From: "H. Peter Anvin" <hpa@zytor.com>
To: David Sharp <dhsharp@google.com>
Cc: Vaibhav Nagarnaik <vnagarnaik@google.com>,
Ingo Molnar <mingo@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Justin Teravest <teravest@google.com>,
Laurent Chavey <chavey@google.com>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 4/6] trace: trace syscall in its handler not from ptrace handler
Date: Thu, 29 Mar 2012 15:48:34 -0700 [thread overview]
Message-ID: <4F74E6C2.8050003@zytor.com> (raw)
In-Reply-To: <CAJL_ektkRunH_FXL+VfPCZqyNvB3Ab4PNjwzF2_dORudr0a32g@mail.gmail.com>
On 03/29/2012 03:44 PM, David Sharp wrote:
>>
>> ANY increase to the fastpath is unacceptable, period.
>
> I think the last 4 ns would probably be eliminated if we could figure
> out how to call the inline function trace_sys_enter directly instead
> of through the out-of-line wrapper we had to add to work around the
> preprocessor magic.
I already told you how to do it... override the system call table entry.
There is a nice, juicy FUNCTION POINTER that we indirect through.
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
next prev parent reply other threads:[~2012-03-29 22:48 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-26 18:39 [PATCH 0/6] Enhance and speed up syscall tracing Vaibhav Nagarnaik
2012-03-26 18:39 ` [PATCH 1/6] trace: syscalls.h - cleanup and simplify SYSCALL_METADATA() Vaibhav Nagarnaik
2012-03-26 18:39 ` [PATCH 2/6] trace: add support for 32 bit compat syscalls on x86_64 Vaibhav Nagarnaik
2012-03-27 4:49 ` H. Peter Anvin
2012-03-28 21:10 ` Vaibhav Nagarnaik
2012-03-28 21:11 ` Vaibhav Nagarnaik
2012-03-28 23:00 ` Vaibhav Nagarnaik
2012-03-26 18:39 ` [PATCH 3/6] trace: Refactor ftrace syscall macros to make them more readable Vaibhav Nagarnaik
2012-03-26 18:39 ` [PATCH 4/6] trace: trace syscall in its handler not from ptrace handler Vaibhav Nagarnaik
2012-03-27 5:00 ` H. Peter Anvin
2012-03-28 18:23 ` Vaibhav Nagarnaik
2012-03-29 2:43 ` H. Peter Anvin
2012-03-29 2:59 ` Steven Rostedt
2012-03-29 3:15 ` H. Peter Anvin
2012-03-29 3:02 ` Vaibhav Nagarnaik
2012-03-29 3:16 ` H. Peter Anvin
2012-03-29 6:20 ` Ingo Molnar
2012-03-29 19:02 ` Vaibhav Nagarnaik
2012-03-29 19:12 ` H. Peter Anvin
2012-03-29 19:43 ` Vaibhav Nagarnaik
2012-03-29 20:06 ` H. Peter Anvin
2012-03-29 22:40 ` David Sharp
2012-03-29 22:44 ` H. Peter Anvin
2012-03-30 12:06 ` Frederic Weisbecker
2012-03-30 11:57 ` Frederic Weisbecker
2012-03-29 22:44 ` David Sharp
2012-03-29 22:48 ` H. Peter Anvin [this message]
2012-03-26 18:39 ` [PATCH 5/6] trace: raw_syscalls: Mark compat syscalls in the MSB of the syscall number Vaibhav Nagarnaik
2012-03-26 18:39 ` [PATCH 6/6] trace: get rid of the enabled_*_syscalls bitmaps Vaibhav Nagarnaik
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