从我的家庭服务器（运行 Ubuntu 12.04 Server）到我的 LAN 上的任何其他 PC（全部运行 Windows 7）的文件传输非常慢，但另一个方向（上传到服务器）的文件传输很快。
我在 Samba 和 SFTP 传输中都观察到了这一点，因此决定使用 iperf 进行验证，并得到了相同的结果。服务器上的输出如下所示：
iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
[ 4] local 192.168.1.95 port 5001 connected with 192.168.1.82 port 1309
[ ID] Interval Transfer Bandwidth
[ 4] 0.0-10.0 sec 416 MBytes 349 Mbits/sec
------------------------------------------------------------
Client connecting to 192.168.1.82, TCP port 5001
TCP window size: 46.1 KByte (default)
------------------------------------------------------------
[ 4] local 192.168.1.95 port 59704 connected with 192.168.1.82 port 5001
[ 4] 0.0-12.2 sec 1.50 MBytes 1.03 Mbits/sec
客户端（我的 Win 7 PC）在相同运行中产生了以下输出：
iperf.exe -c 192.168.1.95 -r
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 64.0 KByte (default)
------------------------------------------------------------
------------------------------------------------------------
Client connecting to 192.168.1.95, TCP port 5001
TCP window size: 64.0 KByte (default)
------------------------------------------------------------
[ 4] local 192.168.1.82 port 1309 connected with 192.168.1.95 port 5001
[ ID] Interval Transfer Bandwidth
[ 4] 0.0-10.0 sec 416 MBytes 349 Mbits/sec
[ 4] local 192.168.1.82 port 5001 connected with 192.168.1.95 port 59704
[ 4] 0.0-12.2 sec 1.50 MBytes 1.03 Mbits/sec
其他客户端也观察到了类似的结果。所有计算机都连接到同一个千兆有线交换机。交换它们之间的端口和电缆也会产生相同的结果。
运行服务器上设置的 ramdisk 之间的传输也不会改变传输速度；我不相信硬盘是造成问题的原因。
我尽力在 Google 上搜索类似的问题，但尚未找到任何相关解决方案。有人有什么想法吗？
以下是一些相关调试命令的转储，以防它们对比我更有知识的人有用。
服务器上以太网卡的 ethtool 输出：
ethtool eth0
Settings for eth0:
Supported ports: [ TP MII ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Half 1000baseT/Full
Supported pause frame use: No
Supports auto-negotiation: Yes
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Half 1000baseT/Full
Advertised pause frame use: Symmetric Receive-only
Advertised auto-negotiation: Yes
Link partner advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Half 1000baseT/Full
Link partner advertised pause frame use: Symmetric Receive-only
Link partner advertised auto-negotiation: Yes
Speed: 1000Mb/s
Duplex: Full
Port: MII
PHYAD: 0
Transceiver: internal
Auto-negotiation: on
Supports Wake-on: pumbg
Wake-on: g
Current message level: 0x00000033 (51)
drv probe ifdown ifup
Link detected: yes
Mii-tool 输出：
sudo mii-tool
eth0: negotiated 1000baseT-HD flow-control, link ok
lspci 返回的硬件列表：
sudo lspci
00:00.0 Host bridge: VIA Technologies, Inc. CN700/VN800/P4M800CE/Pro Host Bridge
00:00.1 Host bridge: VIA Technologies, Inc. CN700/VN800/P4M800CE/Pro Host Bridge
00:00.2 Host bridge: VIA Technologies, Inc. CN700/VN800/P4M800CE/Pro Host Bridge
00:00.3 Host bridge: VIA Technologies, Inc. PT890 Host Bridge
00:00.4 Host bridge: VIA Technologies, Inc. CN700/VN800/P4M800CE/Pro Host Bridge
00:00.7 Host bridge: VIA Technologies, Inc. CN700/VN800/P4M800CE/Pro Host Bridge
00:01.0 PCI bridge: VIA Technologies, Inc. VT8237/VX700 PCI Bridge
00:08.0 Network controller: Broadcom Corporation BCM4306 802.11b/g Wireless LAN Controller (rev 03)
00:09.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8110SC/8169SC Gigabit Ethernet (rev 10)
00:0b.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8110SC/8169SC Gigabit Ethernet (rev 10)
00:0f.0 IDE interface: VIA Technologies, Inc. VIA VT6420 SATA RAID Controller (rev 80)
00:0f.1 IDE interface: VIA Technologies, Inc. VT82C586A/B/VT82C686/A/B/VT823x/A/C PIPC Bus Master IDE (rev 06)
00:10.0 USB controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 Controller (rev 81)
00:10.1 USB controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 Controller (rev 81)
00:10.2 USB controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 Controller (rev 81)
00:10.3 USB controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 Controller (rev 81)
00:10.4 USB controller: VIA Technologies, Inc. USB 2.0 (rev 86)
00:11.0 ISA bridge: VIA Technologies, Inc. VT8237 ISA bridge [KT600/K8T800/K8T890 South]
00:11.5 Multimedia audio controller: VIA Technologies, Inc. VT8233/A/8235/8237 AC97 Audio Controller (rev 60)
