From dfd9f52873b9979e3f4a91d87b02c18815c10fff Mon Sep 17 00:00:00 2001 From: Wenjia Zhang Date: Tue, 2 Feb 2021 11:25:04 +0100 Subject: [PATCH] hsci: fix packet loss caused by large MTU MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit For maximum performance the MTU of an HSCI interface was set to the value of the MTU of its HiperSockets interface. However, the MTU of a HiperSockets interface can be very large, and when the data packets are not sent over the HiperSocket but over the corresponding ethernet interface (which usually has a smaller MTU size) then it can happen that the large packets are silently dropped. One example would be communication from an HSCI in one CEC to another HSCI in another CEC via Ethernet. To solve the problem, the MTU setting in this tool is removed, and the default MTU value is used. Thus, the minimum value of the MTUs of the both converged interfaces is used as the MTU of the HSCI interface. Fixes: 0566a492aec7 ("s390-tools: add hsci tool") Signed-off-by: Wenjia Zhang Reviewed-by: Alexandra Winter Signed-off-by: Jan Höppner --- hsci/hsci | 10 ---------- 1 file changed, 10 deletions(-) diff --git a/hsci/hsci b/hsci/hsci index 33dd00d0..c39063f1 100755 --- a/hsci/hsci +++ b/hsci/hsci @@ -253,16 +253,6 @@ function add_hsci { return 1 fi - # use hsdev MTU - if [ -e /sys/class/net/$hsdev/mtu ]; then - hs_mtu="$(cat /sys/class/net/$hsdev/mtu)" - ip link set dev $hsci mtu $hs_mtu >/dev/null 2>&1 - if [ $? -ne 0 ]; then - echo "Error: Failed to set MTU for $hsci " >&2 - clean_up - return 1 - fi - fi ip link set dev $hsci up >/dev/null 2>&1 if [ $? -ne 0 ]; then echo "Error: Failed to set $hsci up" >&2