Added support for passing an (impure) NIX_BUILD_CORES variable to build expressions.

This patch adds the configuration file variable "build-cores" and the
command line argument "--cores". These settings specify the number of
CPU cores to utilize for parallel building within a job, i.e. by passing
an appropriate "-j" flag to GNU Make. The default value is 1, which
means that parallel building is *disabled*. If the number of build cores
is specified as 0 (synonymously: "guess" or "auto"), then the actual
value is supposed to be auto-detected by builders at run-time, i.e by
calling the nproc(1) utility from coreutils.

The environment variable $NIX_BUILD_CORES is available to builders, but
the contents of that variable does *not* influence the hash that goes
into the $out store path, i.e. the number of build cores to be utilized
can be changed at will without requiring any re-builds.
This commit is contained in:
Peter Simons 2010-06-23 14:34:08 +00:00
parent 819548d92f
commit 8b7f8b56f1
5 changed files with 35 additions and 0 deletions

View file

@ -59,6 +59,18 @@
#build-max-jobs = 1
### Option `build-cores'
#
# This option defines the number of CPU cores to utilize in parallel
# within a build job, i.e. by passing an appropriate `-jN' flag to
# GNU make. The default is 1, meaning that parallel building within
# jobs is disabled. Passing the special values `0', `auto', or
# `guess' causes Nix to try and auto-detect the number of available
# cores on the local host. This setting can be overridden using the
# `--cores' command line switch.
#build-cores = 1
### Option `build-max-silent-time'
#
# This option defines the maximum number of seconds that a builder can

View file

@ -135,6 +135,12 @@ static void initAndRun(int argc, char * * argv)
/* Get some settings from the configuration file. */
thisSystem = querySetting("system", SYSTEM);
maxBuildJobs = queryIntSetting("build-max-jobs", 1);
string tmp = querySetting("build-cores", "/UNDEFINED");
std::transform(tmp.begin(), tmp.end(), tmp.begin(), tolower);
if (tmp == "auto" || tmp == "guess")
buildCores = 0;
else
buildCores = queryIntSetting("build-cores", 1);
maxSilentTime = queryIntSetting("build-max-silent-time", 0);
/* Catch SIGINT. */
@ -226,6 +232,14 @@ static void initAndRun(int argc, char * * argv)
tryFallback = true;
else if (arg == "--max-jobs" || arg == "-j")
maxBuildJobs = getIntArg<unsigned int>(arg, i, args.end());
else if (arg == "--cores") {
string tmp = *(++i);
std::transform(tmp.begin(), tmp.end(), tmp.begin(), tolower);
if (tmp == "auto" || tmp == "guess")
buildCores = 0u;
else
buildCores = getIntArg<unsigned int>(arg, --i, args.end());
}
else if (arg == "--readonly-mode")
readOnlyMode = true;
else if (arg == "--max-silent-time")

View file

@ -1411,6 +1411,9 @@ void DerivationGoal::startBuilder()
in the store or in the build directory). */
env["NIX_STORE"] = nixStore;
/* The maximum number of cores to utilize for parallel building. */
env["NIX_BUILD_CORES"] = (format("%d") % buildCores).str();
/* Add all bindings specified in the derivation. */
foreach (StringPairs::iterator, i, drv.env)
env[i->first] = i->second;

View file

@ -22,6 +22,7 @@ bool keepGoing = false;
bool tryFallback = false;
Verbosity buildVerbosity = lvlInfo;
unsigned int maxBuildJobs = 1;
unsigned int buildCores = 1;
bool readOnlyMode = false;
string thisSystem = "unset";
time_t maxSilentTime = 0;

View file

@ -55,6 +55,11 @@ extern Verbosity buildVerbosity;
/* Maximum number of parallel build jobs. 0 means unlimited. */
extern unsigned int maxBuildJobs;
/* Number of CPU cores to utilize in parallel within a build, i.e. by passing
this number to Make via '-j'. 0 means that the number of actual CPU cores on
the local host ought to be auto-detected. */
extern unsigned int buildCores;
/* Read-only mode. Don't copy stuff to the store, don't change the
database. */
extern bool readOnlyMode;