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Drivers: hv: vmbus: distribute subchannels among all vcpus

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Primary channels are distributed evenly across all vcpus we have. When the host
asks us to create subchannels it usually makes us num_cpus-1 offers and we are
supposed to distribute the work evenly among the channel itself and all its
subchannels. Make sure they are all assigned to different vcpus.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Vitaly Kuznetsov 2015-05-06 17:47:46 -07:00 committed by Greg Kroah-Hartman
parent f38e7dd723
commit ce59fec836
1 changed files with 28 additions and 1 deletions
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27
drivers/hv/channel_mgmt.c
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@ -387,6 +387,8 @@ static void init_vp_index(struct vmbus_channel *channel, const uuid_le *type_gui
int i;
bool perf_chn = false;
u32 max_cpus = num_online_cpus();
struct vmbus_channel *primary = channel->primary_channel, *prev;
unsigned long flags;
for (i = IDE; i < MAX_PERF_CHN; i++) {
if (!memcmp(type_guid->b, hp_devs[i].guid,
@ -407,7 +409,32 @@ static void init_vp_index(struct vmbus_channel *channel, const uuid_le *type_gui
channel->target_vp = 0;
return;
}
/*
* Primary channels are distributed evenly across all vcpus we have.
* When the host asks us to create subchannels it usually makes us
* num_cpus-1 offers and we are supposed to distribute the work evenly
* among the channel itself and all its subchannels. Make sure they are
* all assigned to different vcpus.
*/
if (!primary)
cur_cpu = (++next_vp % max_cpus);
else {
/*
* Let's assign the first subchannel of a channel to the
* primary->target_cpu+1 and all the subsequent channels to
* the prev->target_cpu+1.
*/
spin_lock_irqsave(&primary->lock, flags);
if (primary->num_sc == 1)
cur_cpu = (primary->target_cpu + 1) % max_cpus;
else {
prev = list_prev_entry(channel, sc_list);
cur_cpu = (prev->target_cpu + 1) % max_cpus;
}
spin_unlock_irqrestore(&primary->lock, flags);
}
channel->target_cpu = cur_cpu;
channel->target_vp = hv_context.vp_index[cur_cpu];
}