From: Jason Baron <jbaron@redhat.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Paul Mackerras <paulus@samba.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Steven Rostedt <rostedt@goodmis.org>,
a.p.zijlstra@chello.nl, mathieu.desnoyers@efficios.com,
davem@davemloft.net, ddaney.cavm@gmail.com,
akpm@linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 00/10] jump label: introduce very_[un]likely + cleanups + docs
Date: Thu, 23 Feb 2012 21:42:39 -0500 [thread overview]
Message-ID: <20120224024238.GB3777@redhat.com> (raw)
In-Reply-To: <20120223223348.GA25513@elte.hu>
On Thu, Feb 23, 2012 at 11:33:48PM +0100, Ingo Molnar wrote:
>
> Before:
>
> ffffffff810441f0 <sys_getppid>:
> ffffffff810441f0: 8b 05 8a 52 d8 00 mov 0xd8528a(%rip),%eax # ffffffff81dc9480 <key>
> ffffffff810441f6: 55 push %rbp
> ffffffff810441f7: 48 89 e5 mov %rsp,%rbp
> ffffffff810441fa: 85 c0 test %eax,%eax
> ffffffff810441fc: 75 27 jne ffffffff81044225 <sys_getppid+0x35>
> ffffffff810441fe: 65 48 8b 04 25 c0 b6 mov %gs:0xb6c0,%rax
> ffffffff81044205: 00 00
> ffffffff81044207: 48 8b 80 80 02 00 00 mov 0x280(%rax),%rax
> ffffffff8104420e: 48 8b 80 b0 02 00 00 mov 0x2b0(%rax),%rax
> ffffffff81044215: 48 8b b8 e8 02 00 00 mov 0x2e8(%rax),%rdi
> ffffffff8104421c: e8 2f da 00 00 callq ffffffff81051c50 <pid_vnr>
> ffffffff81044221: 5d pop %rbp
> ffffffff81044222: 48 98 cltq
> ffffffff81044224: c3 retq
> ffffffff81044225: 48 c7 c7 13 53 98 81 mov $0xffffffff81985313,%rdi
> ffffffff8104422c: 31 c0 xor %eax,%eax
> ffffffff8104422e: e8 60 0f 6d 00 callq ffffffff81715193 <printk>
> ffffffff81044233: eb c9 jmp ffffffff810441fe <sys_getppid+0xe>
> ffffffff81044235: 66 66 2e 0f 1f 84 00 data32 nopw %cs:0x0(%rax,%rax,1)
> ffffffff8104423c: 00 00 00 00
>
> After:
>
> ffffffff81044290 <sys_getppid>:
> ffffffff81044290: 55 push %rbp
> ffffffff81044291: 48 89 e5 mov %rsp,%rbp
> ffffffff81044294: e9 00 00 00 00 jmpq ffffffff81044299 <sys_getppid+0x9>
> ffffffff81044299: 65 48 8b 04 25 c0 b6 mov %gs:0xb6c0,%rax
> ffffffff810442a0: 00 00
> ffffffff810442a2: 48 8b 80 80 02 00 00 mov 0x280(%rax),%rax
> ffffffff810442a9: 48 8b 80 b0 02 00 00 mov 0x2b0(%rax),%rax
> ffffffff810442b0: 48 8b b8 e8 02 00 00 mov 0x2e8(%rax),%rdi
> ffffffff810442b7: e8 f4 d9 00 00 callq ffffffff81051cb0 <pid_vnr>
> ffffffff810442bc: 5d pop %rbp
> ffffffff810442bd: 48 98 cltq
> ffffffff810442bf: c3 retq
> ffffffff810442c0: 48 c7 c7 e3 54 98 81 mov $0xffffffff819854e3,%rdi
> ffffffff810442c7: 31 c0 xor %eax,%eax
> ffffffff810442c9: e8 71 13 6d 00 callq ffffffff8171563f <printk>
> ffffffff810442ce: eb c9 jmp ffffffff81044299 <sys_getppid+0x9>
>
> The prior slowpath test:
>
> ffffffff810441fa: 85 c0 test %eax,%eax
> ffffffff810441fc: 75 27 jne ffffffff81044225 <sys_getppid+0x35>
>
> became even faster and turned into a single NOP, making the
> fastpath even faster.
>
and the: mov 0xd8528a(%rip),%eax # ffffffff81dc9480 <key>
is no longer present.
