| Message ID | 1478905725-219032-1-git-send-email-jonathan.derrick@intel.com |
|---|---|
| State | Accepted |
| Headers | show |
On Fri, Nov 11, 2016 at 04:08:45PM -0700, Jon Derrick wrote: > SRCU lets synchronize_srcu depend on VMD-local RCU primitives, > preventing long delays from locking up RCU in other systems. VMD > performs a synchronize when removing a device, but will hit all irq > lists if the device uses all VMD vectors. This patch will not help VMD's > RCU synchronization, but will isolate the read side delays to the VMD > subsystem. Additionally, the use of SRCU in VMD's isr will keep it > isolated from any other RCU waiters in the rest of the system. Looks good. Reviewed-by: Keith Busch <keith.busch@intel.com> -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, Nov 11, 2016 at 04:08:45PM -0700, Jon Derrick wrote: > SRCU lets synchronize_srcu depend on VMD-local RCU primitives, > preventing long delays from locking up RCU in other systems. VMD > performs a synchronize when removing a device, but will hit all irq > lists if the device uses all VMD vectors. This patch will not help VMD's > RCU synchronization, but will isolate the read side delays to the VMD > subsystem. Additionally, the use of SRCU in VMD's isr will keep it > isolated from any other RCU waiters in the rest of the system. > > The patch was tested using concurrent fio and nvme resets: > [global] > rw=read > bs=4k > direct=1 > ioengine=libaio > iodepth=32 > norandommap > timeout=300 > runtime=1000000000 > > [nvme0] > cpus_allowed=0-63 > numjobs=8 > filename=/dev/nvme0n1 > > [nvme1] > cpus_allowed=0-63 > numjobs=8 > filename=/dev/nvme1n1 > > while (true) do > for i in /sys/class/nvme/nvme*; do > echo "Resetting ${i##*/}" > echo 1 > $i/reset_controller; > sleep 5 > done; > done > > Signed-off-by: Jon Derrick <jonathan.derrick@intel.com> Applied with Keith's reviewed-by to pci/host-vmd for v4.10, thanks! > --- > v1->v2: Kconfig depends on SRCU > > drivers/pci/host/Kconfig | 2 +- > drivers/pci/host/vmd.c | 26 ++++++++++++++++++++------ > 2 files changed, 21 insertions(+), 7 deletions(-) > > diff --git a/drivers/pci/host/Kconfig b/drivers/pci/host/Kconfig > index d7e7c0a..e020359 100644 > --- a/drivers/pci/host/Kconfig > +++ b/drivers/pci/host/Kconfig > @@ -286,7 +286,7 @@ config PCIE_ROCKCHIP > 4 slots. > > config VMD > - depends on PCI_MSI && X86_64 > + depends on PCI_MSI && X86_64 && SRCU > tristate "Intel Volume Management Device Driver" > default N > ---help--- > diff --git a/drivers/pci/host/vmd.c b/drivers/pci/host/vmd.c > index 6614b3552..af4eca2 100644 > --- a/drivers/pci/host/vmd.c > +++ b/drivers/pci/host/vmd.c > @@ -19,6 +19,7 @@ > #include <linux/module.h> > #include <linux/msi.h> > #include <linux/pci.h> > +#include <linux/srcu.h> > #include <linux/rculist.h> > #include <linux/rcupdate.h> > > @@ -39,7 +40,6 @@ > /** > * struct vmd_irq - private data to map driver IRQ to the VMD shared vector > * @node: list item for parent traversal. > - * @rcu: RCU callback item for freeing. > * @irq: back pointer to parent. > * @enabled: true if driver enabled IRQ > * @virq: the virtual IRQ value provided to the requesting driver. > @@ -49,7 +49,6 @@ > */ > struct vmd_irq { > struct list_head node; > - struct rcu_head rcu; > struct vmd_irq_list *irq; > bool enabled; > unsigned int virq; > @@ -58,11 +57,13 @@ struct vmd_irq { > /** > * struct vmd_irq_list - list of driver requested IRQs mapping to a VMD vector > * @irq_list: the list of irq's the VMD one demuxes to. > + * @srcu: SRCU struct for local synchronization. > * @count: number of child IRQs assigned to this vector; used to track > * sharing. > */ > struct vmd_irq_list { > struct list_head irq_list; > + struct srcu_struct srcu; > unsigned int count; > }; > > @@ -224,14 +225,14 @@ static void vmd_msi_free(struct irq_domain *domain, > struct vmd_irq *vmdirq = irq_get_chip_data(virq); > unsigned long flags; > > - synchronize_rcu(); > + synchronize_srcu(&vmdirq->irq->srcu); > > /* XXX: Potential optimization to rebalance */ > raw_spin_lock_irqsave(&list_lock, flags); > vmdirq->irq->count--; > raw_spin_unlock_irqrestore(&list_lock, flags); > > - kfree_rcu(vmdirq, rcu); > + kfree(vmdirq); > } > > static int vmd_msi_prepare(struct irq_domain *domain, struct device *dev, > @@ -646,11 +647,12 @@ static irqreturn_t vmd_irq(int irq, void *data) > { > struct vmd_irq_list *irqs = data; > struct vmd_irq *vmdirq; > + int idx; > > - rcu_read_lock(); > + idx = srcu_read_lock(&irqs->srcu); > list_for_each_entry_rcu(vmdirq, &irqs->irq_list, node) > generic_handle_irq(vmdirq->virq); > - rcu_read_unlock(); > + srcu_read_unlock(&irqs->srcu, idx); > > return IRQ_HANDLED; > } > @@ -696,6 +698,10 @@ static int vmd_probe(struct pci_dev *dev, const struct pci_device_id *id) > return -ENOMEM; > > for (i = 0; i < vmd->msix_count; i++) { > + err = init_srcu_struct(&vmd->irqs[i].srcu); > + if (err) > + return err; > + > INIT_LIST_HEAD(&vmd->irqs[i].irq_list); > err = devm_request_irq(&dev->dev, pci_irq_vector(dev, i), > vmd_irq, 0, "vmd", &vmd->irqs[i]); > @@ -714,11 +720,19 @@ static int vmd_probe(struct pci_dev *dev, const struct pci_device_id *id) > return 0; > } > > +static void vmd_cleanup_srcu(struct vmd_dev *vmd) > +{ > + int i; > + for (i = 0; i < vmd->msix_count; i++) > + cleanup_srcu_struct(&vmd->irqs[i].srcu); > +} > + > static void vmd_remove(struct pci_dev *dev) > { > struct vmd_dev *vmd = pci_get_drvdata(dev); > > vmd_detach_resources(vmd); > + vmd_cleanup_srcu(vmd); > sysfs_remove_link(&vmd->dev->dev.kobj, "domain"); > pci_stop_root_bus(vmd->bus); > pci_remove_root_bus(vmd->bus); > -- > 1.8.3.1 > -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/pci/host/Kconfig b/drivers/pci/host/Kconfig index d7e7c0a..e020359 100644 --- a/drivers/pci/host/Kconfig +++ b/drivers/pci/host/Kconfig @@ -286,7 +286,7 @@ config PCIE_ROCKCHIP 4 slots. config VMD - depends on PCI_MSI && X86_64 + depends on PCI_MSI && X86_64 && SRCU tristate "Intel Volume Management Device Driver" default N ---help--- diff --git a/drivers/pci/host/vmd.c b/drivers/pci/host/vmd.c index 6614b3552..af4eca2 100644 --- a/drivers/pci/host/vmd.c +++ b/drivers/pci/host/vmd.c @@ -19,6 +19,7 @@ #include <linux/module.h> #include <linux/msi.h> #include <linux/pci.h> +#include <linux/srcu.h> #include <linux/rculist.h> #include <linux/rcupdate.h> @@ -39,7 +40,6 @@ /** * struct vmd_irq - private data to map driver IRQ to the VMD shared vector * @node: list item for parent traversal. - * @rcu: RCU callback item for freeing. * @irq: back pointer to parent. * @enabled: true if driver enabled IRQ * @virq: the virtual IRQ value provided to the requesting driver. @@ -49,7 +49,6 @@ */ struct