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Diffstat (limited to 'Documentation/topics/dpdk/memory.rst')
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diff --git a/Documentation/topics/dpdk/memory.rst b/Documentation/topics/dpdk/memory.rst index 8b7758e6e..9714d79d4 100644 --- a/Documentation/topics/dpdk/memory.rst +++ b/Documentation/topics/dpdk/memory.rst @@ -213,3 +213,47 @@ Example 3: (2 rxq, 2 PMD, 9000 MTU) Number of mbufs = (2 * 2048) + (3 * 2048) + (1 * 32) + (16384) = 26656 Mbuf size = 10176 Bytes Memory required = 26656 * 10176 = 271 MB + +Shared Mempool Configuration +---------------------------- + +In order to increase sharing of mempools, a user can configure the MTUs which +mempools are based on by using ``shared-mempool-config``. + +An MTU configured by the user is adjusted to an mbuf size used for mempool +creation and stored. If a port is subsequently added that has an MTU which can +be accommodated by this mbuf size, it will be used for mempool creation/reuse. + +This can increase sharing by consolidating mempools for ports with different +MTUs which would otherwise use separate mempools. It can also help to remove +the need for mempools being created after a port is added but before it's MTU +is changed to a different value. + +For example, on a 2 NUMA system:: + + $ ovs-vsctl ovs-vsctl --no-wait set Open_vSwitch . \ + other_config:shared-mempool-config=9000,1500:1,6000:1 + + +In this case, OVS stores the mbuf sizes based on the following MTUs. + +* NUMA 0: 9000 +* NUMA 1: 1500, 6000, 9000 + +Ports added will use mempools with the mbuf sizes based on the above MTUs where +possible. If there is more than one suitable, the one closest to the MTU will +be selected. + +Port added on NUMA 0: + +* MTU 1500, use mempool based on 9000 MTU +* MTU 6000, use mempool based on 9000 MTU +* MTU 9000, use mempool based on 9000 MTU +* MTU 9300, use mempool based on 9300 MTU (existing behaviour) + +Port added on NUMA 1: + +* MTU 1500, use mempool based on 1500 MTU +* MTU 6000, use mempool based on 6000 MTU +* MTU 9000, use mempool based on 9000 MTU +* MTU 9300, use mempool based on 9300 MTU (existing behaviour) |