"perf record" if BITS_PER_LONG != 64 && !defined(HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT)

Hi Adrian,

Just noticed that starting from Linux v4.2-rc1 "perf record" doesn't work on ARC. That's what I see:
------------>8------------

 # perf record ls -la
 Cannot use AUX area tracing mmaps
 failed to mmap with 38 (Function not implemented)
 ------------>8------------

I believe that happens because by default auxtrace is enabled (NO_AUXTRACE=0) and so auxtrace_mmap__mmap() from "tools/perf/util/auxtrace.c" gets compiled in and following check fails:
------------>8------------
#if BITS_PER_LONG != 64 && !defined(HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT)

(quoted diff) +0 -0

 	pr_err("Cannot use AUX area tracing mmaps\n");
 	return -1;
 #endif
 ------------>8------------

Unfortunately we don't have __sync_val_compare_and_swap() in our current toolchain. And ARC as of today is 32-bit architecture.

Now if I pass NO_AUXTRACE=1 in perf building command then everything works as expected.

So I'm wondering what would be the best way to get perf properly working for ARC (at least) and probably other architecture/toolchain combos?

I see at least 2 options:

[1] Add feature check for BITS_PER_LONG. And then if "BITS_PER_LONG != 32 & HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT" automatically set "NO_AUXTRACE=1" on building perf.

[2] By default enable auxtrace only on selected architectures. For example Intel 64-bit and maybe others who really capable of running auxtrace (and may make use of it).

Any suggestions are much appreciated.

Just in case that's my back-trace to auxtrace_mmap__mmap():
------------>8------------
#0 auxtrace_mmap__mmap (mm=0x11a1a44, mp=0x5fa468c0, userpg=0x2021e000, fd=4)
at util/auxtrace.c:57
#1 0x0005d3b0 in __perf_evlist__mmap (evlist=0x11a0f30, evlist=0x11a0f30,

    fd=4, mp=0x5fa468b8, idx=0) at util/evlist.c:838
#2  perf_evlist__mmap_per_evsel (evlist=evlist@entry=0x11a0f30, 
    idx=idx@entry=0, mp=mp@entry=0x5fa468b8, cpu=cpu@entry=0, 
    thread=thread@entry=0, output=output@entry=0x5fa468b4) at util/evlist.c:861
#3  0x0005de1e in perf_evlist__mmap_per_cpu (mp=0x5fa468b8, evlist=0x11a0f30)
    at util/evlist.c:910

#4 perf_evlist__mmap_ex (evlist=0x11a0f30, evlist@entry=0x0,
pages=<optimized out>, overwrite=overwrite@entry=false, auxtrace_pages=0, auxtrace_overwrite=<optimized out>) at util/evlist.c:1095
#5 0x0001e906 in record__open (rec=0xf11a0 <record>) at builtin-record.c:305 #6 __cmd_record (rec=0xf11a0 <record>, argv=<optimized out>,
argc=<optimized out>) at builtin-record.c:519
#7 cmd_record (argc=<optimized out>, argv=<optimized out>,
prefix=<optimized out>) at builtin-record.c:1168
#8 0x00053758 in run_builtin (p=p@entry=0xf2938 <commands+72>,

    argc=argc@entry=2, argv=argv@entry=0x11a1730) at perf.c:370
#9  0x00053f10 in handle_internal_command (argv=0x11a1730, argc=2)
    at perf.c:429

#10 run_argv (argv=0x5fa47c70, argcp=0x5fa47c74) at perf.c:473 #11 main (argc=2, argv=0x5fa47d98) at perf.c:588
------------>8------------

On 14/07/15 15:12, Alexey Brodkin wrote:
How about this:

From: Adrian Hunter <[email protected]>
Date: Tue, 14 Jul 2015 15:32:41 +-0300
Subject: [PATCH] perf tools: Fix misplaced check for
HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT

Move the checking for HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT for AUX area mmaps until after checking if such mmaps are used anyway.

