Re: [PATCH v0 21/71] perf tools: Add feature test for __sync_val_compare_and_swap

[Adrian Hunter]

On 11/12/13 21:24, Arnaldo Carvalho de Melo wrote:
> Em Wed, Dec 11, 2013 at 02:36:33PM +0200, Alexander Shishkin escreveu:
>> From: Adrian Hunter <adrian.hunter@xxxxxxxxx>
>>
>> Add a feature test for __sync_val_compare_and_swap()
>> and __sync_bool_compare_and_swap()
> 
> This makes the global feature tests to be rebuilt all the time, i.e. no
> more caching on a relatively recent system:
> 
> [acme@ssdandy linux]$ gcc -v
> Using built-in specs.
> COLLECT_GCC=/usr/bin/gcc
> COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/4.7.2/lto-wrapper
> Target: x86_64-redhat-linux
> Configured with: ../configure --prefix=/usr --mandir=/usr/share/man
> --infodir=/usr/share/info
> --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap
> --enable-shared --enable-threads=posix --enable-checking=release
> --disable-build-with-cxx --disable-build-poststage1-with-cxx
> --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions
> --enable-gnu-unique-object --enable-linker-build-id
> --with-linker-hash-style=gnu
> --enable-languages=c,c++,objc,obj-c++,java,fortran,ada,go,lto
> --enable-plugin --enable-initfini-array --enable-java-awt=gtk
> --disable-dssi --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre
> --enable-libgcj-multifile --enable-java-maintainer-mode
> --with-ecj-jar=/usr/share/java/eclipse-ecj.jar
> --disable-libjava-multilib --with-ppl --with-cloog --with-tune=generic
> --with-arch_32=i686 --build=x86_64-redhat-linux
> Thread model: posix
> gcc version 4.7.2 20121109 (Red Hat 4.7.2-8) (GCC) 
> [acme@ssdandy linux]$o
> 
> [acme@ssdandy linux]$ cat /etc/fedora-release 
> Fedora release 18 (Spherical Cow)
> 
> Can you provide more info about these gcc builtins and what is the
> minimum system where this test will succeed?

The first reference in the gcc manuals is in gcc version 4.1.2

	http://gcc.gnu.org/onlinedocs/gcc-4.1.2/gcc/

However I am not sure what will happen on all architectures.  The gcc manual
says:

	Not all operations are supported by all target processors. If a
	particular operation cannot be implemented on the target processor,
	a warning is generated and a call an external function is
	generated. The external function carries the same name as the
	built-in version, with an additional suffix ‘_n’ where n is the
	size of the data type.



> 
> In this system it works, as I can see:
> 
> ...         sync-compare-and-swap: [ on  ]
> 
> [acme@ssdandy linux]$ time make O=/tmp/build/perf -C tools/perf/
> install-bin
> make: Entering directory `/home/acme/git/linux/tools/perf'
>   BUILD:   Doing 'make -j8' parallel build
> 
> Auto-detecting system features:
> ...                     backtrace: [ on  ]
> ...                         dwarf: [ on  ]
> ...                fortify-source: [ on  ]
> ...         sync-compare-and-swap: [ on  ]
> ...                         glibc: [ on  ]
> ...                          gtk2: [ on  ]
> ...                  gtk2-infobar: [ on  ]
> ...                      libaudit: [ on  ]
> ...                        libbfd: [ on  ]
> ...                        libelf: [ on  ]
> ...             libelf-getphdrnum: [ on  ]
> ...                   libelf-mmap: [ on  ]
> ...                       libnuma: [ on  ]
> ...                       libperl: [ on  ]
> ...                     libpython: [ on  ]
> ...             libpython-version: [ on  ]
> ...                      libslang: [ on  ]
> ...                     libunwind: [ on  ]
> ...                       on-exit: [ on  ]
> ...            stackprotector-all: [ on  ]
> ...                       timerfd: [ on  ]
> 
>   GEN      perf-archive
> 
> Please check the recent changes from Jean Pihet, I think he had similar
> problems, i.e. caching stopped working.

The problem is argc and argv must be passed to
main_test_sync_compare_and_swap().  Will be fixed next
version.

