From: Arnd Bergmann <arnd@arndb.de>
To: 김재극 <jaegeuk.kim@samsung.com>
Cc: viro@zeniv.linux.org.uk, "'Theodore Ts'o'" <tytso@mit.edu>,
gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
chur.lee@samsung.com, cm224.lee@samsung.com,
jooyoung.hwang@samsung.com
Subject: Re: [PATCH 02/16] f2fs: add on-disk layout
Date: Fri, 12 Oct 2012 21:05:08 +0000 [thread overview]
Message-ID: <1557307.tHJJu7g4Ig@wuerfel> (raw)
In-Reply-To: <000901cda2f0$7d773eb0$7865bc10$%kim@samsung.com>
On Friday 05 October 2012 20:56:44 김재극 wrote:
> +struct f2fs_nat_entry {
> + __u8 version;
> + __le32 ino;
> + __le32 block_addr;
> +} __packed;
> +
> +struct f2fs_nat_block {
> + struct f2fs_nat_entry entries[NAT_ENTRY_PER_BLOCK];
> +} __packed;
Using "__packed" on structure is rather inefficient on CPU architectures
that cannot do aligned accesses. I would suggest you remove this
attribute everywhere you can. The f2fs_nat_entry is particularly
suboptimal because it is 9 bytes long, and I'm not sure if this
can be reasonably changed to a multiple of four.
In all other cases, you should try to lay out the structures
so that each member is naturally aligned and you don't need any __packed
attributes, in particular for those that are accessed a lot.
Arnd
next prev parent reply other threads:[~2012-10-12 21:05 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-05 11:56 [PATCH 02/16] f2fs: add on-disk layout 김재극
2012-10-05 17:46 ` Martin Steigerwald
2012-10-06 18:25 ` Jaegeuk Kim
2012-10-05 17:54 ` Dan Luedtke
2012-10-05 21:09 ` Boaz Harrosh
2012-10-06 18:19 ` Jaegeuk Kim
2012-10-06 22:21 ` David Sterba
2012-10-09 5:27 ` Chul Lee
2012-10-07 6:42 ` Stefan Hajnoczi
2012-10-10 5:52 ` Jaegeuk Kim
2012-10-12 21:05 ` Arnd Bergmann [this message]
2012-10-13 11:39 ` Jaegeuk Kim
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