b8d60729de
NOTE: HEADS UP read the note below if your kernel config is not including GENERIC!! This patch does a bit of cleanup on TCP congestion control modules. There were some rather interesting surprises that one could get i.e. where you use a socket option to change from one CC (say cc_cubic) to another CC (say cc_vegas) and you could in theory get a memory failure and end up on cc_newreno. This is not what one would expect. The new code fixes this by requiring a cc_data_sz() function so we can malloc with M_WAITOK and pass in to the init function preallocated memory. The CC init is expected in this case *not* to fail but if it does and a module does break the "no fail with memory given" contract we do fall back to the CC that was in place at the time. This also fixes up a set of common newreno utilities that can be shared amongst other CC modules instead of the other CC modules reaching into newreno and executing what they think is a "common and understood" function. Lets put these functions in cc.c and that way we have a common place that is easily findable by future developers or bug fixers. This also allows newreno to evolve and grow support for its features i.e. ABE and HYSTART++ without having to dance through hoops for other CC modules, instead both newreno and the other modules just call into the common functions if they desire that behavior or roll there own if that makes more sense. Note: This commit changes the kernel configuration!! If you are not using GENERIC in some form you must add a CC module option (one of CC_NEWRENO, CC_VEGAS, CC_CUBIC, CC_CDG, CC_CHD, CC_DCTCP, CC_HTCP, CC_HD). You can have more than one defined as well if you desire. Note that if you create a kernel configuration that does not define a congestion control module and includes INET or INET6 the kernel compile will break. Also you need to define a default, generic adds 'options CC_DEFAULT=\"newreno\" but you can specify any string that represents the name of the CC module (same names that show up in the CC module list under net.inet.tcp.cc). If you fail to add the options CC_DEFAULT in your kernel configuration the kernel build will also break. Reviewed by: Michael Tuexen Sponsored by: Netflix Inc. RELNOTES:YES Differential Revision: https://reviews.freebsd.org/D32693
FreeBSD Source:
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Source Roadmap:
| Directory | Description |
|---|---|
| bin | System/user commands. |
| cddl | Various commands and libraries under the Common Development and Distribution License. |
| contrib | Packages contributed by 3rd parties. |
| crypto | Cryptography stuff (see crypto/README). |
| etc | Template files for /etc. |
| gnu | Various commands and libraries under the GNU Public License. Please see gnu/COPYING and gnu/COPYING.LIB for more information. |
| include | System include files. |
| kerberos5 | Kerberos5 (Heimdal) package. |
| lib | System libraries. |
| libexec | System daemons. |
| release | Release building Makefile & associated tools. |
| rescue | Build system for statically linked /rescue utilities. |
| sbin | System commands. |
| secure | Cryptographic libraries and commands. |
| share | Shared resources. |
| stand | Boot loader sources. |
| sys | Kernel sources. |
sys/arch/conf |
Kernel configuration files. GENERIC is the configuration used in release builds. NOTES contains documentation of all possible entries. |
| tests | Regression tests which can be run by Kyua. See tests/README for additional information. |
| tools | Utilities for regression testing and miscellaneous tasks. |
| usr.bin | User commands. |
| usr.sbin | System administration commands. |
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