torture: Auto-size SCF and scaling runs based on number of CPUs

This commit improves torture.sh flexibility by autoscaling the number
of CPUs to be used in variable-CPUs torture tests, including scftorture,
refscale, rcuscale, and kvfree.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/testing/selftests/rcutorture/bin/torture.sh

@@ -19,6 +19,11 @@ PATH=${KVM}/bin:$PATH; export PATH
 
 TORTURE_ALLOTED_CPUS="`identify_qemu_vcpus`"
 MAKE_ALLOTED_CPUS=$((TORTURE_ALLOTED_CPUS*2))
+HALF_ALLOTED_CPUS=$((TORTURE_ALLOTED_CPUS/2))
+if test "$HALF_ALLOTED_CPUS" -lt 1
+then
+	HALF_ALLOTED_CPUS=1
+fi
 
 # Default duration and apportionment.
 duration_base=10
@@ -291,8 +296,8 @@ fi
 
 if test "$do_scftorture" = "yes"
 then
-	torture_bootargs="scftorture.nthreads=224 torture.disable_onoff_at_boot"
-	torture_set "scftorture" tools/testing/selftests/rcutorture/bin/kvm.sh --torture scf --allcpus --duration "$duration_scftorture" --kconfig "CONFIG_NR_CPUS=224" --trust-make
+	torture_bootargs="scftorture.nthreads=$HALF_ALLOTED_CPUS torture.disable_onoff_at_boot"
+	torture_set "scftorture" tools/testing/selftests/rcutorture/bin/kvm.sh --torture scf --allcpus --duration "$duration_scftorture" --kconfig "CONFIG_NR_CPUS=$HALF_ALLOTED_CPUS" --trust-make
 fi
 
 if test "$do_refscale" = yes
@@ -303,8 +308,8 @@ else
 fi
 for prim in $primlist
 do
-	torture_bootargs="refscale.scale_type="$prim" refscale.nreaders=224 refscale.loops=10000 refscale.holdoff=20 torture.disable_onoff_at_boot"
-	torture_set "refscale-$prim" tools/testing/selftests/rcutorture/bin/kvm.sh --torture refscale --allcpus --duration 5 --kconfig "CONFIG_NR_CPUS=224" --trust-make
+	torture_bootargs="refscale.scale_type="$prim" refscale.nreaders=$HALF_ALLOTED_CPUS refscale.loops=10000 refscale.holdoff=20 torture.disable_onoff_at_boot"
+	torture_set "refscale-$prim" tools/testing/selftests/rcutorture/bin/kvm.sh --torture refscale --allcpus --duration 5 --kconfig "CONFIG_NR_CPUS=$HALF_ALLOTED_CPUS" --trust-make
 done
 
 if test "$do_rcuscale" = yes
@@ -315,14 +320,14 @@ else
 fi
 for prim in $primlist
 do
-	torture_bootargs="rcuscale.scale_type="$prim" rcuscale.nwriters=224 rcuscale.holdoff=20 torture.disable_onoff_at_boot"
-	torture_set "rcuscale-$prim" tools/testing/selftests/rcutorture/bin/kvm.sh --torture rcuscale --allcpus --duration 5 --kconfig "CONFIG_NR_CPUS=224" --trust-make
+	torture_bootargs="rcuscale.scale_type="$prim" rcuscale.nwriters=$HALF_ALLOTED_CPUS rcuscale.holdoff=20 torture.disable_onoff_at_boot"
+	torture_set "rcuscale-$prim" tools/testing/selftests/rcutorture/bin/kvm.sh --torture rcuscale --allcpus --duration 5 --kconfig "CONFIG_NR_CPUS=$HALF_ALLOTED_CPUS" --trust-make
 done
 
 if test "$do_kvfree" = "yes"
 then
 	torture_bootargs="rcuscale.kfree_rcu_test=1 rcuscale.kfree_nthreads=16 rcuscale.holdoff=20 rcuscale.kfree_loops=10000 torture.disable_onoff_at_boot"
-	torture_set "rcuscale-kvfree" tools/testing/selftests/rcutorture/bin/kvm.sh --torture rcuscale --allcpus --duration 10 --kconfig "CONFIG_NR_CPUS=224" --trust-make
+	torture_set "rcuscale-kvfree" tools/testing/selftests/rcutorture/bin/kvm.sh --torture rcuscale --allcpus --duration 10 --kconfig "CONFIG_NR_CPUS=$HALF_ALLOTED_CPUS" --trust-make
 fi
 
 echo " --- " $scriptname $args