From: "H. Peter Anvin" <hpa@zytor.com>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Jason Baron <jbaron@redhat.com>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
Koki Sanagi <sanagi.koki@jp.fujitsu.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@elte.hu>,
Frederic Weisbecker <fweisbec@gmail.com>,
nhorman@tuxdriver.com, scott.a.mcmillan@intel.com,
laijs@cn.fujitsu.com, LKML <linux-kernel@vger.kernel.org>,
eric.dumazet@gmail.com, kaneshige.kenji@jp.fujitsu.com,
David Miller <davem@davemloft.net>,
izumi.taku@jp.fujitsu.com, kosaki.motohiro@jp.fujitsu.com,
Heiko Carstens <heiko.carstens@de.ibm.com>,
"Luck, Tony" <tony.luck@intel.com>
Subject: Re: [PATCH] tracing: Cleanup the convoluted softirq tracepoints
Date: Mon, 25 Oct 2010 15:19:35 -0700 [thread overview]
Message-ID: <4CC60277.7050700@zytor.com> (raw)
In-Reply-To: <4CC600DA.2000609@zytor.com>
On 10/25/2010 03:12 PM, H. Peter Anvin wrote:
>
> On 64 bits, use P6_NOP5; it seems to not suck on any platform.
>
> On 32 bits, 3E 8D 74 26 00 (i.e. DS: + GENERIC_NOP4) seems to at least
> do okay.
>
> I can't say these are the *best* (in fact, they are guaranteed not the
> best on some significant number of chips), but they haven't sucked on
> any chips I have been able to measure -- and are way faster than JMP.
>
This is pure conjecture, I have not measured it, but I suspect in fact
that we could just change the composite nops in nops.h to use a 3E
prefix instead of a separate 90 nop. Some platforms will take a penalty
on the prefix, but that would be balanced against handling two instructions.
The P5 core and others of the same generation might suffer, as it might
have been able to do U+V pipe pairing on two instructions which it
wouldn't for prefixes.
-hpa
next prev parent reply other threads:[~2010-10-25 22:20 UTC|newest]
Thread overview: 93+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-23 9:41 [PATCH v4 0/5] netdev: show a process of packets Koki Sanagi
2010-08-23 9:42 ` [PATCH v4 1/5] irq: add tracepoint to softirq_raise Koki Sanagi
2010-09-03 15:29 ` Frederic Weisbecker
2010-09-03 15:39 ` Steven Rostedt
2010-09-03 15:42 ` Frederic Weisbecker
2010-09-03 15:43 ` Steven Rostedt
2010-09-03 15:50 ` Frederic Weisbecker
2010-09-06 1:46 ` Koki Sanagi
2010-09-08 8:33 ` [tip:perf/core] irq: Add " tip-bot for Lai Jiangshan
2010-09-08 11:25 ` [sparc build bug] " Ingo Molnar
2010-09-08 12:26 ` [PATCH] irq: Fix circular headers dependency Frederic Weisbecker
2010-09-09 19:54 ` [tip:perf/core] " tip-bot for Frederic Weisbecker
2010-10-18 9:44 ` [sparc build bug] Re: [tip:perf/core] irq: Add tracepoint to softirq_raise Peter Zijlstra
2010-10-18 10:11 ` Peter Zijlstra
2010-10-18 10:26 ` Heiko Carstens
2010-10-18 10:48 ` Peter Zijlstra
2010-10-19 10:58 ` Koki Sanagi
2010-10-19 11:25 ` Peter Zijlstra
2010-10-19 13:00 ` [PATCH] tracing: Cleanup the convoluted softirq tracepoints Thomas Gleixner
2010-10-19 13:08 ` Peter Zijlstra
2010-10-19 13:22 ` Mathieu Desnoyers
