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Date: Wed, 9 Dec 2015 11:42:51 +0800
From: Yuanhan Liu <yuanhan.liu@linux.intel.com>
To: "Xie, Huawei" <huawei.xie@intel.com>
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Cc: "dev@dpdk.org" <dev@dpdk.org>, Victor Kaplansky <victork@redhat.com>,
 "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [dpdk-dev] [PATCH 2/4] vhost: introduce vhost_log_write
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On Wed, Dec 09, 2015 at 03:33:16AM +0000, Xie, Huawei wrote:
...
> >> +static inline void __attribute__((always_inline))
> >> +vhost_log_write(struct virtio_net *dev, struct vhost_virtqueue *vq,
> >> +		uint64_t offset, uint64_t len)
> >> +{
> >> +	uint64_t addr = vq->log_guest_addr;
> >> +	uint64_t page;
> >> +
> >> +	if (unlikely(((dev->features & (1ULL << VHOST_F_LOG_ALL)) == 0) ||
> >> +		     !dev->log_base || !len))
> >> +		return;
> > Isn't "likely" more appropriate in above, since the whole
> > expression is expected to be true most of the time?
> Victor:
> So we are not always logging, what is the message that tells the backend
> the migration is started?

When log starts, VHOST_USER_SET_FEATURES request will be sent again,
with VHOST_F_LOG_ALL feature bit set.

	--yliu