1 files changed, 65 insertions, 0 deletions

diff --git a/bitbake/lib/bb/runqueue.py b/bitbake/lib/bb/runqueue.py
index a513b0983b..9aa99ef4a1 100644
--- a/bitbake/lib/bb/runqueue.py
+++ b/bitbake/lib/bb/runqueue.py
@@ -24,6 +24,7 @@ import pickle
 from multiprocessing import Process
 import shlex
 import pprint
+import time
 
 bblogger = logging.getLogger("BitBake")
 logger = logging.getLogger("BitBake.RunQueue")
@@ -142,6 +143,46 @@ class RunQueueScheduler(object):
                 self.buildable.append(tid)
 
         self.rev_prio_map = None
+        self.is_pressure_usable()
+
+    def is_pressure_usable(self):
+        """
+        If monitoring pressure, return True if pressure files can be open and read. For example
+        openSUSE /proc/pressure/* files have readable file permissions but when read the error EOPNOTSUPP (Operation not supported)
+        is returned.
+        """
+        if self.rq.max_cpu_pressure or self.rq.max_io_pressure:
+            try:
+                with open("/proc/pressure/cpu") as cpu_pressure_fds, open("/proc/pressure/io") as io_pressure_fds:
+                    self.prev_cpu_pressure = cpu_pressure_fds.readline().split()[4].split("=")[1]
+                    self.prev_io_pressure = io_pressure_fds.readline().split()[4].split("=")[1]
+                    self.prev_pressure_time = time.time()
+                self.check_pressure = True
+            except:
+                bb.warn("The /proc/pressure files can't be read. Continuing build without monitoring pressure")
+                self.check_pressure = False
+        else:
+            self.check_pressure = False
+
+    def exceeds_max_pressure(self):
+        """
+        Monitor the difference in total pressure at least once per second, if
+        BB_PRESSURE_MAX_{CPU|IO} are set, return True if above threshold.
+        """
+        if self.check_pressure:
+            with open("/proc/pressure/cpu") as cpu_pressure_fds, open("/proc/pressure/io") as io_pressure_fds:
+                # extract "total" from /proc/pressure/{cpu|io}
+                curr_cpu_pressure = cpu_pressure_fds.readline().split()[4].split("=")[1]
+                curr_io_pressure = io_pressure_fds.readline().split()[4].split("=")[1]
+                exceeds_cpu_pressure =  self.rq.max_cpu_pressure and (float(curr_cpu_pressure) - float(self.prev_cpu_pressure)) > self.rq.max_cpu_pressure
+                exceeds_io_pressure =  self.rq.max_io_pressure and (float(curr_io_pressure) - float(self.prev_io_pressure)) > self.rq.max_io_pressure
+                now = time.time()
+                if now - self.prev_pressure_time > 1.0:
+                    self.prev_cpu_pressure = curr_cpu_pressure
+                    self.prev_io_pressure = curr_io_pressure
+                    self.prev_pressure_time = now
+            return (exceeds_cpu_pressure or exceeds_io_pressure)
+        return False
 
     def next_buildable_task(self):
         """
@@ -155,6 +196,12 @@ class RunQueueScheduler(object):
         if not buildable:
             return None
 
+        # Bitbake requires that at least one task be active. Only check for pressure if
+        # this is the case, otherwise the pressure limitation could result in no tasks
+        # being active and no new tasks started thereby, at times, breaking the scheduler.
+        if self.rq.stats.active and self.exceeds_max_pressure():
+            return None
+
         # Filter out tasks that have a max number of threads that have been exceeded
         skip_buildable = {}
         for running in self.rq.runq_running.difference(self.rq.runq_complete):
@@ -1700,6 +1747,8 @@ class RunQueueExecute:
 
         self.number_tasks = int(self.cfgData.getVar("BB_NUMBER_THREADS") or 1)
         self.scheduler = self.cfgData.getVar("BB_SCHEDULER") or "speed"
+        self.max_cpu_pressure = self.cfgData.getVar("BB_PRESSURE_MAX_CPU")
+        self.max_io_pressure = self.cfgData.getVar("BB_PRESSURE_MAX_IO")
 
         self.sq_buildable = set()
         self.sq_running = set()
@@ -1735,6 +1784,22 @@ class RunQueueExecute:
         if self.number_tasks <= 0:
              bb.fatal("Invalid BB_NUMBER_THREADS %s" % self.number_tasks)
 
+        lower_limit = 1.0
+        upper_limit = 1000000.0
+        if self.max_cpu_pressure:
+            self.max_cpu_pressure = float(self.max_cpu_pressure)
+            if self.max_cpu_pressure < lower_limit:
+                bb.fatal("Invalid BB_PRESSURE_MAX_CPU %s, minimum value is %s." % (self.max_cpu_pressure, lower_limit))
+            if self.max_cpu_pressure > upper_limit:
+                bb.warn("Your build will be largely unregulated since BB_PRESSURE_MAX_CPU is set to %s. It is very unlikely that such high pressure will be experienced." % (self.max_cpu_pressure))
+
+        if self.max_io_pressure:
+            self.max_io_pressure = float(self.max_io_pressure)
+            if self.max_io_pressure < lower_limit:
+                bb.fatal("Invalid BB_PRESSURE_MAX_IO %s, minimum value is %s." % (self.max_io_pressure, lower_limit))
+            if self.max_io_pressure > upper_limit:
+                bb.warn("Your build will be largely unregulated since BB_PRESSURE_MAX_IO is set to %s. It is very unlikely that such high pressure will be experienced." % (self.max_io_pressure))
+
         # List of setscene tasks which we've covered
         self.scenequeue_covered = set()
         # List of tasks which are covered (including setscene ones)