From: Borislav Petkov <bp@alien8.de>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>, X86 ML <x86@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Denys Vlasenko <vda.linux@googlemail.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Brian Gerst <brgerst@gmail.com>,
Denys Vlasenko <dvlasenk@redhat.com>,
Ingo Molnar <mingo@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Oleg Nesterov <oleg@redhat.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Alexei Starovoitov <ast@plumgrid.com>,
Will Drewry <wad@chromium.org>, Kees Cook <keescook@chromium.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86_64, asm: Work around AMD SYSRET SS descriptor attribute issue
Date: Mon, 27 Apr 2015 16:39:05 +0200 [thread overview]
Message-ID: <20150427143905.GK6774@pd.tnic> (raw)
In-Reply-To: <CALCETrWvqyCYOzCYXz7ZnzaM0obbidqo5CxVp2Hn1ELEiC3m3g@mail.gmail.com>
On Sun, Apr 26, 2015 at 04:39:38PM -0700, Andy Lutomirski wrote:
> I know it would be ugly, but would it be worth saving two bytes by
> using ALTERNATIVE "jmp 1f", "shl ...", ...?
Damn, it is actually visible even that saving the unconditional forward
JMP makes the numbers marginally nicer (E: row). So I guess we'll be
dropping the forward JMP too.
A: 2835570.145246 cpu-clock (msec) ( +- 0.02% ) [100.00%]
B: 2833364.074970 cpu-clock (msec) ( +- 0.04% ) [100.00%]
C: 2834708.335431 cpu-clock (msec) ( +- 0.02% ) [100.00%]
D: 2835055.118431 cpu-clock (msec) ( +- 0.01% ) [100.00%]
E: 2833115.118624 cpu-clock (msec) ( +- 0.06% ) [100.00%]
A: 2835570.099981 task-clock (msec) # 3.996 CPUs utilized ( +- 0.02% ) [100.00%]
B: 2833364.073633 task-clock (msec) # 3.996 CPUs utilized ( +- 0.04% ) [100.00%]
C: 2834708.350387 task-clock (msec) # 3.996 CPUs utilized ( +- 0.02% ) [100.00%]
D: 2835055.094383 task-clock (msec) # 3.996 CPUs utilized ( +- 0.01% ) [100.00%]
E: 2833115.145292 task-clock (msec) # 3.996 CPUs utilized ( +- 0.06% ) [100.00%]
A: 5,591,213,166,613 cycles # 1.972 GHz ( +- 0.03% ) [75.00%]
B: 5,585,023,802,888 cycles # 1.971 GHz ( +- 0.03% ) [75.00%]
C: 5,587,983,212,758 cycles # 1.971 GHz ( +- 0.02% ) [75.00%]
D: 5,584,838,532,936 cycles # 1.970 GHz ( +- 0.03% ) [75.00%]
E: 5,583,979,727,842 cycles # 1.971 GHz ( +- 0.05% ) [75.00%]
cycles is the lowest, nice.
A: 3,106,707,101,530 instructions # 0.56 insns per cycle ( +- 0.01% ) [75.00%]
B: 3,106,632,251,528 instructions # 0.56 insns per cycle ( +- 0.00% ) [75.00%]
C: 3,106,265,958,142 instructions # 0.56 insns per cycle ( +- 0.00% ) [75.00%]
D: 3,106,294,801,185 instructions # 0.56 insns per cycle ( +- 0.00% ) [75.00%]
E: 3,106,381,223,355 instructions # 0.56 insns per cycle ( +- 0.01% ) [75.00%]
Understandable - we end up executing 5 insns more:
ffffffff815b90ac: 66 66 66 90 data16 data16 xchg %ax,%ax
ffffffff815b90b0: 66 66 66 90 data16 data16 xchg %ax,%ax
ffffffff815b90b4: 66 66 66 90 data16 data16 xchg %ax,%ax
ffffffff815b90b8: 66 66 66 90 data16 data16 xchg %ax,%ax
ffffffff815b90bc: 90 nop
A: 683,676,044,429 branches # 241.107 M/sec ( +- 0.01% ) [75.00%]
B: 683,670,899,595 branches # 241.293 M/sec ( +- 0.01% ) [75.00%]
C: 683,675,772,858 branches # 241.180 M/sec ( +- 0.01% ) [75.00%]
D: 683,683,533,664 branches # 241.154 M/sec ( +- 0.00% ) [75.00%]
E: 683,648,518,667 branches # 241.306 M/sec ( +- 0.01% ) [75.00%]
Lowest.
A: 43,829,535,008 branch-misses # 6.41% of all branches ( +- 0.02% ) [75.00%]
B: 43,844,118,416 branch-misses # 6.41% of all branches ( +- 0.03% ) [75.00%]
C: 43,819,871,086 branch-misses # 6.41% of all branches ( +- 0.02% ) [75.00%]
D: 43,795,107,998 branch-misses # 6.41% of all branches ( +- 0.02% ) [75.00%]
E: 43,801,985,070 branch-misses # 6.41% of all branches ( +- 0.02% ) [75.00%]
That looks like noise to me - we shouldn't be getting more branch misses
with the E: version.
