diff options
author | Len Brown <len.brown@intel.com> | 2008-10-22 23:57:26 -0400 |
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committer | Len Brown <len.brown@intel.com> | 2008-10-23 00:11:07 -0400 |
commit | 057316cc6a5b521b332a1d7ccc871cd60c904c74 (patch) | |
tree | 4333e608da237c73ff69b10878025cca96dcb4c8 /Documentation/networking/multiqueue.txt | |
parent | 3e2dab9a1c2deb03c311eb3f83466009147ed4d3 (diff) | |
parent | 2515ddc6db8eb49a79f0fe5e67ff09ac7c81eab4 (diff) |
Merge branch 'linus' into test
Conflicts:
MAINTAINERS
arch/x86/kernel/acpi/boot.c
arch/x86/kernel/acpi/sleep.c
drivers/acpi/Kconfig
drivers/pnp/Makefile
drivers/pnp/quirks.c
Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'Documentation/networking/multiqueue.txt')
-rw-r--r-- | Documentation/networking/multiqueue.txt | 54 |
1 files changed, 53 insertions, 1 deletions
diff --git a/Documentation/networking/multiqueue.txt b/Documentation/networking/multiqueue.txt index d391ea63114..4caa0e314cc 100644 --- a/Documentation/networking/multiqueue.txt +++ b/Documentation/networking/multiqueue.txt @@ -24,4 +24,56 @@ netif_{start|stop|wake}_subqueue() functions to manage each queue while the device is still operational. netdev->queue_lock is still used when the device comes online or when it's completely shut down (unregister_netdev(), etc.). -Author: Peter P. Waskiewicz Jr. <peter.p.waskiewicz.jr@intel.com> + +Section 2: Qdisc support for multiqueue devices + +----------------------------------------------- + +Currently two qdiscs are optimized for multiqueue devices. The first is the +default pfifo_fast qdisc. This qdisc supports one qdisc per hardware queue. +A new round-robin qdisc, sch_multiq also supports multiple hardware queues. The +qdisc is responsible for classifying the skb's and then directing the skb's to +bands and queues based on the value in skb->queue_mapping. Use this field in +the base driver to determine which queue to send the skb to. + +sch_multiq has been added for hardware that wishes to avoid head-of-line +blocking. It will cycle though the bands and verify that the hardware queue +associated with the band is not stopped prior to dequeuing a packet. + +On qdisc load, the number of bands is based on the number of queues on the +hardware. Once the association is made, any skb with skb->queue_mapping set, +will be queued to the band associated with the hardware queue. + + +Section 3: Brief howto using MULTIQ for multiqueue devices +--------------------------------------------------------------- + +The userspace command 'tc,' part of the iproute2 package, is used to configure +qdiscs. To add the MULTIQ qdisc to your network device, assuming the device +is called eth0, run the following command: + +# tc qdisc add dev eth0 root handle 1: multiq + +The qdisc will allocate the number of bands to equal the number of queues that +the device reports, and bring the qdisc online. Assuming eth0 has 4 Tx +queues, the band mapping would look like: + +band 0 => queue 0 +band 1 => queue 1 +band 2 => queue 2 +band 3 => queue 3 + +Traffic will begin flowing through each queue based on either the simple_tx_hash +function or based on netdev->select_queue() if you have it defined. + +The behavior of tc filters remains the same. However a new tc action, +skbedit, has been added. Assuming you wanted to route all traffic to a +specific host, for example 192.168.0.3, through a specific queue you could use +this action and establish a filter such as: + +tc filter add dev eth0 parent 1: protocol ip prio 1 u32 \ + match ip dst 192.168.0.3 \ + action skbedit queue_mapping 3 + +Author: Alexander Duyck <alexander.h.duyck@intel.com> +Original Author: Peter P. Waskiewicz Jr. <peter.p.waskiewicz.jr@intel.com> |