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[PATCH] cyclictest: avoid using libnuma cpumask parsing functions

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  [PATCH] cyclictest: avoid using libnuma cpumask parsing functions Clark Williams <williams@redhat.com> - 2016-04-13 22:40 +0200
    Re: [PATCH] cyclictest: avoid using libnuma cpumask parsing  functions Luiz Capitulino <lcapitulino@redhat.com> - 2016-04-14 16:40 +0200

#1378283 — [PATCH] cyclictest: avoid using libnuma cpumask parsing functions

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John,

I ran into issues with parsing cpu masks when trying to run this command:

sudo ./cyclictest -i100 -qmu -h 2000 -p95 -t1 -a3

I had previously booted a 4-core system with these boot options:

	isolcpus=3 nohz_full=3 rcu_nocbs=3

The intent was to run loads on cpus 0-2 while running cyclictest on the isolated cpu 3. 

Unfortunately, the libnuma function numa_parse_cpumask() (which we use when it's available) seems to check the current affinity mask and fails the parse if any of the cpus in the input string are not in the current affinity mask. I find this "unhelpful" when trying to place a measurement thread on an isolated cpu. 

This patch removes the wrapper function which uses libnuma cpumask parsing functions and instead uses the parser function we wrote for when libnuma is not available. 

Signed-off-by: Clark Williams <williams@redhat.com>
---
 src/cyclictest/rt_numa.h | 82 ++++++++++++++++++++++--------------------------
 1 file changed, 38 insertions(+), 44 deletions(-)

diff --git a/src/cyclictest/rt_numa.h b/src/cyclictest/rt_numa.h
index ec2994314e80..d65cd421863b 100644
--- a/src/cyclictest/rt_numa.h
+++ b/src/cyclictest/rt_numa.h
@@ -32,6 +32,12 @@ static int numa = 0;
 #define LIBNUMA_API_VERSION 1
 #endif
 
+#ifndef BITS_PER_LONG
+#define BITS_PER_LONG    (8*sizeof(long))
+#endif
+
+
+
 static void *
 threadalloc(size_t size, int node)
 {
@@ -89,22 +95,6 @@ static inline unsigned int rt_numa_bitmask_isbitset( const struct bitmask *mask,
 	return numa_bitmask_isbitset(mask,i);
 }
 
-static inline struct bitmask* rt_numa_parse_cpustring(const char* s,
-	int max_cpus)
-{
-#ifdef HAVE_PARSE_CPUSTRING_ALL		/* Currently not defined anywhere.  No
-					   autotools build. */
-	return numa_parse_cpustring_all(s);
-#else
-	/* We really need numa_parse_cpustring_all(), so we can assign threads
-	 * to cores which are part of an isolcpus set, but early 2.x versions of
-	 * libnuma do not have this function.  A work around should be to run
-	 * your command with e.g. taskset -c 9-15 <command>
-	 */
-	return numa_parse_cpustring((char *)s);
-#endif
-}
-
 static inline void rt_bitmask_free(struct bitmask *mask)
 {
 	numa_bitmask_free(mask);
@@ -157,32 +147,6 @@ static inline unsigned int rt_numa_bitmask_isbitset( const struct bitmask *mask,
 	return (bit != 0);
 }
 
-static inline struct bitmask* rt_numa_parse_cpustring(const char* s,
-	int max_cpus)
-{
-	int cpu;
-	struct bitmask *mask = NULL;
-	cpu = atoi(s);
-	if (0 <= cpu && cpu < max_cpus) {
-		mask = malloc(sizeof(*mask));
-		if (mask) {
-			/* Round up to integral number of longs to contain
-			 * max_cpus bits */
-			int nlongs = (max_cpus+BITS_PER_LONG-1)/BITS_PER_LONG;
-
-			mask->maskp = calloc(nlongs, sizeof(long));
-			if (mask->maskp) {
-				mask->maskp[cpu/BITS_PER_LONG] |=
-					(1UL << (cpu % BITS_PER_LONG));
-				mask->size = max_cpus;
-			} else {
-				free(mask);
-				mask = NULL;
-			}
-		}
-	}
-	return mask;
-}
 
 static inline void rt_bitmask_free(struct bitmask *mask)
 {
@@ -204,8 +168,6 @@ struct bitmask {
     unsigned long size; /* number of bits in the map */
     unsigned long *maskp;
 };
-#define BITS_PER_LONG    (8*sizeof(long))
-
 static inline void *threadalloc(size_t size, int n) { return malloc(size); }
 static inline void threadfree(void *ptr, size_t s, int n) { free(ptr); }
 static inline void rt_numa_set_numa_run_on_node(int n, int c) { }
@@ -280,4 +242,36 @@ static inline unsigned int rt_numa_bitmask_count(const struct bitmask *mask)
 	return num_bits;
 }
 