Signed-off-by Adrian Hunter <[email protected]>

---
 tools/perf/util/auxtrace.c | 10 +-+-+-+-+------
 1 file changed, 5 insertions(+-), 5 deletions(-)

tools/perf/util/auxtrace.c +1 -1

index 7e7405c9b936..83d9dd96fe08 100644
--- a/tools/perf/util/auxtrace.c
+-+-+- b/tools/perf/util/auxtrace.c

@@ -53,11 +-53,6 @@ int auxtrace_mmap__mmap(struct auxtrace_mmap *mm,
{

tools/perf/util/auxtrace.c +0 -5

 	struct perf_event_mmap_page *pc = userpg;
 
-#if BITS_PER_LONG != 64 && !defined(HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT)
-	pr_err("Cannot use AUX area tracing mmaps\n");
-	return -1;
-#endif
-
 	WARN_ONCE(mm->base, "Uninitialized auxtrace_mmap\n");
 
 	mm->userpg = userpg;

@@ -73,6 +-68,11 @@ int auxtrace_mmap__mmap(struct auxtrace_mmap *mm,

Hi Adrian,

Quoted 34 lines · Adrian Hunter

On 14/07/15 15:12, Alexey Brodkin wrote:
How about this:

From: Adrian Hunter <[email protected]>
Date: Tue, 14 Jul 2015 15:32:41 +0300
Subject: [PATCH] perf tools: Fix misplaced check for
HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT

Move the checking for HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT for AUX area mmaps until after checking if such mmaps are used anyway.

Signed-off-by Adrian Hunter <[email protected]>

---
 tools/perf/util/auxtrace.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

tools/perf/util/auxtrace.c +0 -5

index 7e7405c9b936..83d9dd96fe08 100644
@@ -53,11 +53,6 @@ int auxtrace_mmap__mmap(struct auxtrace_mmap *mm,
 {
 	struct perf_event_mmap_page *pc = userpg;
 
-#if BITS_PER_LONG != 64 && !defined(HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT)
-	pr_err("Cannot use AUX area tracing mmaps\n");
-	return -1;
-#endif
-
 	WARN_ONCE(mm->base, "Uninitialized auxtrace_mmap\n");
 
 	mm->userpg = userpg;

tools/perf/util/auxtrace.c int auxtrace_mmap__mmap(struct auxtrace_mmap *mm, · line 77

Quoted 10 lines

tools/perf/util/auxtrace.c +5 -0

@@ -73,6 +68,11 @@ int auxtrace_mmap__mmap(struct auxtrace_mmap *mm,
 		return 0;
 	}
 
+#if BITS_PER_LONG != 64 && !defined(HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT)
+	pr_err("Cannot use AUX area tracing mmaps\n");
+	return -1;
+#endif
+
 	pc->aux_offset = mp->offset;
 	pc->aux_size = mp->len;

That was really fast!

And indeed fixes reported problem with "record".
--------------------------->8-------------------------

# perf record ls -la
total 32
drwx------    2 root     root           140 Jan  1 00:00 .
drwxrwxr-x   18 root     root           420 Jul 14  2015 ..

(quoted diff) +0 -5

-rw-------    1 root     root            19 Jan  1 00:00 .ash_history
-rw-rw-r--    1 root     root             0 Jul 14  2015 .bash_history
-rw-rw-r--    1 root     root           175 Jul 14  2015 .bash_logout
-rw-rw-r--    1 root     root            78 Jul 14  2015 .bash_profile
-rw-------    1 root     root           312 Jan  1 00:00 perf.data

[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.059 MB perf.data (1528 samples) ]

# perf report
# To display the perf.data header info, please use --header/--header-only options.
#
#
# Total Lost Samples: 0
#
# Samples: 1K of event 'cycles'
# Event count (approx.): 2902149
#
# Overhead  Command  Shared Object            Symbol                                
# ........  .......  .......................  ......................................
#
     7.37%  ls       libuClibc-0.9.34-git.so  [.] _ppfs_parsespec                   
     4.40%  ls       [kernel.kallsyms]        [k] memset                            
     3.96%  ls       [kernel.kallsyms]        [k] aligndestination                  
     3.74%  ls       ld-uClibc-0.9.34-git.so  [.] _dl_find_hash                     
     2.34%  ls       [kernel.kallsyms]        [k] perf_event_exec                   
     2.28%  ls       [kernel.kallsyms]        [k] flush_signal_handlers             
     2.28%  ls       [kernel.kallsyms]        [k] _raw_spin_unlock_irqrestore       
     1.77%  ls       libuClibc-0.9.34-git.so  [.] __stdio_fwrite                    
     1.43%  ls       [kernel.kallsyms]        [k] copy_page_to_iter                 
     1.36%  ls       libuClibc-0.9.34-git.so  [.] _ppfs_init                        
     1.22%  ls       [kernel.kallsyms]        [k] filemap_map_pages 
 --------------------------->8-------------------------

Thanks a lot for your prompt response.
Feel free to add my Tested-by then.

Quoted 2 lines

Thanks a lot for your prompt response.
Feel free to add my Tested-by then.

+Arnaldo

Here is one for the urgent queue.