---
- branch: MAIN
  date: Fri Oct 13 19:07:09 UTC 2023
  files:
  - new: '1.187'
    old: '1.186'
    path: src/sys/ddb/db_command.c
    pathrev: src/sys/ddb/db_command.c@1.187
    type: modified
  - new: '1.42'
    old: '1.41'
    path: src/sys/ddb/db_interface.h
    pathrev: src/sys/ddb/db_interface.h@1.42
    type: modified
  - new: '1.78'
    old: '1.77'
    path: src/sys/ddb/db_xxx.c
    pathrev: src/sys/ddb/db_xxx.c@1.78
    type: modified
  - new: '1.165'
    old: '1.164'
    path: src/sys/kern/sys_pipe.c
    pathrev: src/sys/kern/sys_pipe.c@1.165
    type: modified
  - new: '1.40'
    old: '1.39'
    path: src/sys/sys/pipe.h
    pathrev: src/sys/sys/pipe.h@1.40
    type: modified
  - new: '1.119'
    old: '1.118'
    path: src/usr.bin/fstat/fstat.c
    pathrev: src/usr.bin/fstat/fstat.c@1.119
    type: modified
  id: 20231013T190709Z.6aa82decbcfcbd128e8c8f3195eb7111c216d678
  log: |
    Simplify/streamline pipes a little bit:

    - Allocate only one struct pipe not two (no need to be bidirectional here).
    - Then use f_flag (FREAD/FWRITE) to figure out what to do in the fileops.
    - Never wake the other side or acquire long-term (I/O) lock unless needed.
    - Whenever possible, defer wakeups until after locks have been released.
    - Do some things locklessly in pipe_ioctl() and pipe_poll().

    Some notable results:

    - -30% latency on a 486DX2/66 doing 1 byte ping-pong within a single process.
    - 2.5x less lock contention during "make cleandir" of src on a 48 CPU machine.
    - 1.5x bandwith with 1kB messages on the same 48 CPU machine (8kB: same b/w).
  module: src
  subject: 'CVS commit: src'
  unixtime: '1697224029'
  user: ad