> 
> - Arnaldo
> 
>  
>> Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
>> ---
>>  tools/perf/config/Makefile                                 |  5 +++++
>>  tools/perf/config/feature-checks/Makefile                  |  4 ++++
>>  tools/perf/config/feature-checks/test-all.c                |  5 +++++
>>  .../config/feature-checks/test-sync-compare-and-swap.c     | 14 ++++++++++++++
>>  4 files changed, 28 insertions(+)
>>  create mode 100644 tools/perf/config/feature-checks/test-sync-compare-and-swap.c
>>
>> diff --git a/tools/perf/config/Makefile b/tools/perf/config/Makefile
>> index bae1072..43a2879 100644
>> --- a/tools/perf/config/Makefile
>> +++ b/tools/perf/config/Makefile
>> @@ -126,6 +126,7 @@ CORE_FEATURE_TESTS =			\
>>  	backtrace			\
>>  	dwarf				\
>>  	fortify-source			\
>> +	sync-compare-and-swap		\
>>  	glibc				\
>>  	gtk2				\
>>  	gtk2-infobar			\
>> @@ -234,6 +235,10 @@ CFLAGS += -I$(LIB_INCLUDE)
>>  
>>  CFLAGS += -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE
>>  
>> +ifeq ($(feature-sync-compare-and-swap), 1)
>> +  CFLAGS += -DHAVE_SYNC_COMPARE_AND_SWAP_SUPPORT
>> +endif
>> +
>>  ifndef NO_BIONIC
>>    $(call feature_check,bionic)
>>    ifeq ($(feature-bionic), 1)
>> diff --git a/tools/perf/config/feature-checks/Makefile b/tools/perf/config/feature-checks/Makefile
>> index b8bb749..b4b7bb2 100644
>> --- a/tools/perf/config/feature-checks/Makefile
>> +++ b/tools/perf/config/feature-checks/Makefile
>> @@ -5,6 +5,7 @@ FILES=					\
>>  	test-bionic			\
>>  	test-dwarf			\
>>  	test-fortify-source		\
>> +	test-sync-compare-and-swap	\
>>  	test-glibc			\
>>  	test-gtk2			\
>>  	test-gtk2-infobar		\
>> @@ -140,6 +141,9 @@ test-backtrace:
>>  test-timerfd:
>>  	$(BUILD)
>>  
>> +test-sync-compare-and-swap:
>> +	$(BUILD)
>> +
>>  -include *.d
>>  
>>  ###############################
>> diff --git a/tools/perf/config/feature-checks/test-all.c b/tools/perf/config/feature-checks/test-all.c
>> index 9b8a544..5cfec18 100644
>> --- a/tools/perf/config/feature-checks/test-all.c
>> +++ b/tools/perf/config/feature-checks/test-all.c
>> @@ -89,6 +89,10 @@
>>  # include "test-stackprotector-all.c"
>>  #undef main
>>  
>> +#define main main_test_sync_compare_and_swap
>> +# include "test-sync-compare-and-swap.c"
>> +#undef main
>> +
>>  int main(int argc, char *argv[])
>>  {
>>  	main_test_libpython();
>> @@ -111,6 +115,7 @@ int main(int argc, char *argv[])
>>  	main_test_libnuma();
>>  	main_test_timerfd();
>>  	main_test_stackprotector_all();
>> +	main_test_sync_compare_and_swap();
>>  
>>  	return 0;
>>  }
>> diff --git a/tools/perf/config/feature-checks/test-sync-compare-and-swap.c b/tools/perf/config/feature-checks/test-sync-compare-and-swap.c
>> new file mode 100644
>> index 0000000..c34d4ca
>> --- /dev/null
>> +++ b/tools/perf/config/feature-checks/test-sync-compare-and-swap.c
>> @@ -0,0 +1,14 @@
>> +#include <stdint.h>
>> +
>> +volatile uint64_t x;
>> +
>> +int main(int argc, char *argv[])
>> +{
>> +	uint64_t old, new = argc;
>> +
>> +	argv = argv;
>> +	do {
>> +		old = __sync_val_compare_and_swap(&x, 0, 0);
>> +	} while (!__sync_bool_compare_and_swap(&x, old, new));
>> +	return old == new;
>> +}
>> -- 
>> 1.8.5.1
> 
> 

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