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authorKeith Busch <keith.busch@intel.com>2018-05-08 10:00:22 -0600
committerLorenzo Pieralisi <lorenzo.pieralisi@arm.com>2018-06-28 17:25:33 +0100
commita7f58b9ecfd3c0f63703ec10f4a592cc38dbd1b8 (patch)
tree01d129814594762f718149de65d8e3fc2d436455
parentLinux 4.18-rc1 (diff)
downloadlinux-dev-a7f58b9ecfd3c0f63703ec10f4a592cc38dbd1b8.tar.xz
linux-dev-a7f58b9ecfd3c0f63703ec10f4a592cc38dbd1b8.zip
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 <keith.busch@intel.com> [lorenzo.pieralisi@arm.com: changelog] Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Acked-by: Jon Derrick: <jonathan.derrick@intel.com>
-rw-r--r--drivers/pci/controller/vmd.c13
1 files changed, 12 insertions, 1 deletions
diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index 942b64fc7f1f..fd2dbd7eed7b 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)