[zorg] Throttle down parallelism of AArch64 and AArch32 libcxx bots

[maxim-kuvyrkov]

Summary

... to workaround timing assumptions in libcxx testsuites.
A number of locking tests assert that they get a lock under certain time
(50ms), which can fail under heavy load. Throttling down parallelism
should fix that because each bot is guaranteed ~2 CPUs (out of 64),
which is plenty for single-threaded operation.

[maxim-kuvyrkov]

Gentle ping? This is a fairly simple patch. Without it I can't enable linaro-armv8-01-arm-libcxx* bots.

zorg/trunk/buildbot/osuosl/master/config/slaves.py

return [
         create_slave("linaro-tk1-08", properties={'jobs' : 4}, max_builds=1),
         create_slave("linaro-tk1-09", properties={'jobs' : 4}, max_builds=1),
         create_slave("linaro-armv8-01-arm-lnt", properties={'jobs' : 64}, max_builds=1),
         create_slave("linaro-armv8-01-arm-selfhost-neon", properties={'jobs' : 64}, max_builds=1),
         create_slave("linaro-armv8-01-arm-quick", properties={'jobs' : 64}, max_builds=1),
         create_slave("linaro-armv8-01-arm-global-isel", properties={'jobs' : 64}, max_builds=1),
         create_slave("linaro-armv8-01-arm-full", properties={'jobs' : 64}, max_builds=1),
         create_slave("linaro-armv8-01-arm-full-selfhost", properties={'jobs' : 64}, max_builds=1),
-        create_slave("linaro-armv8-01-arm-libcxx", properties={'jobs' : 64}, max_builds=1),
-        create_slave("linaro-armv8-01-arm-libcxx-noeh", properties={'jobs' : 64}, max_builds=1),
+        # Libcxx testsuite has tests with timing assumptions.  Run single-threaded to make
+        # sure we have plenty CPU cycle to satisfy timing assumptions.
+        create_slave("linaro-armv8-01-arm-libcxx", properties={'jobs' : 1}, max_builds=1),
+        create_slave("linaro-armv8-01-arm-libcxx-noeh", properties={'jobs' : 1}, max_builds=1),
 
         # AArch64 Linaro slaves
         create_slave("linaro-apm-01", properties={'jobs' : 8}, max_builds=1),
         create_slave("linaro-apm-02", properties={'jobs' : 8}, max_builds=1),
         create_slave("linaro-apm-03", properties={'jobs' : 8}, max_builds=1),
         create_slave("linaro-apm-04", properties={'jobs' : 8}, max_builds=1),
         create_slave("linaro-apm-05", properties={'jobs' : 8}, max_builds=1),
         create_slave("linaro-apm-06", properties={'jobs' : 8}, max_builds=1),
         create_slave("linaro-armv8-01-aarch64-quick", properties={'jobs' : 64}, max_builds=1),
         create_slave("linaro-armv8-01-aarch64-full", properties={'jobs' : 64}, max_builds=1),
         create_slave("linaro-armv8-01-aarch64-global-isel", properties={'jobs' : 64}, max_builds=1),
         create_slave("linaro-armv8-01-aarch64-lld", properties={'jobs' : 64}, max_builds=1),
-        create_slave("linaro-armv8-01-aarch64-libcxx", properties={'jobs' : 64}, max_builds=1),
-        create_slave("linaro-armv8-01-aarch64-libcxx-noeh", properties={'jobs' : 64}, max_builds=1),
+        # Libcxx testsuite has tests with timing assumptions.  Run single-threaded to make
+        # sure we have plenty CPU cycle to satisfy timing assumptions.
+        create_slave("linaro-armv8-01-aarch64-libcxx", properties={'jobs' : 1}, max_builds=1),
+        create_slave("linaro-armv8-01-aarch64-libcxx-noeh", properties={'jobs' : 1}, max_builds=1),
 
         # AMD Athlon(tm) 64 X2 Dual Core 3800+, Ubuntu x86_64
         create_slave("grosser1", properties={'jobs': 2}, max_builds=1),
 
         # Intel(R) Core(TM)2 Quad CPU Q6600  @ 2.40GHz, Debian x86_64 GNU/Linux
         #create_slave("grosser2", properties={'jobs': 4}, max_builds=1),
 
         # Polly perf servers