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From: David Miller <davem@davemloft.net>
To: mathieu.desnoyers@efficios.com
Cc: linux-kernel@vger.kernel.org, rostedt@goodmis.org,
	fweisbec@gmail.com, mingo@elte.hu, richm@oldelvet.org.uk,
	ben@decadent.org.uk, sparclinux@vger.kernel.org
Subject: Re: [patch 3/3] tracepoints: use __u64_aligned/U64_ALIGN()
Date: Fri, 21 Jan 2011 16:05:16 -0800 (PST)	[thread overview]
Message-ID: <20110121.160516.256850550.davem@davemloft.net> (raw)
In-Reply-To: <20110121203643.046218322@efficios.com>

From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Fri, 21 Jan 2011 15:36:33 -0500

> commit 7e066fb870fcd1025ec3ba7bbde5d541094f4ce1 added the aligned(32) type and
> variable attribute to the tracepoint structures to deal with gcc happily
> aligning statically defined structures on 32-byte multiples.
> 
> Working on issues within Ftrace, we came up with __64_aligned, which deals with
> this issue more elegantly by forcing an 8-byte alignment to both the type
> declaration and variable definition.
> 
> This therefore saves space, bringing down the size of struct tracepoint from 64
> bytes to 38 on 64-bit architectures.
> 
> Updating:
> - The type attribute (for iteration over the struct tracepoint array)
> - Added the variable attribute to the extern definition (needed to force gcc to
>   consider this alignment for the following definition)
> - The definition variable attribute (to force gcc to this specific alignment for
>   the static definitions)
> - The linker script (8-byte alignment can now replace the previous 32-byte
>   alignment for the custom tracepoint section)
> 
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Acked-by: David S. Miller <davem@davemloft.net>

  reply	other threads:[~2011-01-22  0:04 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-01-21 20:36 [patch 0/3] Fix alignment of custom sections made from structures (v3) Mathieu Desnoyers
2011-01-21 20:36 ` [patch 1/3] introduce __u64_aligned and U64_ALIGN() for structure alignment in custom sections (v3) Mathieu Desnoyers
2011-01-22  0:05   ` David Miller
2011-01-22 17:11     ` Mathieu Desnoyers
2011-01-22 17:43       ` Steven Rostedt
2011-01-25 23:34         ` Mathieu Desnoyers
2011-01-26  0:25           ` Steven Rostedt
2011-01-26  7:12   ` [tip:perf/core] Introduce __u64_aligned and U64_ALIGN() for structure alignment in custom sections tip-bot for Mathieu Desnoyers
2011-01-21 20:36 ` [patch 2/3] tracing: fix sparc64 alignment crash with __u64_aligned/U64_ALIGN() Mathieu Desnoyers
2011-01-22  0:05   ` David Miller
2011-01-22 17:15     ` Mathieu Desnoyers
2011-01-26  7:13   ` [tip:perf/core] tracing: Fix " tip-bot for Mathieu Desnoyers
2011-01-21 20:36 ` [patch 3/3] tracepoints: use __u64_aligned/U64_ALIGN() Mathieu Desnoyers
2011-01-22  0:05   ` David Miller [this message]
2011-01-26  7:13   ` [tip:perf/core] tracepoints: Use __u64_aligned/U64_ALIGN() tip-bot for Mathieu Desnoyers
2011-01-26  4:04 [PATCH 0/3] [GIT PULL][v2.6.38] tracing: fix unaligned event arrays Steven Rostedt
2011-01-26  4:05 ` [PATCH 3/3] tracepoints: Use __u64_aligned/U64_ALIGN() Steven Rostedt
2011-01-27 18:19   ` Jiri Olsa
2011-01-27 18:22     ` Steven Rostedt
2011-01-27 19:09       ` Ingo Molnar
2011-01-27 19:11         ` Steven Rostedt

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