$cat /proc/sys/net/ipv4/tcp_dsack 1 $ tcp_dsack – BOOLEAN Allows TCP to send “duplicate” SACKs. This option is required to send duplicate SACKs which was briefly described in the tcp_sack variable explanation. This is described in detail within the RFC 2883. This RFC document explains in detail how to handle situations where a packet is received twice …
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knowledge discovery
Knowledge discovery is a concept of the field of computer science that describes the process of automatically searching large volumes of data for patterns that can be considered knowledge about the data. From Wikipedia, the free encyclopedia.
size of socket reads that will be offloaded to a DMA copy engine
$cat /proc/sys/net/ipv4/tcp_dma_copybreak 4096 $ tcp_dma_copybreak – INTEGER Lower limit, in bytes, of the size of socket reads that will be offloaded to a DMA copy engine, if one is present in the system and CONFIG_NET_DMA is enabled. Default: 4096 grepping through linux kernel source 2.6.32 sysctl_net_ipv4.c: .procname = “tcp_dma_copybreak”,
congestion control algorithm to be used for new connections
ahiliation:~$cat /proc/sys/net/ipv4/tcp_congestion_control cubic ahiliation:~$echo reno > /proc/sys/net/ipv4/tcp_congestion_control bash: /proc/sys/net/ipv4/tcp_congestion_control: Permission denied ahiliation:~$su – Password: debianlabs:~# echo reno > /proc/sys/net/ipv4/tcp_congestion_control debianlabs:~# cat /proc/sys/net/ipv4/tcp_congestion_control reno debianlabs:~# echo dreno > /proc/sys/net/ipv4/tcp_congestion_control -su: echo: write error: No such file or directory Set the congestion control algorithm to be used for new connections. The algorithm “reno” is always available, but …
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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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x87 set of registers
The x87 family does not use a directly addressable register set such as the main registers of the x86 processors; instead the x87 registers form a 8-level deep stack structure ranging from st0 to st7, where st0 is the top. x87 is a floating point-related subset (originally an extension) of the x86 architecture instruction set. …
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 …