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dpif-netdev: Block pmd threads if there are no ports.

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There's no reason for a pmd thread to perform its main loop if there are
no queues in its poll_list.

This commit introduces a seq object on which the pmd thread can be
blocked, if there are no queues.

When the main thread wants to reload a pmd threads it must now change
the seq object (in case it's blocked) and set 'reload' to true.

This is useful to avoid wasting CPU cycles and is also necessary for a
future commit.

Signed-off-by: Daniele Di Proietto <diproiettod@vmware.com>
Acked-by: Ilya Maximets <i.maximets@samsung.com>
This commit is contained in:
Daniele Di Proietto
2016-11-15 15:40:49 -08:00
parent 14e3e12ac3
commit 2788a1b138
1 changed files with 15 additions and 0 deletions
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15
lib/dpif-netdev.c
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@@ -485,6 +485,8 @@ struct dp_netdev_pmd_thread {
unsigned long long last_cycles;
struct latch exit_latch; /* For terminating the pmd thread. */
struct seq *reload_seq;
uint64_t last_reload_seq;
atomic_bool reload; /* Do we need to reload ports? */
pthread_t thread;
unsigned core_id; /* CPU core id of this pmd thread. */
@@ -1209,6 +1211,7 @@ dp_netdev_reload_pmd__(struct dp_netdev_pmd_thread *pmd)
}
ovs_mutex_lock(&pmd->cond_mutex);
seq_change(pmd->reload_seq);
atomic_store_relaxed(&pmd->reload, true);
ovs_mutex_cond_wait(&pmd->cond, &pmd->cond_mutex);
ovs_mutex_unlock(&pmd->cond_mutex);
@@ -3164,6 +3167,14 @@ reload:
netdev_rxq_get_queue_id(poll_list[i].rx));
}
if (!poll_cnt) {
while (seq_read(pmd->reload_seq) == pmd->last_reload_seq) {
seq_wait(pmd->reload_seq, pmd->last_reload_seq);
poll_block();
}
lc = UINT_MAX;
}
for (;;) {
for (i = 0; i < poll_cnt; i++) {
dp_netdev_process_rxq_port(pmd, poll_list[i].port, poll_list[i].rx);
@@ -3239,6 +3250,7 @@ dp_netdev_pmd_reload_done(struct dp_netdev_pmd_thread *pmd)
{
ovs_mutex_lock(&pmd->cond_mutex);
atomic_store_relaxed(&pmd->reload, false);
pmd->last_reload_seq = seq_read(pmd->reload_seq);
xpthread_cond_signal(&pmd->cond);
ovs_mutex_unlock(&pmd->cond_mutex);
}
@@ -3333,6 +3345,8 @@ dp_netdev_configure_pmd(struct dp_netdev_pmd_thread *pmd, struct dp_netdev *dp,
ovs_refcount_init(&pmd->ref_cnt);
latch_init(&pmd->exit_latch);
pmd->reload_seq = seq_create();
pmd->last_reload_seq = seq_read(pmd->reload_seq);
atomic_init(&pmd->reload, false);
xpthread_cond_init(&pmd->cond, NULL);
ovs_mutex_init(&pmd->cond_mutex);
@@ -3372,6 +3386,7 @@ dp_netdev_destroy_pmd(struct dp_netdev_pmd_thread *pmd)
cmap_destroy(&pmd->flow_table);
ovs_mutex_destroy(&pmd->flow_mutex);
latch_destroy(&pmd->exit_latch);
seq_destroy(pmd->reload_seq);
xpthread_cond_destroy(&pmd->cond);
ovs_mutex_destroy(&pmd->cond_mutex);
ovs_mutex_destroy(&pmd->port_mutex);