[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <45fbd9a2-78f7-4697-b3f7-b26b72f4a795@linaro.org>
Date: Wed, 4 Sep 2024 10:21:45 -0300
From: Adhemerval Zanella Netto <adhemerval.zanella@...aro.org>
To: Christophe Leroy <christophe.leroy@...roup.eu>,
"Jason A. Donenfeld" <Jason@...c4.com>, Xi Ruoyao <xry111@...111.site>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: Profiling of vdso_test_random
On 04/09/24 08:41, Christophe Leroy wrote:
> Hi,
>
> I'm done a 'perf record' on vdso_test_random reduced to vdso test only, and I get the following function usage profile.
>
> Do you see the same type of percentage on your platforms ?
>
> I would have expected most of the time to be spent in __arch_chacha20_blocks_nostack() but that's in fact not the case.
>
> # Samples: 61K of event 'task-clock:ppp'
> # Event count (approx.): 15463500000
> #
> # Overhead Command Shared Object Symbol
> # ........ ............... ................... ....................................
> #
> 57.74% vdso_test_getra [vdso] [.] __c_kernel_getrandom
> 22.49% vdso_test_getra [vdso] [.] __arch_chacha20_blocks_nostack
> 10.80% vdso_test_getra vdso_test_getrandom [.] test_vdso_getrandom
> 8.89% vdso_test_getra [vdso] [.] __kernel_getrandom
> 0.01% vdso_test_getra [kernel.kallsyms] [k] finish_task_switch.isra.0
>
After tinkering with vDSO build parameters (I had to remove the '-Bsymbolic'
and 'objdump -S') to get perf show the symbols I see on aarch64 with a reduced
vdso_test_random:
$ perf record ./vdso_test_getrandom bench-single
$ perf report
[...]
# Samples: 305 of event 'cycles:P'
# Event count (approx.): 5583551
#
# Overhead Command Shared Object Symbol
# ........ ............... ................... .........................................
#
44.27% vdso_test_getra [vdso] [.] __arch_chacha20_blocks_nostack
21.16% vdso_test_getra [vdso] [.] __kernel_getrandom
6.19% vdso_test_getra [kernel.kallsyms] [k] task_mm_cid_work
3.14% vdso_test_getra [kernel.kallsyms] [k] perf_iterate_ctx
2.96% vdso_test_getra vdso_test_getrandom [.] test_vdso_getrandom
2.48% vdso_test_getra [kernel.kallsyms] [k] __memcg_slab_free_hook
2.28% vdso_test_getra [kernel.kallsyms] [k] next_uptodate_folio
2.05% vdso_test_getra [kernel.kallsyms] [k] _raw_spin_unlock_irq
It is what I would expect, so I am not sure why might be different on powerpc.
Powered by blists - more mailing lists