A: 2,030,357 context-switches # 0.716 K/sec ( +- 0.06% ) [100.00%]
B: 2,029,313 context-switches # 0.716 K/sec ( +- 0.05% ) [100.00%]
C: 2,028,566 context-switches # 0.716 K/sec ( +- 0.06% ) [100.00%]
D: 2,028,895 context-switches # 0.716 K/sec ( +- 0.06% ) [100.00%]
E: 2,031,008 context-switches # 0.717 K/sec ( +- 0.09% ) [100.00%]
A: 52,421 migrations # 0.018 K/sec ( +- 1.13% )
B: 52,049 migrations # 0.018 K/sec ( +- 1.02% )
C: 51,365 migrations # 0.018 K/sec ( +- 0.92% )
D: 51,766 migrations # 0.018 K/sec ( +- 1.11% )
E: 53,047 migrations # 0.019 K/sec ( +- 1.08% )
A: 709.528485252 seconds time elapsed ( +- 0.02% )
B: 708.976557288 seconds time elapsed ( +- 0.04% )
C: 709.312844791 seconds time elapsed ( +- 0.02% )
D: 709.400050112 seconds time elapsed ( +- 0.01% )
E: 708.914562508 seconds time elapsed ( +- 0.06% )
Nice.
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
--
prev parent reply other threads:[~2015-04-27 14:39 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-24 2:15 [PATCH] x86_64, asm: Work around AMD SYSRET SS descriptor attribute issue Andy Lutomirski
2015-04-24 2:18 ` Andy Lutomirski
2015-04-26 12:34 ` Denys Vlasenko
2015-04-24 3:58 ` Brian Gerst
2015-04-24 9:59 ` Denys Vlasenko
2015-04-24 10:59 ` Borislav Petkov
2015-04-24 19:58 ` Borislav Petkov
2015-04-24 11:27 ` Denys Vlasenko
2015-04-24 12:00 ` Brian Gerst
2015-04-24 16:25 ` Linus Torvalds
2015-04-24 17:33 ` Brian Gerst
2015-04-24 17:41 ` Linus Torvalds
2015-04-24 17:57 ` Brian Gerst
2015-04-24 20:21 ` Andy Lutomirski
2015-04-24 20:46 ` Denys Vlasenko
2015-04-24 20:50 ` Andy Lutomirski
2015-04-24 21:45 ` H. Peter Anvin
2015-04-24 21:45 ` H. Peter Anvin
2015-04-24 21:45 ` H. Peter Anvin
2015-04-24 21:45 ` H. Peter Anvin
2015-04-24 21:45 ` H. Peter Anvin
2015-04-24 21:45 ` H. Peter Anvin
2015-04-25 2:17 ` Denys Vlasenko
2015-04-26 23:36 ` Andy Lutomirski
2015-04-24 20:53 ` Linus Torvalds
2015-04-25 21:12 ` Borislav Petkov
2015-04-26 11:22 ` perf numbers (was: Re: [PATCH] x86_64, asm: Work around AMD SYSRET SS descriptor attribute issue) Borislav Petkov
2015-04-26 23:39 ` [PATCH] x86_64, asm: Work around AMD SYSRET SS descriptor attribute issue Andy Lutomirski
2015-04-27 8:53 ` Borislav Petkov
2015-04-27 10:07 ` Denys Vlasenko
2015-04-27 10:09 ` Borislav Petkov
2015-04-27 11:35 ` Borislav Petkov
2015-04-27 12:08 ` Denys Vlasenko
2015-04-27 12:48 ` Borislav Petkov
2015-04-27 14:57 ` Linus Torvalds
2015-04-27 15:06 ` Linus Torvalds
2015-04-27 15:35 ` Borislav Petkov
2015-04-27 15:46 ` Borislav Petkov
2015-04-27 15:56 ` Andy Lutomirski
2015-04-27 16:04 ` Brian Gerst
2015-04-27 16:10 ` Denys Vlasenko
2015-04-27 16:00 ` Linus Torvalds
2015-04-27 16:40 ` Borislav Petkov
2015-04-27 18:14 ` Linus Torvalds
2015-04-27 18:38 ` Borislav Petkov
2015-04-27 18:47 ` Linus Torvalds
2015-04-27 18:53 ` Borislav Petkov
2015-04-27 19:59 ` H. Peter Anvin
2015-04-27 20:03 ` Borislav Petkov
2015-04-27 20:14 ` H. Peter Anvin
2015-04-28 15:55 ` Borislav Petkov
2015-04-28 16:28 ` Linus Torvalds
2015-04-28 16:58 ` Borislav Petkov
2015-04-28 17:16 ` Linus Torvalds
2015-04-28 18:38 ` Borislav Petkov
2015-04-30 21:39 ` H. Peter Anvin
2015-04-30 23:23 ` H. Peter Anvin
2015-05-01 9:03 ` Borislav Petkov
2015-05-03 11:51 ` Borislav Petkov
2015-04-27 19:11 ` Borislav Petkov
2015-04-27 19:21 ` Denys Vlasenko
2015-04-27 19:45 ` Borislav Petkov
2015-04-28 13:40 ` Borislav Petkov
2015-04-27 16:12 ` Denys Vlasenko
2015-04-27 18:12 ` Linus Torvalds
2015-04-27 18:47 ` Borislav Petkov
2015-04-27 14:39 ` Borislav Petkov [this message]
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