01:00.0 VGA compatible controller: VIA Technologies, Inc. CN700/P4M800 Pro/P4M800 CE/VN800 Graphics [S3 UniChrome Pro] (rev 01)
lsmod 返回的已加载驱动程序列表：
sudo lsmod
Module Size Used by
usb_storage 39646 0
vesafb 13516 1
ppdev 12849 0
arc4 12473 2
snd_via82xx 24718 0
gameport 15060 1 snd_via82xx
snd_ac97_codec 110213 1 snd_via82xx
b43 342801 0
ac97_bus 12642 1 snd_ac97_codec
snd_pcm 80916 2 snd_via82xx,snd_ac97_codec
snd_timer 28931 1 snd_pcm
snd_page_alloc 14108 2 snd_via82xx,snd_pcm
snd_mpu401_uart 13865 1 snd_via82xx
snd_rawmidi 25424 1 snd_mpu401_uart
snd_seq_device 14172 1 snd_rawmidi
snd 62218 7 snd_via82xx,snd_ac97_codec,snd_pcm,snd_timer,snd_mpu401_uart,snd_rawmidi,snd_seq_device
mac80211 436493 1 b43
soundcore 14635 1 snd
serio_raw 13027 0
i2c_viapro 12969 0
cfg80211 178877 2 b43,mac80211
bcma 25651 1 b43
parport_pc 32114 1
shpchp 32265 0
mac_hid 13077 0
via_cputemp 13031 0
hwmon_vid 12723 1 via_cputemp
lp 17455 0
parport 40930 3 ppdev,parport_pc,lp
pata_via 13428 0
ssb 50691 1 b43
r8169 56396 0
sata_via 13495 2
千兆卡的驱动信息：
sudo modinfo r8169
filename: /lib/modules/3.2.0-51-generic-pae/kernel/drivers/net/ethernet/realtek/r8169.ko
version: 6.017.00-NAPI
license: GPL
description: RealTek RTL-8169 Gigabit Ethernet driver
author: Realtek and the Linux r8169 crew <[email protected]>
srcversion: 231149B837AF2B63F7C0271
alias: pci:v00001186d00004300sv00001186sd00004C00bc*sc*i*
alias: pci:v000010ECd00008169sv*sd*bc*sc*i*
alias: pci:v000010ECd00008167sv*sd*bc*sc*i*
depends:
vermagic: 3.2.0-51-generic-pae SMP mod_unload modversions 686
parm: speed:force phy operation. Deprecated by ethtool (8). (array of int)
parm: duplex:force phy operation. Deprecated by ethtool (8). (array of int)
parm: autoneg:force phy operation. Deprecated by ethtool (8). (array of int)
parm: rx_copybreak:Copy breakpoint for copy-only-tiny-frames (int)
parm: use_dac:Enable PCI DAC. Unsafe on 32 bit PCI slot. (int)
parm: debug:Debug verbosity level (0=none, ..., 16=all) (int)
...并使用 uname -a 进行测量：
uname -a
Linux hotblack 3.2.0-51-generic-pae #77-Ubuntu SMP Wed Jul 24 20:40:32 UTC 2013 i686 i686 i386 GNU/Linux
如果有人认为任何其他调试输出会有帮助，请随时询问。
更新
由于想要更好的方法来测试不同的驱动程序，我还尝试在启动时退回到旧内核，将 r8169 返回到 v2.3LK-NAPI，但问题仍然存在。
然而，我发现了一个有趣的现象。如果我使用 ethtool 将网卡强制恢复到 100Mb...
sudo ethtool -s eth0 speed 100 autoneg on duplex full
sudo ethtool eth0
Settings for eth0:
Supported ports: [ TP ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Supported pause frame use: No
Supports auto-negotiation: Yes
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
Advertised pause frame use: Symmetric Receive-only
Advertised auto-negotiation: Yes
Speed: 100Mb/s
Duplex: Full
Port: Twisted Pair
PHYAD: 0
Transceiver: internal
Auto-negotiation: on
MDI-X: Unknown
Supports Wake-on: pumbg
Wake-on: g
Current message level: 0x00000033 (51)
drv probe ifdown ifup
Link detected: yes
...然后 iperf 显示连接在两个方向上都运行正常：
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
[ 4] local 192.168.1.95 port 5001 connected with 192.168.1.82 port 2437
[ ID] Interval Transfer Bandwidth
[ 4] 0.0-10.0 sec 105 MBytes 87.7 Mbits/sec
------------------------------------------------------------
Client connecting to 192.168.1.82, TCP port 5001
TCP window size: 83.9 KByte (default)
------------------------------------------------------------
[ 4] local 192.168.1.95 port 40844 connected with 192.168.1.82 port 5001
[ 4] 0.0-10.0 sec 113 MBytes 94.4 Mbits/sec
我不确定从中可以得出什么结论，但这至少进一步证明上传速度没有受到硬件的限制……
答案1
我以前见过这种情况，是由双工不匹配引起的。千兆以太网的规范要求双方都使用自动协商，因此请确保服务器和客户端上的 NIC 设置为自动协商，交换机端口也设置为自动协商。明确将其设置为 1000/Full 不会实现此目的。
我从你的一个输出中看到：
协商 1000baseT-HD 流量控制，链接正常
这看起来像是半双工。当双方都没有设置为自动时，两个连接之间的自动协商阶段会正确检测到 1000mbps 速度，但无法发现双工模式，因此它使用默认的半双工。因此，您有 2 个设备尝试通信，一个是全双工，另一个是半双工。最终结果是来自一侧的流量导致大量数据包错误，迫使数据包重新发送并降低该方向的传输速率。
我通过这种方式解决了服务器和 NAS 盒之间的问题，一张卡已设置为自动，另一张卡明确设置为 1000/Full。
答案2
我的机器也遇到过类似的问题。下载到机器的速度是 2MB/s，而从机器上传的速度只有 55kB/s。我尝试了上述所有技巧，检查了交换机、电缆等，但都不起作用。最后，解决我问题的方法是将以太网卡从网络管理器中取出（在 /etc/NetworkManager/NetworkManager.conf 中设置 managed=false），然后在 /etc/network/interfaces 中手动设置设备
auto eth0
iface eth0 inet dhcp
现在我在两个方向上都可以获得 1MB/s。