Write combining (WC) increases NIC performance by making better
utilization of PCI bus, but cannot be used by all PMDs.
It will be enabled only if RTE_PCI_DRV_WC_ACTIVATE will be set in
drivers flags. For proper work also igb_uio driver must be loaded with
wc_activate set to 1.
When mapping PCI resources, firstly try to us WC.
If it is not supported it will fallback to normal mode.
Signed-off-by: Rafal Kozik <rk@semihalf.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
---
drivers/bus/pci/linux/pci_uio.c | 44 ++++++++++++++++++++++++++++++-----------
drivers/bus/pci/rte_bus_pci.h | 2 ++
2 files changed, 34 insertions(+), 12 deletions(-)
@@ -282,22 +282,19 @@ int
pci_uio_map_resource_by_index(struct rte_pci_device *dev, int res_idx,
struct mapped_pci_resource *uio_res, int map_idx)
{
- int fd;
+ int fd = -1;
char devname[PATH_MAX];
void *mapaddr;
struct rte_pci_addr *loc;
struct pci_map *maps;
+ int wc_activate = 0;
+
+ if (dev->driver != NULL)
+ wc_activate = dev->driver->drv_flags & RTE_PCI_DRV_WC_ACTIVATE;
loc = &dev->addr;
maps = uio_res->maps;
- /* update devname for mmap */
- snprintf(devname, sizeof(devname),
- "%s/" PCI_PRI_FMT "/resource%d",
- rte_pci_get_sysfs_path(),
- loc->domain, loc->bus, loc->devid,
- loc->function, res_idx);
-
/* allocate memory to keep path */
maps[map_idx].path = rte_malloc(NULL, strlen(devname) + 1, 0);
if (maps[map_idx].path == NULL) {
@@ -309,11 +306,34 @@ pci_uio_map_resource_by_index(struct rte_pci_device *dev, int res_idx,
/*
* open resource file, to mmap it
*/
- fd = open(devname, O_RDWR);
- if (fd < 0) {
- RTE_LOG(ERR, EAL, "Cannot open %s: %s\n",
+ if (wc_activate) {
+ /* update devname for mmap */
+ snprintf(devname, sizeof(devname),
+ "%s/" PCI_PRI_FMT "/resource%d_wc",
+ rte_pci_get_sysfs_path(),
+ loc->domain, loc->bus, loc->devid,
+ loc->function, res_idx);
+
+ fd = open(devname, O_RDWR);
+ if (fd >= 0)
+ RTE_LOG(INFO, EAL, "%s mapped\n", devname);
+ }
+
+ if (!wc_activate || fd < 0) {
+ snprintf(devname, sizeof(devname),
+ "%s/" PCI_PRI_FMT "/resource%d",
+ rte_pci_get_sysfs_path(),
+ loc->domain, loc->bus, loc->devid,
+ loc->function, res_idx);
+
+ /* then try to map resource file */
+ fd = open(devname, O_RDWR);
+ if (fd < 0) {
+ RTE_LOG(ERR, EAL, "Cannot open %s: %s\n",
devname, strerror(errno));
- goto error;
+ goto error;
+ }
+ RTE_LOG(INFO, EAL, "%s mapped\n", devname);
}
/* try mapping somewhere close to the end of hugepages */
@@ -135,6 +135,8 @@ struct rte_pci_bus {
/** Device needs PCI BAR mapping (done with either IGB_UIO or VFIO) */
#define RTE_PCI_DRV_NEED_MAPPING 0x0001
+/** Device needs PCI BAR mapping with enabled write combining (wc) */
+#define RTE_PCI_DRV_WC_ACTIVATE 0x0002
/** Device driver supports link state interrupt */
#define RTE_PCI_DRV_INTR_LSC 0x0008
/** Device driver supports device removal interrupt */