2018-06-29 11:05 GMT+02:00 Ferruh Yigit <ferruh.yi...@intel.com>:
> On 6/29/2018 9:58 AM, Rafał Kozik wrote:
>> 2018-06-28 16:50 GMT+02:00 Ferruh Yigit <ferruh.yi...@intel.com>:
>>> On 6/28/2018 2:15 PM, Rafal Kozik wrote:
>>>> 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 <r...@semihalf.com>
>>>> Acked-by: Bruce Richardson <bruce.richard...@intel.com>
>>>> ---
>>>> drivers/bus/pci/linux/pci_uio.c | 41
>>>> +++++++++++++++++++++++++++++------------
>>>> drivers/bus/pci/rte_bus_pci.h | 2 ++
>>>> 2 files changed, 31 insertions(+), 12 deletions(-)
>>>>
>>>> diff --git a/drivers/bus/pci/linux/pci_uio.c
>>>> b/drivers/bus/pci/linux/pci_uio.c
>>>> index d423e4b..e3947c2 100644
>>>> --- a/drivers/bus/pci/linux/pci_uio.c
>>>> +++ b/drivers/bus/pci/linux/pci_uio.c
>>>> @@ -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 +306,31 @@ 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);
>>>
>>> What do you think adding an error log here? If opening resource$_wc fails
>>> and
>>> fallback to resource# file, there won't be any way for user to know about
>>> it.
>>>
>>
>> This error will be misleading for two reasons:
>> * even if open return success, it could silently fall-back to non
>> prefetchable mode,
>> * NICs could have multiple BARs, but not all support WC. I such case
>> fails will be desirable.
>
> OK, perhaps not error log to prevent mislead, but what do you think "info"
> level
> log, to notify the user that write combined version in not used.
>
In new revision of patch set I add logging of device name.
For every resources it provides information if mapped with or without WC.
It looks like:
EAL: /sys/bus/pci/devices/0000:00:06.0/resource0 mapped
EAL: /sys/bus/pci/devices/0000:00:06.0/resource2_wc mapped
EAL: /sys/bus/pci/devices/0000:00:06.0/resource4 mapped
>>
>>>> + }
>>>> +
>>>> + 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;
>>>> + }
>>>> }
>>>>
>>>> /* try mapping somewhere close to the end of hugepages */
>>>> diff --git a/drivers/bus/pci/rte_bus_pci.h b/drivers/bus/pci/rte_bus_pci.h
>>>> index 458e6d0..828acc5 100644
>>>> --- a/drivers/bus/pci/rte_bus_pci.h
>>>> +++ b/drivers/bus/pci/rte_bus_pci.h
>>>> @@ -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 */
>>>>
>>>
>
