/pci_irq.c | 6 +-- > > > drivers/scsi/lpfc/lpfc_init.c | 4 +- > > > drivers/scsi/megaraid/megaraid_sas_base.c | 27 +++++----- > > > drivers/scsi/mpt3sas/mpt3sas_base.c | 21 ++++---- > > > include/linux/interrupt.h | 53 ++++++++++++++++++- > > > kernel/irq/manage.c | 8 +-- > > > 15 files changed, 113 insertions(+), 64 deletions(-) > > > > > > -- > > > > > > > > > > Gentle ping. > > Any comments or suggestions on any of the patches included in this series? > > Please wait for -rc1, rebase and resend. > At least i40iw was deleted during merge window. > In -rc1 some non-trivial mlx5 changes also went in. I was going through these changes and it seems after your patch e4e3f24b822f: ("net/mlx5: Provide cpumask at EQ creation phase") we do want to control the affinity for the mlx5 interrupts from the driver. Is that correct? This would mean that we should use irq_set_affinity_and_hint() instead of irq_update_affinity_hint(). -- Thanks Nitesh
On Mon, Jul 12, 2021 at 05:27:05PM -0400, Nitesh Lal wrote: > Hi Leon, > > On Sun, Jul 11, 2021 at 7:32 AM Leon Romanovsky <leonro@nvidia.com> wrote: > > > > On Thu, Jul 08, 2021 at 03:24:20PM -0400, Nitesh Lal wrote: > > > On Tue, Jun 29, 2021 at 11:28 AM Nitesh Narayan Lal <nitesh@redhat.com> wrote: > > > > <...> > > > > > > > > > > drivers/infiniband/hw/i40iw/i40iw_main.c | 4 +- > > > > drivers/mailbox/bcm-flexrm-mailbox.c | 4 +- > > > > drivers/net/ethernet/cisco/enic/enic_main.c | 8 +-- > > > > drivers/net/ethernet/emulex/benet/be_main.c | 4 +- > > > > drivers/net/ethernet/huawei/hinic/hinic_rx.c | 4 +- > > > > drivers/net/ethernet/intel/i40e/i40e_main.c | 8 +-- > > > > drivers/net/ethernet/intel/iavf/iavf_main.c | 8 +-- > > > > drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 10 ++-- > > > > drivers/net/ethernet/mellanox/mlx4/eq.c | 8 ++- > > > > .../net/ethernet/mellanox/mlx5/core/pci_irq.c | 6 +-- > > > > drivers/scsi/lpfc/lpfc_init.c | 4 +- > > > > drivers/scsi/megaraid/megaraid_sas_base.c | 27 +++++----- > > > > drivers/scsi/mpt3sas/mpt3sas_base.c | 21 ++++---- > > > > include/linux/interrupt.h | 53 ++++++++++++++++++- > > > > kernel/irq/manage.c | 8 +-- > > > > 15 files changed, 113 insertions(+), 64 deletions(-) > > > > > > > > -- > > > > > > > > > > > > > > Gentle ping. > > > Any comments or suggestions on any of the patches included in this series? > > > > Please wait for -rc1, rebase and resend. > > At least i40iw was deleted during merge window. > > > > In -rc1 some non-trivial mlx5 changes also went in. I was going through > these changes and it seems after your patch > > e4e3f24b822f: ("net/mlx5: Provide cpumask at EQ creation phase") > > we do want to control the affinity for the mlx5 interrupts from the driver. > Is that correct? We would like to create devices with correct affinity from the beginning. For this, we will introduce extension to devlink to control affinity that will be used prior initialization sequence. Currently, netdev users who don't want irqbalance are digging into their procfs, reconfigure affinity on already existing devices and hope for the best. This is even more cumbersome for the SIOV use case, where every physical NIC PCI device will/can create thousands of lightweights netdevs that will be forwarded to the containers later. These containers are limited to known CPU cores, so no reason do not limit netdev device too. The same goes for other sub-functions of that PCI device, like RDMA, vdpa e.t.c. > This would mean that we should use irq_set_affinity_and_hint() instead > of irq_update_affinity_hint(). I think so. Thanks > > -- > Thanks > Nitesh >
On Tue, Jul 13, 2021 at 1:01 AM Leon Romanovsky <leon@kernel.org> wrote: > > On Mon, Jul 12, 2021 at 05:27:05PM -0400, Nitesh Lal wrote: > > Hi Leon, > > <snip> > > > > > > > > Gentle ping. > > > > Any comments or suggestions on any of the patches included in this series? > > > > > > Please wait for -rc1, rebase and resend. > > > At least i40iw was deleted during merge window. > > > > > > > In -rc1 some non-trivial mlx5 changes also went in. I was going through > > these changes and it seems after your patch > > > > e4e3f24b822f: ("net/mlx5: Provide cpumask at EQ creation phase") > > > > we do want to control the affinity for the mlx5 interrupts from the driver. > > Is that correct? > > We would like to create devices with correct affinity from the > beginning. For this, we will introduce extension to devlink to control > affinity that will be used prior initialization sequence. > > Currently, netdev users who don't want irqbalance are digging into > their procfs, reconfigure affinity on already existing devices and > hope for the best. > > This is even more cumbersome for the SIOV use case, where every physical > NIC PCI device will/can create thousands of lightweights netdevs that will > be forwarded to the containers later. These containers are limited to known > CPU cores, so no reason do not limit netdev device too. > > The same goes for other sub-functions of that PCI device, like RDMA, > vdpa e.t.c. > > > This would mean that we should use irq_set_affinity_and_hint() instead > > of irq_update_affinity_hint(). > > I think so. > Thanks, will make that change in the patch and re-send. I will also drop your reviewed-by for the mlx5 patch so that you can have a look at it again, please let me know if you have any objections.