vmd_irq { struct list_head node; - struct rcu_head rcu; struct vmd_irq_list *irq; bool enabled; unsigned int virq; @@ -58,11 +57,13 @@ struct vmd_irq { /** * struct vmd_irq_list - list of driver requested IRQs mapping to a VMD vector * @irq_list: the list of irq's the VMD one demuxes to. + * @srcu: SRCU struct for local synchronization. * @count: number of child IRQs assigned to this vector; used to track * sharing. */ struct vmd_irq_list { struct list_head irq_list; + struct srcu_struct srcu; unsigned int count; }; @@ -224,14 +225,14 @@ static void vmd_msi_free(struct irq_domain *domain, struct vmd_irq *vmdirq = irq_get_chip_data(virq); unsigned long flags; - synchronize_rcu(); + synchronize_srcu(&vmdirq->irq->srcu); /* XXX: Potential optimization to rebalance */ raw_spin_lock_irqsave(&list_lock, flags); vmdirq->irq->count--; raw_spin_unlock_irqrestore(&list_lock, flags); - kfree_rcu(vmdirq, rcu); + kfree(vmdirq); } static int vmd_msi_prepare(struct irq_domain *domain, struct device *dev, @@ -646,11 +647,12 @@ static irqreturn_t vmd_irq(int irq, void *data) { struct vmd_irq_list *irqs = data; struct vmd_irq *vmdirq; + int idx; - rcu_read_lock(); + idx = srcu_read_lock(&irqs->srcu); list_for_each_entry_rcu(vmdirq, &irqs->irq_list, node) generic_handle_irq(vmdirq->virq); - rcu_read_unlock(); + srcu_read_unlock(&irqs->srcu, idx); return IRQ_HANDLED; } @@ -696,6 +698,10 @@ static int vmd_probe(struct pci_dev *dev, const struct pci_device_id *id) return -ENOMEM; for (i = 0; i < vmd->msix_count; i++) { + err = init_srcu_struct(&vmd->irqs[i].srcu); + if (err) + return err; + INIT_LIST_HEAD(&vmd->irqs[i].irq_list); err = devm_request_irq(&dev->dev, pci_irq_vector(dev, i), vmd_irq, 0, "vmd", &vmd->irqs[i]); @@ -714,11 +720,19 @@ static int vmd_probe(struct pci_dev *dev, const struct pci_device_id *id) return 0; } +static void vmd_cleanup_srcu(struct vmd_dev *vmd) +{ + int i; + for (i = 0; i < vmd->msix_count; i++) + cleanup_srcu_struct(&vmd->irqs[i].srcu); +} + static void vmd_remove(struct pci_dev *dev) { struct vmd_dev *vmd = pci_get_drvdata(dev); vmd_detach_resources(vmd); + vmd_cleanup_srcu(vmd); sysfs_remove_link(&vmd->dev->dev.kobj, "domain"); pci_stop_root_bus(vmd->bus); pci_remove_root_bus(vmd->bus);
SRCU lets synchronize_srcu depend on VMD-local RCU primitives, preventing long delays from locking up RCU in other systems. VMD performs a synchronize when removing a device, but will hit all irq lists if the device uses all VMD vectors. This patch will not help VMD's RCU synchronization, but will isolate the read side delays to the VMD subsystem. Additionally, the use of SRCU in VMD's isr will keep it isolated from any other RCU waiters in the rest of the system. The patch was tested using concurrent fio and nvme resets: [global] rw=read bs=4k direct=1 ioengine=libaio iodepth=32 norandommap timeout=300 runtime=1000000000 [nvme0] cpus_allowed=0-63 numjobs=8 filename=/dev/nvme0n1 [nvme1] cpus_allowed=0-63 numjobs=8 filename=/dev/nvme1n1 while (true) do for i in /sys/class/nvme/nvme*; do echo "Resetting ${i##*/}" echo 1 > $i/reset_controller; sleep 5 done; done Signed-off-by: Jon Derrick <jonathan.derrick@intel.com> --- v1->v2: Kconfig depends on SRCU drivers/pci/host/Kconfig | 2 +- drivers/pci/host/vmd.c | 26 ++++++++++++++++++++------ 2 files changed, 21 insertions(+), 7 deletions(-)