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When testing with a background iperf pushing 1Gbit/sec traffic and running both ifconfig and netstat to collect statistics, some deadlocks occurred. Ifconfig and netstat will call nv_get_stats64 to get software xmit/recv statistics. In the commitf5d827aece("forcedeth: implement ndo_get_stats64() API"), the normal tx/rx variables is to collect tx/rx statistics. The fix is to replace normal tx/rx variables with per cpu 64-bit variable to collect xmit/recv statistics. The per cpu variable will avoid deadlocks and provide fast efficient statistics updates. In nv_probe, the per cpu variable is initialized. In nv_remove, this per cpu variable is freed. In xmit/recv process, this per cpu variable will be updated. In nv_get_stats64, this per cpu variable on each cpu is added up. Then the driver can get xmit/recv packets statistics. A test runs for several days with this commit, the deadlocks disappear and the performance is better. Tested: - iperf SMP x86_64 -> Client connecting to 1.1.1.108, TCP port 5001 TCP window size: 85.0 KByte (default) ------------------------------------------------------------ [ 3] local 1.1.1.105 port 38888 connected with 1.1.1.108 port 5001 [ ID] Interval Transfer Bandwidth [ 3] 0.0-10.0 sec 1.10 GBytes 943 Mbits/sec ifconfig results: enp0s9 Link encap:Ethernet HWaddr 00:21:28:6f:de:0f inet addr:1.1.1.105 Bcast:0.0.0.0 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:5774764531 errors:0 dropped:0 overruns:0 frame:0 TX packets:633534193 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:7646159340904 (7.6 TB) TX bytes:11425340407722 (11.4 TB) netstat results: Kernel Interface table Iface MTU Met RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg ... enp0s9 1500 0 5774764531 0 0 0 633534193 0 0 0 BMRU ... Fixes:f5d827aece("forcedeth: implement ndo_get_stats64() API") CC: Joe Jin <joe.jin@oracle.com> CC: JUNXIAO_BI <junxiao.bi@oracle.com> Reported-and-tested-by: Nan san <nan.1986san@gmail.com> Signed-off-by: Zhu Yanjun <yanjun.zhu@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.