linux-kernel - Re: [PATCH v6] perf stat: Fix wrong skipping for per-die aggregation

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Date:   Mon, 18 Jan 2021 12:16:34 +0800
From:   "Jin, Yao" <yao.jin@...ux.intel.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Jiri Olsa <jolsa@...hat.com>, jolsa@...nel.org,
        peterz@...radead.org, mingo@...hat.com,
        alexander.shishkin@...ux.intel.com, Linux-kernel@...r.kernel.org,
        ak@...ux.intel.com, kan.liang@...el.com, yao.jin@...el.com,
        ying.huang@...el.com
Subject: Re: [PATCH v6] perf stat: Fix wrong skipping for per-die aggregation

Hi Arnaldo, Jiri,

On 1/16/2021 4:31 AM, Arnaldo Carvalho de Melo wrote:
> Em Fri, Jan 15, 2021 at 05:28:14PM -0300, Arnaldo Carvalho de Melo escreveu:
>> Em Thu, Jan 14, 2021 at 08:00:32PM +0100, Jiri Olsa escreveu:
>>> On Thu, Jan 14, 2021 at 09:27:55AM +0800, Jin Yao wrote:
>>>
>>> SNIP
>>>
>>>>       2.003776312 S1-D0           1             855616 Bytes llc_misses.mem_read
>>>>       2.003776312 S1-D1           1             949376 Bytes llc_misses.mem_read
>>>>       3.006512788 S0-D0           1            1338880 Bytes llc_misses.mem_read
>>>>       3.006512788 S0-D1           1             920064 Bytes llc_misses.mem_read
>>>>       3.006512788 S1-D0           1             877184 Bytes llc_misses.mem_read
>>>>       3.006512788 S1-D1           1            1020736 Bytes llc_misses.mem_read
>>>>       4.008895291 S0-D0           1             926592 Bytes llc_misses.mem_read
>>>>       4.008895291 S0-D1           1             906368 Bytes llc_misses.mem_read
>>>>       4.008895291 S1-D0           1             892224 Bytes llc_misses.mem_read
>>>>       4.008895291 S1-D1           1             987712 Bytes llc_misses.mem_read
>>>>       5.001590993 S0-D0           1             962624 Bytes llc_misses.mem_read
>>>>       5.001590993 S0-D1           1             912512 Bytes llc_misses.mem_read
>>>>       5.001590993 S1-D0           1             891200 Bytes llc_misses.mem_read
>>>>       5.001590993 S1-D1           1             978432 Bytes llc_misses.mem_read
>>>>
>>>> On no-die system, die_id is 0, actually it's hashmap(socket,0), original behavior
>>>> is not changed.
>>>>
>>>> Reported-by: Huang Ying <ying.huang@...el.com>
>>>> Signed-off-by: Jin Yao <yao.jin@...ux.intel.com>
>>>> ---
>>>> v6:
>>>>   Fix the perf test python failure by adding hashmap.c to python-ext-sources.
>>>>
>>>>   root@...-ppc:~# ./perf test python
>>>>   19: 'import perf' in python                                         : Ok
>>>
>>> Acked-by: Jiri Olsa <jolsa@...hat.com>
>>
>> Jin, this is breaking the build in some 32-bit system, can you please
>> take a look to validate these warnings?
> 
> One such system:
> 
>    28    13.75 debian:experimental-x-mipsel  : FAIL mipsel-linux-gnu-gcc (Debian 10.2.1-3) 10.2.1 20201224
> 
>   
>>    CC       /tmp/build/perf/util/srcline.o
>> util/stat.c: In function 'pkg_id_hash':
>> util/stat.c:285:9: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
>>    return (int64_t)key & 0xffffffff;
>>           ^
>> util/stat.c: In function 'pkg_id_equal':
>> util/stat.c:291:9: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
>>    return (int64_t)key1 == (int64_t)key2;
>>           ^
>> util/stat.c:291:26: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
>>    return (int64_t)key1 == (int64_t)key2;
>>                            ^
>> util/stat.c: In function 'check_per_pkg':
>> util/stat.c:342:26: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
>>    if (hashmap__find(mask, (void *)key, NULL))
>>                            ^
>> util/stat.c:345:28: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
>>     ret = hashmap__add(mask, (void *)key, (void *)1);
>>                              ^
>>    CC       /tmp/build/perf/tests/expand-cgroup.o
> 

Thanks for reporting this build issue on 32 bit system.

In v7, I use size_t to replace uint64_t and change the hash key to 'die_id << 16 | socket_id'. I 
assume that 16 bits is enough for socket id, is it true? But if it's not true, we have to use a more 
complicated way such as allocate a structure which has die_id and socket_id and add it to hashmap.

But I'm not sure if that's necessary because I can't imagine a system which has socket id > 65535.

Thanks
Jin Yao