+/*
+ * Use this instead of a wrapper for libnuma functions.
+ * The libnuma function numa_parse_cpustring() checks the affinity mask
+ * and fails if an input cpu is not in the mask. This of course sucks when
+ * trying to place a thread on an isolated cpu. Avoid libnuma parsing functions
+ */
+static inline struct bitmask* rt_numa_parse_cpustring(const char* s,
+	int max_cpus)
+{
+	int cpu;
+	struct bitmask *mask = NULL;
+	cpu = atoi(s);
+	if (0 <= cpu && cpu < max_cpus) {
+		mask = malloc(sizeof(*mask));
+		if (mask) {
+			/* Round up to integral number of longs to contain
+			 * max_cpus bits */
+			int nlongs = (max_cpus+BITS_PER_LONG-1)/BITS_PER_LONG;
+
+			mask->maskp = calloc(nlongs, sizeof(long));
+			if (mask->maskp) {
+				mask->maskp[cpu/BITS_PER_LONG] |=
+					(1UL << (cpu % BITS_PER_LONG));
+				mask->size = max_cpus;
+			} else {
+				free(mask);
+				mask = NULL;
+			}
+		}
+	}
+	return mask;
+}
 #endif	/* _RT_NUMA_H */
-- 
2.5.5

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#1378940 — Re: [PATCH] cyclictest: avoid using libnuma cpumask parsing functions

On Wed, 13 Apr 2016 15:37:00 -0500
Clark Williams <williams@redhat.com> wrote:

> John,
> 
> I ran into issues with parsing cpu masks when trying to run this command:
> 
> sudo ./cyclictest -i100 -qmu -h 2000 -p95 -t1 -a3
> 
> I had previously booted a 4-core system with these boot options:
> 
> 	isolcpus=3 nohz_full=3 rcu_nocbs=3
> 
> The intent was to run loads on cpus 0-2 while running cyclictest on the isolated cpu 3. 
> 
> Unfortunately, the libnuma function numa_parse_cpumask() (which we use when it's available) seems to check the current affinity mask and fails the parse if any of the cpus in the input string are not in the current affinity mask. I find this "unhelpful" when trying to place a measurement thread on an isolated cpu. 
> 
> This patch removes the wrapper function which uses libnuma cpumask parsing functions and instead uses the parser function we wrote for when libnuma is not available. 

There's an alternative solution that I was working on some time ago,
which is having a simple configure script. This is usually done
by simple projects that don't need a full blown autoconf machinery.

The patch below adds such a script. It detects librt, libpthread and
libnuma. It solves the problem you mention and it removes hardcoded
lib details from the Makefile.

If there's interest for this solution I can finish it and post for
inclusion.

From 4228140e9dbb7fbb1bb495663ae3d896fc447f8f Mon Sep 17 00:00:00 2001
From: Luiz Capitulino <lcapitulino@redhat.com>
Date: Tue, 23 Feb 2016 15:53:43 -0500
Subject: [PATCH] add configure script

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
---
 .gitignore |   1 +
 Makefile   |  22 ++----------
 configure  | 116 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 120 insertions(+), 19 deletions(-)
 create mode 100755 configure

diff --git a/.gitignore b/.gitignore
index ceee8bf..5b3e4cc 100644
--- a/.gitignore
+++ b/.gitignore
@@ -34,3 +34,4 @@ SRPMS
 rt-tests.spec
 tags
 TAGS
+config.mk
diff --git a/Makefile b/Makefile
index 280fd3b..dad0175 100644
--- a/Makefile
+++ b/Makefile
@@ -1,3 +1,5 @@
+include config.mk
+
 VERSION = 0.97
 CC?=$(CROSS_COMPILE)gcc
 AR?=$(CROSS_COMPILE)ar
@@ -17,7 +19,6 @@ sources = cyclictest.c \
 	  svsematest.c
 
 TARGETS = $(sources:.c=)
-LIBS	= -lrt -lpthread
 RTTESTLIB = -lrttest -L$(OBJDIR)
 EXTRA_LIBS ?= -ldl	# for get_cpu
 DESTDIR	?=
@@ -48,26 +49,9 @@ ostype := $(lastword $(subst -, ,$(dumpmachine)))
 machinetype := $(shell echo $(dumpmachine)| \
     sed -e 's/-.*//' -e 's/i.86/i386/' -e 's/mips.*/mips/' -e 's/ppc.*/powerpc/')
 
