linux-kernel - Re: [PATCH 1/3] perf: Fix timechart header handling

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Date:	Sun, 6 Dec 2009 13:13:53 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
Cc:	Arjan van de Ven <arjan@...radead.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] perf: Fix timechart header handling


* OGAWA Hirofumi <hirofumi@...l.parknet.co.jp> wrote:

> Ingo Molnar <mingo@...e.hu> writes:
> 
> > * OGAWA Hirofumi <hirofumi@...l.parknet.co.jp> wrote:
> >
> >> Hi,
> >> 
> >> Update "struct trace_entry" to match with current one. And remove
> >> "size" field from it.
> >> 
> >> If it has "size", it become cause of alignment mismatch of structure
> >> with kernel.
> >> 
> >> Signed-off-by: OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
> >> ---
> >> 
> >>  tools/perf/builtin-timechart.c |   12 ++++++++----
> >>  1 file changed, 8 insertions(+), 4 deletions(-)
> >
> > Just curious, have you tested timechart functionality after having done 
> > this change - does it still work fine for you?
> 
> Yes. Rather, it doesn't work without this. (Without patch, it provide
> svg output, but it doesn't provide correct sched state. And this issue
> is only 64bit arch.)
> 
> E.g. The following has difference (perf timechart doesn't has hole).
> 
> In kernel,
> 
> struct ftrace_raw_sched_switch {
> 	struct trace_entry         ent;                  /*     0    12 */
> 	char                       prev_comm[16];        /*    12    16 */
> 	pid_t                      prev_pid;             /*    28     4 */
> 	int                        prev_prio;            /*    32     4 */
> 
> 	/* XXX 4 bytes hole, try to pack */
> 
> 	long int                   prev_state;           /*    40     8 */
> 	char                       next_comm[16];        /*    48    16 */
> 	/* --- cacheline 1 boundary (64 bytes) --- */
> 	pid_t                      next_pid;             /*    64     4 */
> 	int                        next_prio;            /*    68     4 */
> 	char                       __data[0];            /*    72     0 */
> 
> 	/* size: 72, cachelines: 2, members: 9 */
> 	/* sum members: 68, holes: 1, sum holes: 4 */
> 	/* last cacheline: 8 bytes */
> };
> 
> In perl timechart, [Note, struct trace_entry is including "u32 size"]
> 
> struct sched_switch {
> 	struct trace_entry         te;                   /*     0    16 */
> 	char                       prev_comm[16];        /*    16    16 */
> 	int                        prev_pid;             /*    32     4 */
> 	int                        prev_prio;            /*    36     4 */
> 	long int                   prev_state;           /*    40     8 */
> 	char                       next_comm[16];        /*    48    16 */
> 	/* --- cacheline 1 boundary (64 bytes) --- */
> 	int                        next_pid;             /*    64     4 */
> 	int                        next_prio;            /*    68     4 */
> 
> 	/* size: 72, cachelines: 2, members: 8 */
> 	/* last cacheline: 8 bytes */
> };
> 

ok - thanks for the confirmation!

	Ingo
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