Re: Perf Reports Jump Instructions as Memory Access Instructions

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This is a gentle reminder to see if somebody has any thoughts/guesses.

On 2020-05-17 19:40, ahmadkhorrami wrote:

I used the following perf command to sample user space read accesses to DRAM by evince: perf record -d --call-graph dwarf -c 100 -e mem_load_uops_retired.l3_miss:uppp /opt/evince-3.28.4/bin/evince

As can be seen, I used the PEBS feature to increase the accuracy of sampling. But there are some non-memory accesses reported as memory ones. Here is one of them reported by perf script -D: 11159097179866 0xfb80 [0x1778]: PERF_RECORD_SAMPLE(IP, 0x4002): 7309/7309: 0x7ffff6d6c310 period: 10000 addr: 0x7ffff7034e50
... FP chain: nr:0
... user regs: mask 0xff0fff ABI 64-bit
.... AX    0x555555b8b4c0
.... BX    0x555555c48e10
.... CX    0x1
.... DX    0x7fffffffd988
.... SI    0x7fffffffd980
.... DI    0x555555b8b4c0
.... BP    0x258
.... SP    0x7fffffffd978
.... IP    0x7ffff6d6c310
.... FLAGS 0x20e
.... CS    0x33
.... SS    0x2b
.... R8    0x27c
.... R9    0x24
.... R10   0x2a2
.... R11   0x0
.... R12   0x258
.... R13   0x555555b8b4c0
.... R14   0x3000
.... R15   0x7ffff5747000
... ustack: size 5768, offset 0xd8
. data_src: 0x5080022
... thread: evince:7309
...... dso: /usr/lib/x86_64-linux-gnu/
evince 7309 11159.097179: 10000 mem_load_uops_retired.l3_miss:uppp: 7ffff7034e50 5080022 N/A|SNP N/A|TLB N/A|LCK N/A 7ffff6d6c310 cairo_surface_get_device_scale@plt+0x0 (/usr/lib/x86_64-linux-gnu/ 7ffff6d91029 gdk_window_create_similar_surface+0xc9 (/usr/lib/x86_64-linux-gnu/ 7ffff6d95410 gdk_window_begin_paint_internal+0x350 (/usr/lib/x86_64-linux-gnu/ 7ffff6d956f1 gdk_window_begin_draw_frame+0xc1 (/usr/lib/x86_64-linux-gnu/ 7ffff73c4942 gtk_widget_render+0xd2 (/usr/lib/x86_64-linux-gnu/ 7ffff7268858 gtk_main_do_event+0x708 (/usr/lib/x86_64-linux-gnu/ 7ffff6d79764 _gdk_event_emit+0x24 (/usr/lib/x86_64-linux-gnu/ 7ffff6d897f4 _gdk_window_process_updates_recurse_helper+0x104 (/usr/lib/x86_64-linux-gnu/ 7ffff6d8a9f5 gdk_window_process_updates_internal+0x165 (/usr/lib/x86_64-linux-gnu/ 7ffff6d8abef gdk_window_process_updates_with_mode+0x11f (/usr/lib/x86_64-linux-gnu/ 7ffff574510c g_closure_invoke+0x19c (/usr/lib/x86_64-linux-gnu/ 7ffff575805d signal_emit_unlocked_R+0xf4d (/usr/lib/x86_64-linux-gnu/ 7ffff5760714 g_signal_emit_valist+0xa74 (/usr/lib/x86_64-linux-gnu/ 7ffff576112e g_signal_emit+0x8e (/usr/lib/x86_64-linux-gnu/ 7ffff6d82ac8 gdk_frame_clock_paint_idle+0x3c8 (/usr/lib/x86_64-linux-gnu/ 7ffff6d6e07f gdk_threads_dispatch+0x1f (/usr/lib/x86_64-linux-gnu/ 7ffff546ad02 g_timeout_dispatch+0x12 (/usr/lib/x86_64-linux-gnu/
7ffff546a284 g_main_dispatch+0x154 (inlined)
7ffff546a284 g_main_context_dispatch+0x154 (/usr/lib/x86_64-linux-gnu/
7ffff546a64f g_main_context_iterate+0x1ff (inlined)
7ffff546a6db g_main_context_iteration+0x2b (/usr/lib/x86_64-linux-gnu/ 7ffff5a2be3c g_application_run+0x1fc (/usr/lib/x86_64-linux-gnu/
555555573707 main+0x447 (/opt/evince-3.28.4/bin/evince)
7ffff4a91b96 __libc_start_main+0xe6 (/lib/x86_64-linux-gnu/
555555573899 _start+0x29 (/opt/evince-3.28.4/bin/evince)

The access point is at offset 0 of the following disassembly:
Dump of assembler code for function cairo_surface_get_device_scale@plt:
0x000000000002a310 <+0>:     jmpq   *0x2c8b3a(%rip)        # 0x2f2e50
0x000000000002a316 <+6>:     pushq  $0x1c7
0x000000000002a31b <+11>:    jmpq   0x28690

This is an unconditional jump which will not lead to macrofusion.

Any help is appreciated.


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