From: Keith Busch Date: Tue, 8 May 2018 16:00:22 +0000 (-0600) Subject: PCI: vmd: White list for fast interrupt handlers X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=a7f58b9ecfd3c0f63703ec10f4a592cc38dbd1b8;p=linux.git PCI: vmd: White list for fast interrupt handlers Devices with slow interrupt handlers are significantly harming performance when their interrupt vector is shared with a fast device. Create a class code white list for devices with known fast interrupt handlers and let all other devices share a single vector so that they don't interfere with performance. At the moment, only the NVM Express class code is on the list, but more may be added if VMD users desire to use other low-latency devices in these domains. Signed-off-by: Keith Busch [lorenzo.pieralisi@arm.com: changelog] Signed-off-by: Lorenzo Pieralisi Acked-by: Jon Derrick: --- diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c index 942b64fc7f1f0..fd2dbd7eed7bc 100644 --- a/drivers/pci/controller/vmd.c +++ b/drivers/pci/controller/vmd.c @@ -197,9 +197,20 @@ static struct vmd_irq_list *vmd_next_irq(struct vmd_dev *vmd, struct msi_desc *d int i, best = 1; unsigned long flags; - if (pci_is_bridge(msi_desc_to_pci_dev(desc)) || vmd->msix_count == 1) + if (vmd->msix_count == 1) return &vmd->irqs[0]; + /* + * White list for fast-interrupt handlers. All others will share the + * "slow" interrupt vector. + */ + switch (msi_desc_to_pci_dev(desc)->class) { + case PCI_CLASS_STORAGE_EXPRESS: + break; + default: + return &vmd->irqs[0]; + } + raw_spin_lock_irqsave(&list_lock, flags); for (i = 1; i < vmd->msix_count; i++) if (vmd->irqs[i].count < vmd->irqs[best].count)