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hyperv/vmbus: Use atomic swap and flsl to process event flags

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Greatly reduce the locked instructions and reduce number of inner loops.

MFC after:	1 week
Sponsored by:	Microsoft OSTC
Differential Revision:	https://reviews.freebsd.org/D6404
This commit is contained in:
Sepherosa Ziehau 2016-05-18 03:28:51 +00:00
parent 5002e19502
commit 632da4eb89
1 changed files with 17 additions and 17 deletions
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34
sys/dev/hyperv/vmbus/hv_connection.c
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@ -332,32 +332,32 @@ hv_vmbus_on_events(int cpu)
*/
for (f = 0; f < flag_cnt; f++) {
uint32_t rel_id_base;
unsigned long flags;
int bit;
if (intr_flags[f] == 0)
continue;
flags = atomic_swap_long(&intr_flags[f], 0);
rel_id_base = f << HV_CHANNEL_ULONG_SHIFT;
for (bit = 0; bit < HV_CHANNEL_ULONG_LEN; bit++) {
if (atomic_testandclear_long(&intr_flags[f], bit)) {
struct hv_vmbus_channel *channel;
uint32_t rel_id;
rel_id = rel_id_base + bit;
channel =
hv_vmbus_g_connection.channels[rel_id];
while ((bit = ffsl(flags)) != 0) {
struct hv_vmbus_channel *channel;
uint32_t rel_id;
/* if channel is closed or closing */
if (channel == NULL || channel->rxq == NULL)
continue;
--bit; /* NOTE: ffsl is 1-based */
flags &= ~(1UL << bit);
if (channel->batched_reading) {
hv_ring_buffer_read_begin(
&channel->inbound);
}
taskqueue_enqueue(channel->rxq,
&channel->channel_task);
}
rel_id = rel_id_base + bit;
channel = hv_vmbus_g_connection.channels[rel_id];
/* if channel is closed or closing */
if (channel == NULL || channel->rxq == NULL)
continue;
if (channel->batched_reading)
hv_ring_buffer_read_begin(&channel->inbound);
taskqueue_enqueue(channel->rxq, &channel->channel_task);
}
}
}