14 Jan, 2009
1 commit
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System calls with an unsigned long long argument can't be converted with
the standard wrappers since that would include a cast to long, which in
turn means that we would lose the upper 32 bit on 32 bit architectures.
Also semctl can't use the standard wrapper since it has a 'union'
parameter.So we handle them as special case and add some extra wrappers instead.
Signed-off-by: Heiko Carstens
01 Jan, 2009
1 commit
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struct dentry is one of the most critical structures in the kernel. So it's
sad to see it going neglected.With CONFIG_PROFILING turned on (which is probably the common case at least
for distros and kernel developers), sizeof(struct dcache) == 208 here
(64-bit). This gives 19 objects per slab.I packed d_mounted into a hole, and took another 4 bytes off the inline
name length to take the padding out from the end of the structure. This
shinks it to 200 bytes. I could have gone the other way and increased the
length to 40, but I'm aiming for a magic number, read on...I then got rid of the d_cookie pointer. This shrinks it to 192 bytes. Rant:
why was this ever a good idea? The cookie system should increase its hash
size or use a tree or something if lookups are a problem. Also the "fast
dcookie lookups" in oprofile should be moved into the dcookie code -- how
can oprofile possibly care about the dcookie_mutex? It gets dropped after
get_dcookie() returns so it can't be providing any sort of protection.At 192 bytes, 21 objects fit into a 4K page, saving about 3MB on my system
with ~140 000 entries allocated. 192 is also a multiple of 64, so we get
nice cacheline alignment on 64 and 32 byte line systems -- any given dentry
will now require 3 cachelines to touch all fields wheras previously it
would require 4.I know the inline name size was chosen quite carefully, however with the
reduction in cacheline footprint, it should actually be just about as fast
to do a name lookup for a 36 character name as it was before the patch (and
faster for other sizes). The memory footprint savings for names which are
36 bytes long should more than make up for the memory cost for
33-36 byte names.Performance is a feature...
Signed-off-by: Al Viro
15 Feb, 2008
2 commits
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d_path() is used on a pair. Lets use a struct path to
reflect this.[akpm@linux-foundation.org: fix build in mm/memory.c]
Signed-off-by: Jan Blunck
Acked-by: Bryan Wu
Acked-by: Christoph Hellwig
Cc: Al Viro
Cc: "J. Bruce Fields"
Cc: Neil Brown
Cc: Michael Halcrow
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
get_dcookie() is always called with a dentry and a vfsmount from a struct
path. Make get_dcookie() take it directly as an argument.[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Jan Blunck
Acked-by: Christoph Hellwig
Cc: Al Viro
Cc: "J. Bruce Fields"
Cc: Neil Brown
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
