From: Borislav Petkov <bp@alien8.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: x86@kernel.org, rostedt@goodmis.org, hpa@zytor.com,
torvalds@linuxfoundation.org, linux-kernel@vger.kernel.org,
linux-toolchains@vger.kernel.org, jpoimboe@redhat.com,
alexei.starovoitov@gmail.com, mhiramat@kernel.org
Subject: Re: [PATCH 0/2] x86: Remove ideal_nops[]
Date: Fri, 12 Mar 2021 21:59:14 +0100 [thread overview]
Message-ID: <20210312205914.GG22098@zn.tnic> (raw)
In-Reply-To: <20210312113253.305040674@infradead.org>
On Fri, Mar 12, 2021 at 12:32:53PM +0100, Peter Zijlstra wrote:
> Since ultimate performance of a 10 year old chip (Intel Sandy Bridge, 2011) is
> simply irrelevant today, remove variable NOPs and use NOPL.
Just ran them on my SNB box:
cpu family : 6
model : 45
model name : Intel(R) Xeon(R) CPU E5-1620 0 @ 3.60GHz
stepping : 7
with the usual perf stat kernel build workload with
CONFIG_DYNAMIC_FTRACE and CONFIG_FUNCTION_TRACER where each function has
a NOP at its beginning when ftrace is disabled (thx Steve).
./tools/perf/perf stat --repeat 5 --sync --pre=/root/bin/pre-build-kernel.sh -- make -s -j9 bzImage
before: tip-master
Performance counter stats for 'make -s -j9 bzImage' (5 runs):
3,213,728.10 msec task-clock # 7.307 CPUs utilized ( +- 0.01% )
339,270 context-switches # 0.106 K/sec ( +- 0.09% )
31,472 cpu-migrations # 0.010 K/sec ( +- 0.64% )
62,070,684 page-faults # 0.019 M/sec ( +- 0.01% )
11,498,198,009,323 cycles # 3.578 GHz ( +- 0.01% ) (83.33%)
8,235,957,366,696 stalled-cycles-frontend # 71.63% frontend cycles idle ( +- 0.01% ) (83.33%)
5,976,456,688,814 stalled-cycles-backend # 51.98% backend cycles idle ( +- 0.02% ) (66.67%)
7,553,156,344,376 instructions # 0.66 insn per cycle
# 1.09 stalled cycles per insn ( +- 0.00% ) (83.33%)
1,635,468,917,524 branches # 508.901 M/sec ( +- 0.00% ) (83.34%)
51,888,292,932 branch-misses # 3.17% of all branches ( +- 0.02% ) (83.33%)
439.809 +- 0.156 seconds time elapsed ( +- 0.04% )
after: tip-master-nops
Performance counter stats for 'make -s -j9 bzImage' (5 runs):
3,217,113.67 msec task-clock # 7.307 CPUs utilized ( +- 0.03% )
339,425 context-switches # 0.106 K/sec ( +- 0.20% )
31,724 cpu-migrations # 0.010 K/sec ( +- 0.54% )
62,027,130 page-faults # 0.019 M/sec ( +- 0.01% )
11,508,779,965,901 cycles # 3.577 GHz ( +- 0.03% ) (83.34%)
8,241,212,210,440 stalled-cycles-frontend # 71.61% frontend cycles idle ( +- 0.04% ) (83.33%)
5,982,615,533,177 stalled-cycles-backend # 51.98% backend cycles idle ( +- 0.06% ) (66.66%)
7,546,407,430,314 instructions # 0.66 insn per cycle
# 1.09 stalled cycles per insn ( +- 0.00% ) (83.33%)
1,634,187,006,479 branches # 507.967 M/sec ( +- 0.00% ) (83.33%)
51,941,580,371 branch-misses # 3.18% of all branches ( +- 0.01% ) (83.33%)
440.266 +- 0.195 seconds time elapsed ( +- 0.04% )
So here's numbers talk, bullshit walks. And with those numbers no
bullshit can remain lingering around anyway.
Cheers!
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2021-03-12 21:00 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-12 11:32 [PATCH 0/2] x86: Remove ideal_nops[] Peter Zijlstra
2021-03-12 11:32 ` [PATCH 1/2] x86: Remove dynamic NOP selection Peter Zijlstra
2021-03-12 12:09 ` Peter Zijlstra
2021-03-12 20:36 ` Linus Torvalds
2024-01-20 6:58 ` Thorsten Glaser
2024-01-20 8:22 ` H. Peter Anvin
2024-01-20 16:53 ` Thorsten Glaser
2024-01-21 23:21 ` H. Peter Anvin
2024-01-21 23:58 ` Thorsten Glaser
2024-01-22 0:15 ` H. Peter Anvin
2024-01-22 0:56 ` Steven Rostedt
2024-01-22 1:17 ` Thorsten Glaser
2024-01-22 2:04 ` H. Peter Anvin
2024-01-22 2:15 ` H. Peter Anvin
2024-01-22 2:22 ` Steven Rostedt
2024-01-22 2:31 ` H. Peter Anvin
2024-01-20 17:00 ` Linus Torvalds
2024-01-20 17:19 ` Thorsten Glaser
2024-01-20 18:21 ` disassemblers (was Re: [PATCH 1/2] x86: Remove dynamic NOP selection) Thorsten Glaser
2024-01-21 22:36 ` [PATCH 1/2] x86: Remove dynamic NOP selection David Laight
2024-01-21 23:10 ` H. Peter Anvin
2021-03-12 11:32 ` [PATCH 2/2] objtool,x86: Use asm/nops.h Peter Zijlstra
2021-03-12 14:29 ` [PATCH 0/2] x86: Remove ideal_nops[] Sedat Dilek
2021-03-12 14:47 ` Borislav Petkov
2021-03-12 17:26 ` Steven Rostedt
2021-03-12 17:35 ` Sedat Dilek
2021-03-12 17:46 ` Borislav Petkov
2021-03-12 17:47 ` Steven Rostedt
2021-03-12 18:13 ` Sedat Dilek
2021-03-12 19:03 ` Sedat Dilek
2021-03-12 20:59 ` Borislav Petkov [this message]
[not found] ` <CA+icZUWSCS6vAQOXoG6nsW+Dbnogivzf+rmegCTMjz5hjE5cKQ@mail.gmail.com>
2021-03-13 8:49 ` Borislav Petkov
2021-03-13 11:23 ` Borislav Petkov
2021-03-13 12:10 ` Sedat Dilek
2021-03-13 12:15 ` Borislav Petkov
2021-03-13 12:38 ` Sedat Dilek
2021-03-13 12:49 ` Borislav Petkov
2021-03-13 12:58 ` Sedat Dilek
2021-03-13 13:29 ` Borislav Petkov
2021-03-13 13:47 ` Sedat Dilek
2021-03-15 17:04 ` Sedat Dilek
2021-03-15 17:15 ` Borislav Petkov
2021-03-15 17:19 ` Sedat Dilek
2021-03-15 17:23 ` Borislav Petkov
2021-03-15 18:10 ` Peter Zijlstra
2021-03-15 18:23 ` Sedat Dilek
2021-03-15 22:14 ` Peter Zijlstra
2021-03-16 5:56 ` Sedat Dilek
2021-03-27 12:08 ` Sedat Dilek
2021-03-27 20:02 ` Linus Torvalds
2021-03-30 12:31 ` Sedat Dilek
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