2010-10-19 13:41 ` Thomas Gleixner
2010-10-19 13:54 ` Steven Rostedt
2010-10-19 14:07 ` Thomas Gleixner
2010-10-19 14:28 ` Mathieu Desnoyers
2010-10-19 19:49 ` Thomas Gleixner
2010-10-19 20:55 ` Steven Rostedt
2010-10-19 21:07 ` Thomas Gleixner
2010-10-19 21:23 ` Steven Rostedt
2010-10-19 21:48 ` H. Peter Anvin
2010-10-19 22:23 ` Steven Rostedt
2010-10-19 22:26 ` H. Peter Anvin
2010-10-19 22:27 ` Peter Zijlstra
2010-10-19 23:39 ` H. Peter Anvin
2010-10-19 23:45 ` Steven Rostedt
2010-10-20 0:43 ` Jason Baron
2010-10-19 22:41 ` Mathieu Desnoyers
2010-10-19 22:49 ` H. Peter Anvin
2010-10-19 23:05 ` Steven Rostedt
2010-10-19 23:09 ` H. Peter Anvin
2010-10-20 15:27 ` Jason Baron
2010-10-20 15:41 ` Mathieu Desnoyers
2010-10-25 21:54 ` H. Peter Anvin
2010-10-25 22:01 ` Mathieu Desnoyers
2010-10-25 22:12 ` H. Peter Anvin
2010-10-25 22:19 ` H. Peter Anvin [this message]
2010-10-25 22:55 ` Mathieu Desnoyers
2010-10-26 0:39 ` Steven Rostedt
2010-10-26 1:14 ` Mathieu Desnoyers
2010-10-19 22:04 ` Thomas Gleixner
2010-10-19 22:33 ` Steven Rostedt
2010-10-21 16:18 ` Thomas Gleixner
2010-10-21 17:05 ` Steven Rostedt
2010-10-21 19:56 ` Thomas Gleixner
2010-10-25 22:31 ` H. Peter Anvin
2010-10-19 21:45 ` Thomas Gleixner
2010-10-19 22:14 ` Steven Rostedt
2010-10-19 21:16 ` David Daney
2010-10-19 21:32 ` Jason Baron
2010-10-19 21:38 ` David Daney
2010-10-19 21:47 ` Steven Rostedt
2010-10-19 21:28 ` Jason Baron
2010-10-19 21:55 ` Thomas Gleixner
2010-10-19 22:17 ` Thomas Gleixner
2010-10-20 1:36 ` Steven Rostedt
2010-10-20 1:52 ` Jason Baron
2010-10-25 22:32 ` H. Peter Anvin
2010-10-19 22:38 ` Jason Baron
2010-10-19 22:44 ` H. Peter Anvin
2010-10-19 22:56 ` Steven Rostedt
2010-10-19 22:57 ` H. Peter Anvin
2010-10-19 14:46 ` Steven Rostedt
2010-10-19 14:00 ` Mathieu Desnoyers
2010-10-21 14:52 ` [tip:perf/core] " tip-bot for Thomas Gleixner
2010-08-23 9:43 ` [PATCH v4 2/5] napi: convert trace_napi_poll to TRACE_EVENT Koki Sanagi
2010-08-24 3:52 ` David Miller
2010-09-08 8:34 ` [tip:perf/core] napi: Convert " tip-bot for Neil Horman
2010-08-23 9:45 ` [PATCH v4 3/5] netdev: add tracepoints to netdev layer Koki Sanagi
2010-08-24 3:53 ` David Miller
2010-09-08 8:34 ` [tip:perf/core] netdev: Add " tip-bot for Koki Sanagi
2010-08-23 9:46 ` [PATCH v4 4/5] skb: add tracepoints to freeing skb Koki Sanagi
2010-08-24 3:53 ` David Miller
2010-09-08 8:35 ` [tip:perf/core] skb: Add " tip-bot for Koki Sanagi
2010-08-23 9:47 ` [PATCH v4 5/5] perf:add a script shows a process of packet Koki Sanagi
2010-08-24 3:53 ` David Miller
2010-09-07 16:57 ` Frederic Weisbecker
2010-09-08 8:35 ` [tip:perf/core] perf: Add a script to show packets processing tip-bot for Koki Sanagi
2010-08-30 23:50 ` [PATCH v4 0/5] netdev: show a process of packets Steven Rostedt
2010-09-03 2:10 ` Koki Sanagi
2010-09-03 2:17 ` David Miller
2010-09-03 2:55 ` Koki Sanagi
2010-09-03 4:46 ` Frederic Weisbecker
2010-09-03 5:12 ` Koki Sanagi
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