From b8b992e93f387b0d0dda00b9feb6adb05ffe081c Mon Sep 17 00:00:00 2001
From: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Date: Sun, 22 Jan 2017 16:46:59 +0800
Subject: [PATCH] vhost: fix long stall of negotiation
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")
Cc: stable@dpdk.org
Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@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 7343a00a1e..ab7f3fcf46 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"