[dpdk-stable] patch 'vhost: fix long stall of negotiation' has been queued to stable release 16.11.1

[Yuanhan Liu]

Hi,

FYI, your patch has been queued to stable release 16.11.1

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable
yet. It will be pushed if I get no objections before 02/18/17.
So please shout if anyone has objections.

Thanks.

	--yliu

---
>From a65fa5bd927ce2a496b04241bca29c94c3fbfe7e Mon Sep 17 00:00:00 2001
From: Yuanhan Liu <yuanhan.liu at linux.intel.com>
Date: Sun, 22 Jan 2017 16:46:59 +0800
Subject: [PATCH] vhost: fix long stall of negotiation

[ upstream commit b8b992e93f387b0d0dda00b9feb6adb05ffe081c ]

Setting up the mapping from GPA (guest physical address) to HPA (guest
physical address) could be very time consuming when the guest memory is
backened with small pages (4K). The bigger the guest memory, the longer
it takes. This could lead a very long vhost-user negotiation.

Since the mapping is only needed in zero copy mode so far, we could
avoid such time consuming settup when zero copy is turned off (which is
the default case).

It's actually a workaround, a right fix might be to start a new thread,
and hide the big latency there.

Fixes: e246896178e6 ("vhost: get guest/host physical address mappings")

Signed-off-by: Yuanhan Liu <yuanhan.liu at linux.intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin at redhat.com>
---
 lib/librte_vhost/vhost_user.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index 50cb6d1..0cb1c67 100644
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -567,7 +567,8 @@ vhost_user_set_mem_table(struct virtio_net *dev, struct VhostUserMsg *pmsg)
 		reg->host_user_addr = (uint64_t)(uintptr_t)mmap_addr +
 				      mmap_offset;
 
-		add_guest_pages(dev, reg, alignment);
+		if (dev->dequeue_zero_copy)
+			add_guest_pages(dev, reg, alignment);
 
 		RTE_LOG(INFO, VHOST_CONFIG,
 			"guest memory region %u, size: 0x%" PRIx64 "\n"
-- 
1.9.0