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netdev-dpdk: Fix Tx queue false sharing.

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'tx_q' array is allocated for each DPDK netdev.  'struct dpdk_tx_queue'
is 8 bytes long, so 8 tx queues are sharing the same cache line in
case of 64B cacheline size.  This causes 'false sharing' issue in
mutliqueue case because taking the spinlock implies write to memory
i.e. cache invalidation.

Signed-off-by: Ilya Maximets <i.maximets@ovn.org>
Acked-by: Eelco Chaudron <echaudro@redhat.com>
This commit is contained in:
Ilya Maximets
2019-08-26 17:54:04 +03:00
parent d5ad58044a
commit 15ba075d39
1 changed files with 10 additions and 7 deletions
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17
lib/netdev-dpdk.c
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@@ -298,14 +298,17 @@ struct dpdk_mp {
};
/* There should be one 'struct dpdk_tx_queue' created for
* each cpu core. */
* each netdev tx queue. */
struct dpdk_tx_queue {
rte_spinlock_t tx_lock; /* Protects the members and the NIC queue
* from concurrent access. It is used only
* if the queue is shared among different
* pmd threads (see 'concurrent_txq'). */
int map; /* Mapping of configured vhost-user queues
* to enabled by guest. */
/* Padding to make dpdk_tx_queue exactly one cache line long. */
PADDED_MEMBERS(CACHE_LINE_SIZE,
/* Protects the members and the NIC queue from concurrent access.
* It is used only if the queue is shared among different pmd threads
* (see 'concurrent_txq'). */
rte_spinlock_t tx_lock;
/* Mapping of configured vhost-user queue to enabled by guest. */
int map;
);
};
/* dpdk has no way to remove dpdk ring ethernet devices