-# The default is to assume you have libnuma installed, which is fine to do
-# even on non-numa machines. If you don't want to install the numa libs, for
-# example, they might not be available in an embedded environment, then
-# compile with
-# make NUMA=0
-ifneq ($(filter x86_64 i386 ia64 mips powerpc,$(machinetype)),)
-NUMA 	:= 1
-endif
-
-# The default is to assume that you only have numa_parse_cpustring
-# If you are sure you have a version of libnuma with numa_parse_cpustring_all
-# then compile with
-# make HAVE_PARSE_CPUSTRING_ALL=1
-ifeq ($(NUMA),1)
-	CFLAGS += -DNUMA
-	NUMA_LIBS = -lnuma
 ifdef HAVE_PARSE_CPUSTRING_ALL
 	CFLAGS += -DHAVE_PARSE_CPUSTRING_ALL
 endif
-endif
 
 include src/arch/android/Makefile
 
@@ -100,7 +84,7 @@ $(OBJDIR):
 -include $(addprefix $(OBJDIR)/,$(sources:.c=.d))
 
 cyclictest: $(OBJDIR)/cyclictest.o $(OBJDIR)/librttest.a
-	$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $< $(LIBS) $(RTTESTLIB) $(NUMA_LIBS)
+	$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $< $(LIBS) $(RTTESTLIB)
 
 signaltest: $(OBJDIR)/signaltest.o $(OBJDIR)/librttest.a
 	$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $< $(LIBS) $(RTTESTLIB)
diff --git a/configure b/configure
new file mode 100755
index 0000000..1d17ef9
--- /dev/null
+++ b/configure
@@ -0,0 +1,116 @@
+#!/bin/sh
+
+build_config=config.mk
+temp_dir=$(mktemp -d)
+temp_file=$temp_dir/file.c
+
+LIBS=
+NUMA_LIBS=
+EXTRA_CFLAGS=
+has_numa=n
+has_numa_cpustring_all=n
+
+build_test()
+{
+	local libs=$*
+	local ret=
+
+	cd $temp_dir
+	cc -o prog $temp_file $libs 2> /dev/null
+	ret=$?
+	cd - > /dev/null
+	return $ret
+}
+
+#
+# -lpthread
+#
+pthread_lib=-lpthread
+
+cat > $temp_file << EOF
+#include <pthread.h>
+static void *func(void *p) { return NULL; }
+int main(void) {
+	pthread_t thread;
+	pthread_create(&thread, 0, func, 0);
+	return 0;
+}
+EOF
+
+if ! build_test $pthread_lib; then
+	echo ERROR: missing pthread library
+	exit 1
+else
+	LIBS="$LIBS $pthread_lib"
+fi
+
+#
+# -lrt
+#
+rt_lib=-lrt
+
+cat > $temp_file << EOF
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+int main(void) {
+	shm_open("", 0, 0);
+	return 0;
+}
+EOF
+
+if ! build_test $rt_lib; then
+	echo ERROR: missing rt library
+	exit 1
+else
+	LIBS="$LIBS $rt_lib"
+fi
+
+#
+# -lnuma
+#
+numa_lib=-lnuma
+
+cat > $temp_file << EOF
+#include <numa.h>
+int main(void) {
+	numa_available();
+	return 0;
+}
+EOF
+
+if build_test $numa_lib; then
+	LIBS="$LIBS $numa_lib"
+	EXTRA_CFLAGS="$EXTRA_CFLAGS -DNUMA"
+	has_numa=y
+fi
+
+#
+# numa_parse_cpustring_all
+#
+if [ $has_numa = "y" ]; then
+
+	cat > $temp_file << EOF
+#include <numa.h>
+int main(void) {
+	numa_parse_cpustring_all("");
+	return 0;
+}
+EOF
+
+	if build_test $numa_lib; then
+		has_numa_cpustring_all=y;
+	fi
+fi
+
+#
+# Write $build_config
+#
+echo "LIBS = $LIBS" > $build_config
+echo "EXTRA_CFLAGS = $EXTRA_CFLAGS" >> $build_config
+
+if [ "$has_numa_cpustring_all" = "y" ]; then
+	echo "HAVE_PARSE_CPUSTRING_ALL := 1" >> $build_config
+fi
+
+rm -rf $temp_dir
-- 
2.5.5

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