On 06.06.2014 14:02, Daniel P. Berrange wrote:
On Fri, Jun 06, 2014 at 01:09:58PM +0200, Michal Privoznik wrote:
A PCI device can be associated with a specific NUMA node. Later, when a guest is pinned to one NUMA node the PCI device can be assigned on different NUMA node. This makes DMA transfers travel across nodes and thus results in suboptimal performance. We should expose the NUMA node locality for PCI devices so management applications can make better decisions.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com> ---
diff --git a/src/node_device/node_device_udev.c b/src/node_device/node_device_udev.c index 9a951d9..8e98ad2 100644 --- a/src/node_device/node_device_udev.c +++ b/src/node_device/node_device_udev.c @@ -493,6 +493,13 @@ static int udevProcessPCI(struct udev_device *device, goto out; }
+ if (udevGetIntSysfsAttr(device, + "numa_node", + &data->pci_dev.numa_node, + 10) == PROPERTY_ERROR) { + goto out;
Will this result in an error if the 'numa_node' file does not exist in sysfs - I wouldn't be suprised if older kernels lack it.
No, if a file doesn't exist PROPERTY_MISSING is returned. PROPERTY_ERROR is returned if the file content can't be parsed as int. BTW: the 'numa_node' file is around since ages: kernel.git $ git describe --contains 81bb0e198 v2.6.21-rc1~80^2 But in order to deal with even older kernels (or those which are not NUMA aware) I'm squashing in this: diff --git a/src/node_device/node_device_udev.c b/src/node_device/node_device_udev.c index 8e98ad2..91fc16f 100644 --- a/src/node_device/node_device_udev.c +++ b/src/node_device/node_device_udev.c @@ -493,11 +493,16 @@ static int udevProcessPCI(struct udev_device *device, goto out; } - if (udevGetIntSysfsAttr(device, + rc = udevGetIntSysfsAttr(device, "numa_node", &data->pci_dev.numa_node, - 10) == PROPERTY_ERROR) { + 10); + if (rc == PROPERTY_ERROR) { goto out; + } else if (rc == PROPERTY_MISSING) { + /* The default value is -1, because it can't be 0 + * as zero is valid node number. */ + data->pci_dev.numa_node = -1; } if (!virPCIGetPhysicalFunction(syspath, &data->pci_dev.physical_function)) and pushing. Thanks. Michal