Author Archives: jeffrin

The initial value of search_low to be used by the packetization layer

$cat /proc/sys/net/ipv4/tcp_base_mss 512 $ tcp_base_mss – INTEGER The initial value of search_low to be used by the packetization layer Path MTU discovery (MTU probing). If MTU probing is enabled, this is the initial MSS used by the connection. grepping through linux kernel source 2.6.32 sysctl_net_ipv4.c: .procname = “tcp_base_mss”, sysctl_net_ipv4.c: .data = &sysctl_tcp_base_mss, tcp_output.c:int sysctl_tcp_base_mss __read_mostly …

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scale factor for portion of window reserved for buffering overhead

$cat /proc/sys/net/ipv4/tcp_app_win 31 $ Scale factor for portion of window reserved for buffering overhead. Reserve max(window / 2 ^ tcp_app_win, mss) of window for application buffer. Value 0 is special, it means that nothing is reserved. The default value is 31. [ wireshark ] Frame 1 (1496 bytes on wire, 1496 bytes captured) Ethernet II, …

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scaling factor for calculating application portion of window

$cat /proc/sys/net/ipv4/tcp_adv_win_scale 2 $ Scaling factor for calculating application portion of window. Count buffering overhead as bytes / 2 ^ tcp_adv_win_scale (if tcp_adv_win_scale > 0) or bytes – bytes / 2 ^ (-tcp_adv_win_scale), if it is <= 0. The default value is 2. Copyright © 2002 by Oskar Andreasson Under GNU FDL. linux kernel source …

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names of targets and files being debugged

From gdb. info files — Names of targets and files being debugged Local exec file: `/usr/bin/xine’, file type elf64-x86-64. Entry point: 0x409e30 0x0000000000400200 – 0x000000000040021c is .interp 0x000000000040021c – 0x000000000040023c is .note.ABI-tag 0x000000000040023c – 0x0000000000400260 is .note.gnu.build-id 0x0000000000400260 – 0x0000000000400dac is .hash 0x0000000000400db0 – 0x0000000000400e6c is .gnu.hash 0x0000000000400e70 – 0x0000000000403960 is .dynsym 0x0000000000403960 – 0x00000000004053f8 …

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tcp tuning tcp_abort_on_overflow

$cat /proc/sys/net/ipv4/tcp_abort_on_overflow 0 $ The tcp_abort_on_overflow variable tells the kernel to reset new connections if the system is currently overflowed with new connection attempts that the daemon(s) can not handle. What this means, is that if the system is overflowed with 1000 large requests in a burst, connections may be reset since we can not …

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windows registry

regedit is the command to invoke registry editor. it can be used for windows TCP tuning. The Windows Registry is a hierarchical database that stores configuration settings and options on Microsoft Windows operating systems. It contains settings for low-level operating system components as well as the applications running on the platform: the kernel, device drivers, …

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tcp tuning tcp_reordering

[:–:]cat /proc/sys/net/ipv4/tcp_reordering 3 [:–:] The tcp_reordering variable tells the kernel how much a TCP packet may be reordered in a stream without assuming that the packet was lost somewhere on the way. If the packet is assumed lost, the TCP stack will automatically go back into a slow start since it believes packets may have …

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tcp tuning tcp_abc

echo 1 > /proc/sys/net/ipv4/tcp_abc From RFC 3465. A Modified Algorithm for Increasing the Congestion Window As originally outlined in [Jac88] and specified in [RFC2581], TCP uses two algorithms for increasing the congestion window. During steady-state, TCP uses the Congestion Avoidance algorithm to linearly increase the value of cwnd. At the beginning of a transfer, after …

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