From: "Martin Liška" <mliska@suse.cz>
To: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: linux-perf-users@vger.kernel.org,
lkml <linux-kernel@vger.kernel.org>, Jiri Olsa <jolsa@redhat.com>
Subject: Re: [PATCH] Properly interpret indirect call in perf annotate.
Date: Tue, 28 Aug 2018 19:55:51 +0200 [thread overview]
Message-ID: <e8c2fe77-600e-c0b1-8d14-d46982be9f51@suse.cz> (raw)
In-Reply-To: <20180828141843.GH22309@kernel.org>
On 08/28/2018 04:18 PM, Arnaldo Carvalho de Melo wrote:
> Em Tue, Aug 28, 2018 at 11:10:47AM -0300, Arnaldo Carvalho de Melo escreveu:
>> Em Mon, Aug 27, 2018 at 11:06:21AM +0200, Martin Liška escreveu:
>>> On 08/23/2018 04:12 PM, Arnaldo Carvalho de Melo wrote:
>>>> Em Thu, Aug 23, 2018 at 02:29:34PM +0200, Martin Liška escreveu:
>>>>> The patch changes interpretation of:
>>>>> callq *0x8(%rbx)
>>>>>
>>>>> from:
>>>>> 0.26 │ → callq *8
>>>>> to:
>>>>> 0.26 │ → callq *0x8(%rbx)
>
> <SNIP>
>
>>>> Please mention one or two functions where such sequence appears, so that
>>>> others can reproduce your before/after more quickly,
>
>>> Sure, there's self-contained example on can compile (-O2) and test.
>>> It's following call in test function:
>
>>> test:
>>> .LFB1:
>>> .cfi_startproc
>>> movq %rdi, %rax
>>> subq $8, %rsp
>>> .cfi_def_cfa_offset 16
>>> movq %rsi, %rdi
>>> movq %rdx, %rsi
>>> call *8(%rax) <---- here
>>> cmpl $1, %eax
>>> adcl $-1, %eax
>>> addq $8, %rsp
>>> .cfi_def_cfa_offset 8
>>> ret
>>> .cfi_endproc
>>
>> Here I'm getting:
>>
>> Samples: 2K of event 'cycles:uppp', 4000 Hz, Event count (approx.): 1808551484
>> test /home/acme/c/perf-callq [Percent: local period]
>> 0.17 │ mov %rdx,-0x28(%rbp)
>> 0.58 │ mov -0x18(%rbp),%rax
>> 7.90 │ mov 0x8(%rax),%rax
>> 8.67 │ mov -0x28(%rbp),%rcx
>> │ mov -0x20(%rbp),%rdx
>> 0.08 │ mov %rcx,%rsi
>> 6.28 │ mov %rdx,%rdi
>> 10.50 │ → callq *%rax
>> 1.67 │ mov %eax,-0x4(%rbp)
>> 11.95 │ cmpl $0x0,-0x4(%rbp)
>> 8.14 │ ↓ je 3d
>> │ mov -0x4(%rbp),%eax
>> │ sub $0x1,%eax
>> │ ↓ jmp 42
>> │3d: mov $0x0,%eax
>> 7.84 │42: leaveq
>> │ ← retq
>>
>> Without the patch, will check if something changes with it.
Hi Arnaldo.
Thanks for re-sending of the patch and for the testing. The example I sent
is dependent on version of GCC compiler.
>
> No changes with the patch, but then I did another test, ran a system
> wide record for a while, then tested without/with your patch, with
> --stdio2 redirecting to /tmp/{before,after} and got the expected
> results, see below.
>
> Thanks, applying,
Good!
Martin
>
> - Arnaldo
>
> --- /tmp/before 2018-08-28 11:16:03.238384143 -0300
> +++ /tmp/after 2018-08-28 11:15:39.335341042 -0300
> @@ -13274,7 +13274,7 @@
> ↓ jle 128
> hash_value = hash_table->hash_func (key);
> mov 0x8(%rsp),%rdi
> - 0.91 → callq *30
> + 0.91 → callq *0x30(%r12)
> mov $0x2,%r8d
> cmp $0x2,%eax
> node_hash = hash_table->hashes[node_index];
> @@ -13848,7 +13848,7 @@
> mov %r14,%rdi
> sub %rbx,%r13
> mov %r13,%rdx
> - → callq *38
> + → callq *0x38(%r15)
> cmp %rax,%r13
> 1.91 ↓ je 240
> 1b4: mov $0xffffffff,%r13d
> @@ -14026,7 +14026,7 @@
> mov %rcx,-0x500(%rbp)
> mov %r15,%rsi
> mov %r14,%rdi
> - → callq *38
> + → callq *0x38(%rax)
> mov -0x500(%rbp),%rcx
> cmp %rax,%rcx
> ↓ jne 9b0
> <SNIP tons of other such cases>
>
next prev parent reply other threads:[~2018-08-28 17:55 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-23 12:29 [PATCH] Properly interpret indirect call in perf annotate Martin Liška
2018-08-23 14:12 ` Arnaldo Carvalho de Melo
2018-08-27 9:06 ` Martin Liška
2018-08-28 14:10 ` Arnaldo Carvalho de Melo
2018-08-28 14:18 ` Arnaldo Carvalho de Melo
2018-08-28 17:55 ` Martin Liška [this message]
2018-08-23 23:00 ` Kim Phillips
2018-08-27 10:37 ` Namhyung Kim
2018-08-27 14:28 ` Martin Liška
2018-08-28 14:10 ` Arnaldo Carvalho de Melo
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