[RFC PATCH 0/5] Put struct inode on a diet

From: Theodore Ts'o
Date: Thu May 21 2009 - 16:01:40 EST


These patches attempt to slim down struct inode to reduce the overhead
of storing cached inodes. A typical Linux system has hundreds of
thousands of inodes cached, if not more, so reducing the inode size is a
high leverage thing to do. For example these patches save 24 bytes, or
a little over 4% of an inode (with no debugging enabled) on an x86_64
machine. But on a system with 160,000 inodes in its inode cache, this
might mean a difference of six and half megabytes of physical memory
(once SLAB rounding issues are taken into account).

Theodore Ts'o (5):
fs: i_flags and i_state in struct inode only need to be unsigned
short
fs: Remove i_cindex from struct inode
fs: Slim down inode by only using an unsigned int for i_dnotify_mask
fs: Rearrange inode structure elements to avoid waste due to padding
Dump the inode structure (for debugging purposes only)

drivers/ieee1394/dv1394.c | 5 +-
drivers/ieee1394/ieee1394_core.h | 5 ++-
fs/Makefile | 1 +
fs/char_dev.c | 14 ++++++-
fs/inode-struct-dumper.c | 87 ++++++++++++++++++++++++++++++++++++++
include/linux/cdev.h | 2 +
include/linux/dnotify.h | 2 +-
include/linux/fs.h | 9 ++--
8 files changed, 115 insertions(+), 10 deletions(-)
create mode 100644 fs/inode-struct-dumper.c

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