The drivers currently rely on irq_set_affinity_hint() to either set the affinity_hint that is consumed by the userspace and/or to enforce a custom affinity. irq_set_affinity_hint() as the name suggests is originally introduced to only set the affinity_hint to help the userspace in guiding the interrupts and not the affinity itself. However, since the commit e2e64a932556 "genirq: Set initial affinity in irq_set_affinity_hint()" irq_set_affinity_hint() also started applying the provided cpumask (if not NULL) as the affinity for the interrupts. The issue that this commit was trying to solve is to allow the drivers to enforce their affinity mask to distribute the interrupts across the CPUs such that they don't always end up on CPU0. This issue has been resolved within the irq subsystem since the commit a0c9259dc4e1 "irq/matrix: Spread interrupts on allocation" Hence, there is no need for the drivers to overwrite the affinity to spread as it is dynamically performed at the time of allocation. Also, irq_set_affinity_hint() setting affinity unconditionally introduces issues for the drivers that only want to set their affinity_hint and not the affinity itself as for these driver interrupts the default_smp_affinity_mask is completely ignored (for detailed investigation please refer to [1]). Unfortunately reverting the commit e2e64a932556 is not an option at this point for two reasons [2]: - Several drivers for a valid reason (performance) rely on this API to enforce their affinity mask - Until very recently this was the only exported interface that was available To clear this out Thomas has come up with the following interfaces: - irq_set_affinity(): only sets affinity of an IRQ [3] - irq_update_affinity_hint(): Only sets the hint [4] - irq_set_affinity_and_hint(): Sets both affinity and the hint mask [4] The first API is already merged in the linux-next tree and the patch that introduces the other two interfaces are included with this patch-set. To move to the stage where we can safely get rid of the irq_set_affinity_hint(), which has been marked deprecated, we have to move all its consumers to these new interfaces. In this patch-set, I have done that for a few drivers and will hopefully try to move the remaining of them in the coming days. Testing ------- In terms of testing, I have performed some basic testing on x86 to verify things such as the interrupts are evenly spread on all CPUs, hint mask is correctly set etc. for the drivers - i40e, iavf, mlx5, mlx4, ixgbe, i40iw and enic on top of: git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git So more testing is probably required for these and the drivers that I didn't test and any help will be much appreciated. Notes ----- - I was told that i40iw driver is going to be replaced by irdma, however, the new driver didn't land in Linus's tree yet. Once it does I will send a follow up patch for that as well. - For the mpt3sas driver I decided to go with the usage of irq_set_affinity_and_hint over irq_set_affinity based on my little analysis of it and the megaraid driver. However, if we are sure that it is not required then I can replace it with just irq_set_affinity as one of its comment suggests. Change from v1 [5] ------------------ - Fixed compilation error by adding the new interface definitions for cases where CONFIG_SMP is not defined - Fixed function usage in megaraid_sas and removed unnecessary variable (Robin Murphy) - Removed unwanted #if/endif from mlx4 (Leon Romanovsky) - Other indentation related fixes [1] https://lore.kernel.org/lkml/1a044a14-0884-eedb-5d30-28b4bec24b23@redhat.com/ [2] https://lore.kernel.org/linux-pci/d1d5e797-49ee-4968-88c6-c07119343492@arm.com/ [3] https://lore.kernel.org/linux-arm-kernel/20210518091725.046774792@linutronix.de/ [4] https://lore.kernel.org/patchwork/patch/1434326/ [5] https://lore.kernel.org/linux-scsi/20210617182242.8637-1-nitesh@redhat.com/ Nitesh Narayan Lal (13): iavf: Use irq_update_affinity_hint i40e: Use irq_update_affinity_hint scsi: megaraid_sas: Use irq_set_affinity_and_hint scsi: mpt3sas: Use irq_set_affinity_and_hint RDMA/i40iw: Use irq_update_affinity_hint enic: Use irq_update_affinity_hint be2net: Use irq_update_affinity_hint ixgbe: Use irq_update_affinity_hint mailbox: Use irq_update_affinity_hint scsi: lpfc: Use irq_set_affinity hinic: Use irq_set_affinity_and_hint net/mlx5: Use irq_update_affinity_hint net/mlx4: Use irq_update_affinity_hint Thomas Gleixner (1): genirq: Provide new interfaces for affinity hints drivers/infiniband/hw/i40iw/i40iw_main.c | 4 +- drivers/mailbox/bcm-flexrm-mailbox.c | 4 +- drivers/net/ethernet/cisco/enic/enic_main.c | 8 +-- drivers/net/ethernet/emulex/benet/be_main.c | 4 +- drivers/net/ethernet/huawei/hinic/hinic_rx.c | 4 +- drivers/net/ethernet/intel/i40e/i40e_main.c | 8 +-- drivers/net/ethernet/intel/iavf/iavf_main.c | 8 +-- drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 10 ++-- drivers/net/ethernet/mellanox/mlx4/eq.c | 8 ++- .../net/ethernet/mellanox/mlx5/core/pci_irq.c | 6 +-- drivers/scsi/lpfc/lpfc_init.c | 4 +- drivers/scsi/megaraid/megaraid_sas_base.c | 27 +++++----- drivers/scsi/mpt3sas/mpt3sas_base.c | 21 ++++---- include/linux/interrupt.h | 53 ++++++++++++++++++- kernel/irq/manage.c | 8 +-- 15 files changed, 113 insertions(+), 64 deletions(-) --