On Mon, 2008-05-12 at 14:00 -0500, Shirish Pargaonkar wrote: > Hello, > > kernel_sendmsg fails with error EAGAIN, yet I no matter how long I try, > I still get the same error and do not see the send buffer size of a socket > changing (increasing) > > The initial buffer sizes are 16384 for send side and 87380 for the receive > side but I see receive side buffer tuning but do not see the same with > send side. > > If tcp does not see a need to increase the send buffer size, wonder why I > get EAGAIN error on this non-blocking socket for kernel_sendmsg! I think the send buffer auto-tuning doesn't happen here because there is already congestion window worth of packets sent that are not yet acknowledged. See tcp_should_expand_sndbuf(). Also, the comments for tcp_new_space() says that sndbuf expansion does not work well with largesends. What is the size of your sends? Adding netdev to the CC list. Thanks Sridhar > > I do subscribe to this mailing list so, please send your responses to this > mail address. > > Regards, > > Shirish > > -------------------------------------------------------------------------------------------------- > uname -r > 2.6.18-91.el5 > > sysctl -a > > net.ipv4.tcp_rmem = 4096 87380 4194304 > net.ipv4.tcp_wmem = 4096 16384 4194304 > net.ipv4.tcp_mem = 98304 131072 196608 > > net.core.rmem_default = 126976 > net.core.wmem_default = 126976 > net.core.rmem_max = 131071 > net.core.wmem_max = 131071 > > net.ipv4.tcp_window_scaling = 1 > net.ipv4.tcp_timestamps = 1 > net.ipv4.tcp_moderate_rcvbuf = 1 > > > cat /proc/sys/net/ipv4/tcp_moderate_rcvbuf > 1 > > > CIFS VFS: sndbuf 16384 rcvbuf 87380 > > CIFS VFS: sends on sock 0000000009903100, sendbuf 34776, rcvbuf 190080 > stuck for 32 seconds, > error: -11 > CIFS VFS: sends on sock 0000000009903a00, sndbuf 34776, rcvbuf 138240 > stuck for 32 seconds, > error: -11 > > > CIFS VFS: sends on sock 0000000009903100, sndbuf 34776, rcvbuf 126720 > stuck for 64 seconds, > error: -11 > > CIFS VFS: sends on sock 0000000009903100, sndbuf 34776, rcvbuf 222720 > stuck for 256 seconds, > error: -11 > > I see the socket receive buffer size fluctuating (tcp_moderate_rcvbuf > is 1) but not > the socket send buffer size. > The send buffer size remains fixed, the auto-tuning for send side is > enabled by default,so I do not see it happening here no matter how > long the c ode tries to > kernel_sendmsg after receiving EAGAIN return code. > -- > To unsubscribe from this list: send the line "unsubscribe linux-net" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-net" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
