tap: safe sndbuf default
With current sndbuf default value, a blocked
target guest can prevent another guest from
transmitting any packets. While current
sndbuf value (1M) is reported to help some
UDP based workloads, the default should
be safe (0).
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/qemu-options.hx b/qemu-options.hx
index 939297a..598a1bd 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1057,7 +1057,7 @@
" use '[down]script=no' to disable script execution\n"
" use 'fd=h' to connect to an already opened TAP interface\n"
" use 'sndbuf=nbytes' to limit the size of the send buffer (the\n"
- " default of 'sndbuf=1048576' can be disabled using 'sndbuf=0')\n"
+ " default is disabled 'sndbuf=0' to enable flow control set 'sndbuf=1048576')\n"
" use vnet_hdr=off to avoid enabling the IFF_VNET_HDR tap flag\n"
" use vnet_hdr=on to make the lack of IFF_VNET_HDR support an error condition\n"
" use vhost=on to enable experimental in kernel accelerator\n"
