Re: S390 support to be removed from next oprofile release

On 08/04/2014 01:23 PM, Andreas Arnez wrote:
> On Fri, Aug 01 2014, Maynard Johnson wrote:
> 
>> On 08/01/2014 08:22 AM, Maynard Johnson wrote:
>>> On 08/01/2014 06:16 AM, Andreas Arnez wrote:
>>>> On Thu, Jul 31 2014, Andreas Arnez wrote:
>>>>
>>>>> [...] I think I can provide you with a patch that implements
>>>>> _get_s390_cpu_type() by tomorrow.
>>>>
>>>> OK, here you go.  Note that I only unit-tested the new function
>>>> _get_s390_cpu_type(), but I didn't build (and test) oprofile with this
>>>> change.
>>>
>>> Patch committed.  Pretty simple. Now operf and ocount support s390.  Thanks!
>> Andreas,
>> I have a question that is tangentially related to this patch.  How did you test it?
> 
> As I said, I didn't.  Today I've grabbed a machine with hardware
> sampling enabled and tried it out, and it failed -- maybe not
> surprisingly.  Note that I haven't done anyting with perf or oprofile
> yet, so there might be lots of user errors involved.
> 
> The problems I stumbled upon:
> 
> * The linker complained about an undefined symbol "pthread_key_create".
>   This seems to always happen when linking a C++ program that has static
>   string initializers with librt but without libpthread.
> 
> * "operf" didn't like the fact that the address of "_text" in kallsyms
>   is zero on S390.
> 
> * As you indicated, the default event selection seemed to (wrongly) pick
>   timer mode.
> 
> So I've performed the changes below, but operf still fails:

Andreas, those changes in the patch below look fine, but could you please just add
a "Signed-off-by:" line to make it official.

> 
> [root@p23lp54 arnez]# operf --verbose=all -s
> Using samples dir /root/arnez/oprofile_data/samples
> kernel_start = 0; kernel_end = 778848
> operf_record ctor using output fd 7
> calling sigaction
> calling setup
> operf_record::setup() for system-wide profiling
> op_get_process_info
> calling perf_event_open for pid -1 on 24 cpus
> perf_event_open failed: No such file or directory
This is the perf_event_open syscall failing with ENOENT when we pass "-1" for both
'pid' and 'cpu' arguments for when we want to do system-wide profiling.  You'd have
to look at the kernel to see why it fails (probably start with arch/s390/kernel/perf_cpum_sf.c).
I would bet a non-system-wide profile would work OK (e.g., 'operf /bin/true').

-Maynard
> perf_event_open failed with No such file or directory
> Caught runtime_error: Internal Error.  Perf event setup failed.
> operf record process failure; exiting
> Error running profiler
> 
> Any hint how to quickly get to the bottom of this?
> 
> Thanks,
> Andreas
> 
> -- >8 --
> Subject: [PATCH] Preliminary fixes to get oprofile running on S390
> From: Andreas Arnez <[email protected]>
> 
> diff --git a/libop/op_events.c b/libop/op_events.c
> index bbeb212..33028b4 100644
> --- a/libop/op_events.c
> +++ b/libop/op_events.c
> @@ -1323,14 +1323,14 @@ void op_default_event(op_cpu cpu_type, struct op_default_event_descr * descr)
>  		case CPU_S390_Z10:
>  		case CPU_S390_Z196:
>  		case CPU_S390_ZEC12:
> - 			if (op_get_nr_counters(cpu_type) > 1) {
> - 				descr->name = "HWSAMPLING";
> - 				descr->count = 4127518;
> - 			} else {
> - 				descr->name = TIMER_EVENT_NAME;
> - 				descr->count = 10000;
> - 			}
> -  			break;
> +			if (op_get_nr_counters(cpu_type) > 1) {
> +				descr->name = TIMER_EVENT_NAME;
> +				descr->count = 10000;
> +			} else {
> +				descr->name = "HWSAMPLING";
> +				descr->count = 4127518;
> +			}
> +			break;
> 
>  		case CPU_TILE_TILE64:
>  		case CPU_TILE_TILEPRO:
> diff --git a/pe_counting/Makefile.am b/pe_counting/Makefile.am
> index c46fd74..b803134 100644
> --- a/pe_counting/Makefile.am
> +++ b/pe_counting/Makefile.am
> @@ -19,7 +19,7 @@ AM_CXXFLAGS = @OP_CXXFLAGS@
>  AM_LDFLAGS = @OP_LDFLAGS@
> 
>  bin_PROGRAMS = ocount
> -ocount_LDADD = -lrt ../libpe_utils/libpe_utils.a \
> +ocount_LDADD = -lrt -lpthread ../libpe_utils/libpe_utils.a \
>  	../libpe_utils/libpe_utils.a \
>  	../libop/libop.a \
>  	../libutil/libutil.a \
> diff --git a/pe_profiling/operf.cpp b/pe_profiling/operf.cpp
> index 51f55a5..efc3c65 100644
> --- a/pe_profiling/operf.cpp
> +++ b/pe_profiling/operf.cpp
> @@ -1099,7 +1099,7 @@ static bool _add_kernel_entry(string start_addr_str, string end_addr_str, string
>  		return false;
>  	}
> 
> -	if ((start_addr == 0) || (end_addr == 0)) {
> +	if ((start_addr == 0) && (end_addr == 0)) {
>  		no_vmlinux = true;
>  		cerr << "Kernel profiling is not possible with current system "
>  		     << "config." << endl
> 


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