Thanks,
-Jason
next prev parent reply other threads:[~2012-02-24 2:42 UTC|newest]
Thread overview: 84+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-21 20:02 [PATCH 00/10] jump label: introduce very_[un]likely + cleanups + docs Jason Baron
2012-02-21 20:02 ` [PATCH 01/10] jump label: Add a WARN() if jump label key count goes negative Jason Baron
2012-02-29 10:13 ` [tip:perf/core] " tip-bot for Jason Baron
2012-02-21 20:02 ` [PATCH 02/10] jump label: fix compiler warning Jason Baron
2012-02-29 10:14 ` [tip:perf/core] jump label: Fix " tip-bot for Jason Baron
2012-02-21 20:03 ` [PATCH 03/10] jump label: introduce very_unlikely() Jason Baron
2012-02-21 20:03 ` [PATCH 04/10] jump label: introduce very_likely() Jason Baron
2012-02-21 20:03 ` [PATCH 05/10] perf: update to use 'very_unlikely()' Jason Baron
2012-02-21 20:03 ` [PATCH 06/10] tracepoints: update to use very_unlikely() Jason Baron
2012-02-21 20:03 ` [PATCH 07/10] sched: update to use very_[un]likely() Jason Baron
2012-02-21 20:03 ` [PATCH 08/10] kvm: update to use very_unlikely() Jason Baron
2012-02-21 20:03 ` [PATCH 09/10] net: " Jason Baron
2012-02-21 20:03 ` [PATCH 10/10] jump label: Add docs better explaining the whole jump label mechanism Jason Baron
2012-02-29 10:15 ` [tip:perf/core] static keys: Add docs better explaining the whole 'struct static_key' mechanism tip-bot for Jason Baron
2012-02-21 20:09 ` [PATCH 00/10] jump label: introduce very_[un]likely + cleanups + docs H. Peter Anvin
2012-02-21 20:20 ` Jason Baron
2012-02-21 20:39 ` Steven Rostedt
2012-02-21 21:10 ` H. Peter Anvin
2012-02-21 21:16 ` Mathieu Desnoyers
2012-02-21 21:11 ` Mathieu Desnoyers
2012-02-22 7:32 ` Ingo Molnar
2012-02-22 7:53 ` Ingo Molnar
2012-02-22 8:01 ` H. Peter Anvin
2012-02-22 8:18 ` Ingo Molnar
2012-02-22 8:58 ` [PATCH] static keys: Introduce 'struct static_key', very_[un]likely(), static_key_slow_[inc|dec]() Ingo Molnar
2012-02-29 10:16 ` [tip:perf/core] static keys: Introduce 'struct static_key', static_key_true()/false() and static_key_slow_[inc|dec]() tip-bot for Ingo Molnar
2012-02-22 9:03 ` [PATCH] jump labels: Explain the .config option better Ingo Molnar
2012-02-22 15:08 ` [PATCH 00/10] jump label: introduce very_[un]likely + cleanups + docs H. Peter Anvin
2012-02-22 15:51 ` Ingo Molnar
2012-02-22 21:33 ` Paul Mackerras
2012-02-23 10:02 ` Ingo Molnar
2012-02-23 16:21 ` Jason Baron
2012-02-23 17:10 ` H. Peter Anvin
2012-02-24 9:11 ` Ingo Molnar
2012-02-23 17:18 ` Linus Torvalds
2012-02-23 22:33 ` Ingo Molnar
2012-02-23 22:39 ` Ingo Molnar
2012-02-23 22:44 ` Steven Rostedt
2012-02-23 23:18 ` Mathieu Desnoyers
2012-02-24 2:25 ` Jason Baron
2012-02-24 9:08 ` Ingo Molnar
2012-02-24 15:35 ` Jason Baron
2012-02-27 7:40 ` Ingo Molnar
2012-02-24 15:51 ` Mathieu Desnoyers
2012-02-24 16:06 ` Steven Rostedt
2012-02-24 7:52 ` static keys: Introduce 'struct static_key', static_key_true()/false() and static_key_slow_[inc|dec]() Ingo Molnar
2012-02-24 7:59 ` [PATCH] " Ingo Molnar
2012-02-24 7:54 ` [PATCH] static keys: Add docs better explaining the whole 'struct static_key' mechanism Ingo Molnar
2012-02-23 22:45 ` [PATCH 00/10] jump label: introduce very_[un]likely + cleanups + docs Linus Torvalds
2012-02-24 8:04 ` Ingo Molnar
2012-02-24 2:42 ` Jason Baron [this message]
2012-02-21 20:21 ` Steven Rostedt
2012-02-21 21:11 ` H. Peter Anvin
2012-02-22 6:50 ` Ingo Molnar
2012-02-22 7:03 ` H. Peter Anvin
2012-02-22 7:25 ` Ingo Molnar
2012-02-22 7:35 ` H. Peter Anvin
2012-02-22 7:48 ` Ingo Molnar
2012-02-22 7:55 ` H. Peter Anvin
2012-02-22 8:06 ` Ingo Molnar
2012-02-22 13:22 ` Steven Rostedt
2012-02-22 13:34 ` Ingo Molnar
2012-02-22 13:54 ` Steven Rostedt
2012-02-22 14:20 ` Mathieu Desnoyers
2012-02-22 14:36 ` Steven Rostedt
2012-02-22 14:56 ` Ingo Molnar
2012-02-22 15:11 ` H. Peter Anvin
2012-02-22 15:11 ` Peter Zijlstra
2012-02-22 15:47 ` Ingo Molnar
2012-02-22 15:12 ` Steven Rostedt
2012-02-22 15:15 ` H. Peter Anvin
2012-02-22 15:19 ` H. Peter Anvin
2012-02-22 15:42 ` Jason Baron
2012-02-22 15:54 ` Steven Rostedt
2012-02-22 15:56 ` Jason Baron
2012-02-22 16:08 ` Steven Rostedt
2012-02-22 15:19 ` Jason Baron
2012-02-22 15:40 ` H. Peter Anvin
2012-02-22 15:13 ` Peter Zijlstra
2012-02-22 15:32 ` Peter Zijlstra
2012-02-22 17:14 ` Richard Henderson
2012-02-22 18:28 ` H. Peter Anvin
2012-02-22 18:58 ` Jason Baron
2012-02-22 19:10 ` H. Peter Anvin
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