x86 Floating Point was and still is a source of problems. First of all the FPU (floating point coprocessor, x87) has 8 registers. Via gdb and info all-register you can display the floating point register. These registers are all 80 bit wide. And here the problems start: standardized are floating point math with 32 or 64 bit (float or double). If you compile the next construct with -m32 on a 32bit and a 64bit arch the results will differ:...
net-ping host --no=dns,bind --proto=TCP,rfc:492 eth0@ipv4::http://1.0.0.127.IN -ADDR.ARPA --stats -v ;-) from https://twitter.com/gitHater
Michael published the agenda for TCPM Vancouver Meeting and there are lot of items on the list this time. The following list is sorted by personal interest: Proportional Rate Reduction for TCP TCP Fast Open Increasing TCP’s Initial Window Impact of IW10 on Interactive Real-Time Communication Additional negotiation in the TCP Timestamp Option field during the TCP handshake TCP and SCTP RTO Restart More Accurate ECN Feedback in TCP TCP Loss Probe (TLP): An Algorithm for Fast Recovery of Tail Losses Evaluating TCP Laminar Highly Efficient Selective Acknowledgement (SACK) for TCP Shared Use of Experimental TCP Options A TCP Authentication Option NAT Extension RFC 1323bis HOST_ID TCP Options: Implementation and Preliminary Test Results Shared Memory Communications over RDMA Processing of IP Security/Compartment and Precedence Information by TCP Processing of TCP segments with Mirrored End-points I am especially interested in Ilpo’s Interactive Real-Time Communication IW10 talk....
Just a few bugfixes goes in since -rc7 so here we go: Linux 3.5 released. Changeset of upcoming 3.6 should be smaller because of vacation period.
GCC as enabled with -freorder-blocks and a optimization level larger 1 will reorder instructions at a block level. This optimization is mainly to compress correlated code to provide a optimized cache aware memory layout. Because of some Linux kernel hacking I forced to get the details when and where GCC’s optimizations kicks in. The most effective way for userland programs without branch-taken-knowledge is through profile guided optimization nowadays. But this is not possible in every setup (lack of realistic input data, …)....
Today I buyed a new printer: Epson WP 4535. The printer can scan up to 600 DPI to a USB device (as JPEG or PDF). A nice feature because I dont want to install sane or any other scaner software. Printing works out of the box via CUPS. No additional driver installation required. My room mate tried to test the printer with Windows which failed. Under Windows you must download the actual driver from Epson Homepage....
Vancouver is near so there was a lot of I-D submission progress. I-D cutoff is over so ID submission settles. Subsequent a list of some interesting I-D’s (this list is sorted): A Roadmap for Transmission Control Protocol (TCP) Specification Documents An IPv4 Flowlabel Option Operational Issues with Tunnel Maximum Transmission Unit (MTU) Accurate ECN Feedback Option in TCP Implications of running Internet over ports 80 and 443 OSPFv3 Auto-Configuration Cache DNS Server Selection on the Dual-stack Home Network An Acceptable Use Policy for New ICMP Types and Codes How to Write an RTP Payload Format Definitions of Managed Objects for Packet Sampling IPv6 Guidance for Internet Content and Application Service Providers Formally Deprecating some IPv4 Options Client Identifier Option in DHCP Server Replies TCP Extensions for High Performance IPv6 Path MTU Updates Host Identity Protocol Architecture Domain Names in Application-Layer Protocols From TCP perspective not that much....
Cscope is a crucial part in my development tool zoo. Not for small projects but for larger projects like Linux Kernel development I use cscope really often. But as usually: I only use a small subset of all cscope features. This normally boils down to Ctrl-] to jump to the declaration of the function and later Ctrl-t to jump back. With Cscope the acts like gD (goto declaration) with don’t stop at file boundaries....
The development of captcp flatten out: no more features where implemented in the last months. Today I merges a branch from Gábor Molnár to print TCP stream throughputs separately. New option is can be enables via -x. Many thanks Gábor! This time I used the github merge feature the first time. I rarely use github features. For me it was (and still is) a public git hoster. But Github features like included issue tracking and the whole collaboration thing is great!...
This blog used two third party extensions: Google Analytics Disqus Both set cookies and have a user coverage which is horrible. Nowadays Google Analytics together with Google Search, Android activity and Google Ads have a database of … in the end they know too much about you. I decided today that web analysis data is not crucial for me compared to the privacy of my readers. So I removed all third party content from my blog....