diff options
Diffstat (limited to 'scripts/jobserver-exec')
| -rwxr-xr-x | scripts/jobserver-exec | 152 |
1 files changed, 11 insertions, 141 deletions
diff --git a/scripts/jobserver-exec b/scripts/jobserver-exec index 897c0cca9e6e..40a0f0058733 100755 --- a/scripts/jobserver-exec +++ b/scripts/jobserver-exec @@ -1,155 +1,25 @@ #!/usr/bin/env python3 # SPDX-License-Identifier: GPL-2.0+ -# -# pylint: disable=C0103,C0209 -# -# This determines how many parallel tasks "make" is expecting, as it is -# not exposed via an special variables, reserves them all, runs a subprocess -# with PARALLELISM environment variable set, and releases the jobs back again. -# -# https://www.gnu.org/software/make/manual/html_node/POSIX-Jobserver.html#POSIX-Jobserver -""" -Interacts with the POSIX jobserver during the Kernel build time. - -A "normal" jobserver task, like the one initiated by a make subrocess would do: - - - open read/write file descriptors to communicate with the job server; - - ask for one slot by calling: - claim = os.read(reader, 1) - - when the job finshes, call: - os.write(writer, b"+") # os.write(writer, claim) - -Here, the goal is different: This script aims to get the remaining number -of slots available, using all of them to run a command which handle tasks in -parallel. To to that, it has a loop that ends only after there are no -slots left. It then increments the number by one, in order to allow a -call equivalent to make -j$((claim+1)), e.g. having a parent make creating -$claim child to do the actual work. - -The end goal here is to keep the total number of build tasks under the -limit established by the initial make -j$n_proc call. -""" - -import errno import os -import subprocess import sys +LIB_DIR = "lib" +SRC_DIR = os.path.dirname(os.path.realpath(__file__)) -class JobserverExec: - """ - Claim all slots from make using POSIX Jobserver. - - The main methods here are: - - open(): reserves all slots; - - close(): method returns all used slots back to make; - - run(): executes a command setting PARALLELISM=<available slots jobs + 1> - """ - - def __init__(self): - """Initialize internal vars""" - self.claim = 0 - self.jobs = b"" - self.reader = None - self.writer = None - self.is_open = False - - def open(self): - """Reserve all available slots to be claimed later on""" - - if self.is_open: - return - - try: - # Fetch the make environment options. - flags = os.environ["MAKEFLAGS"] - # Look for "--jobserver=R,W" - # Note that GNU Make has used --jobserver-fds and --jobserver-auth - # so this handles all of them. - opts = [x for x in flags.split(" ") if x.startswith("--jobserver")] - - # Parse out R,W file descriptor numbers and set them nonblocking. - # If the MAKEFLAGS variable contains multiple instances of the - # --jobserver-auth= option, the last one is relevant. - fds = opts[-1].split("=", 1)[1] - - # Starting with GNU Make 4.4, named pipes are used for reader - # and writer. - # Example argument: --jobserver-auth=fifo:/tmp/GMfifo8134 - _, _, path = fds.partition("fifo:") +sys.path.insert(0, os.path.join(SRC_DIR, LIB_DIR)) - if path: - self.reader = os.open(path, os.O_RDONLY | os.O_NONBLOCK) - self.writer = os.open(path, os.O_WRONLY) - else: - self.reader, self.writer = [int(x) for x in fds.split(",", 1)] - # Open a private copy of reader to avoid setting nonblocking - # on an unexpecting process with the same reader fd. - self.reader = os.open("/proc/self/fd/%d" % (self.reader), - os.O_RDONLY | os.O_NONBLOCK) +from jobserver import JobserverExec # pylint: disable=C0415 - # Read out as many jobserver slots as possible - while True: - try: - slot = os.read(self.reader, 8) - self.jobs += slot - except (OSError, IOError) as e: - if e.errno == errno.EWOULDBLOCK: - # Stop at the end of the jobserver queue. - break - # If something went wrong, give back the jobs. - if self.jobs: - os.write(self.writer, self.jobs) - raise e - # Add a bump for our caller's reserveration, since we're just going - # to sit here blocked on our child. - self.claim = len(self.jobs) + 1 - - except (KeyError, IndexError, ValueError, OSError, IOError): - # Any missing environment strings or bad fds should result in just - # not being parallel. - self.claim = None - - self.is_open = True - - def close(self): - """Return all reserved slots to Jobserver""" - - if not self.is_open: - return - - # Return all the reserved slots. - if len(self.jobs): - os.write(self.writer, self.jobs) - - self.is_open = False - - def __enter__(self): - self.open() - return self - - def __exit__(self, exc_type, exc_value, exc_traceback): - self.close() - - def run(self, cmd): - """ - Run a command setting PARALLELISM env variable to the number of - available job slots (claim) + 1, e.g. it will reserve claim slots - to do the actual build work, plus one to monitor its children. - """ - self.open() # Ensure that self.claim is set - - # We can only claim parallelism if there was a jobserver (i.e. a - # top-level "-jN" argument) and there were no other failures. Otherwise - # leave out the environment variable and let the child figure out what - # is best. - if self.claim: - os.environ["PARALLELISM"] = str(self.claim) - - return subprocess.call(cmd) +""" +Determines how many parallel tasks "make" is expecting, as it is +not exposed via an special variables, reserves them all, runs a subprocess +with PARALLELISM environment variable set, and releases the jobs back again. +See: + https://www.gnu.org/software/make/manual/html_node/POSIX-Jobserver.html#POSIX-Jobserver +""" def main(): """Main program""" |