From: Arnd Bergmann <arnd@arndb•de>
To: linuxppc-dev@ozlabs•org
Cc: paulus@samba•org
Subject: Re: [PATCH 8/14] ps3: bind interrupt to cpu
Date: Thu, 25 Jan 2007 07:19:40 +0100 [thread overview]
Message-ID: <200701250719.40808.arnd@arndb.de> (raw)
In-Reply-To: <45B8188A.5070900@am.sony.com>
On Thursday 25 January 2007 03:40, Geoff Levand wrote:
> +struct ps3_bmp {
> +=A0=A0=A0=A0=A0=A0=A0struct {
> +=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0unsigned long status;
> +=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0unsigned long unused_1[3];
> +=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0unsigned long mask;
> +=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0unsigned long unused_2[3];
> +=A0=A0=A0=A0=A0=A0=A0} __attribute__ ((aligned (64)));
> +
> +=A0=A0=A0=A0=A0=A0=A0spinlock_t lock;
> +=A0=A0=A0=A0=A0=A0=A0unsigned long ipi_debug_brk_mask;
> +};
> +
> +struct ps3_private {
> +=A0=A0=A0=A0=A0=A0=A0struct ps3_bmp bmp;
> +=A0=A0=A0=A0=A0=A0=A0unsigned long node;
> +=A0=A0=A0=A0=A0=A0=A0unsigned int cpu;
> +};
This layout has some unnecessary padding in it. It turns out as:
status
unused_1
mask
unused_2
lock
/* 4 bytes pad */
ipi_debug_brk_mask
/* 48 bytes pad */
node
cpu
which you probably did not indent.
If 'status' needs to be aligned by 64 bytes, you can better express
this as
struct ps3_bmp {
struct {
unsigned long status;
unsigned long unused_1[3];
unsigned long mask;
unsigned long unused_2[3];
};
unsigned long ipi_debug_brk_mask;
spinlock_t lock;
};
struct ps3_private {
struct ps3_bmp bmp __attribute__ ((aligned (64)));
unsigned long node;
unsigned int cpu;
};
which should reduce the size of your structure from 192 bytes to 64.
Arnd <><
next prev parent reply other threads:[~2007-01-25 6:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-25 2:40 [PATCH 8/14] ps3: bind interrupt to cpu Geoff Levand
2007-01-25 3:54 ` Benjamin Herrenschmidt
2007-01-26 1:29 ` Geoff Levand
2007-01-25 6:19 ` Arnd Bergmann [this message]
2007-01-25 13:32 ` Geert Uytterhoeven
2007-01-25 13:33 ` Geert Uytterhoeven
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