From: Eric Dumazet new_inode() dirties a contended cache line to get increasing inode numbers. Solve this problem by providing to each cpu a per_cpu variable, feeded by the shared last_ino, but once every 1024 allocations. This reduce contention on the shared last_ino, and give same spreading ino numbers than before. (same wraparound after 2^32 allocations) Signed-off-by: Eric Dumazet Signed-off-by: Nick Piggin --- fs/inode.c | 42 +++++++++++++++++++++++++++++++++++------- 1 file changed, 35 insertions(+), 7 deletions(-) Index: linux-2.6/fs/inode.c =================================================================== --- linux-2.6.orig/fs/inode.c +++ linux-2.6/fs/inode.c @@ -664,6 +664,40 @@ __inode_add_to_lists(struct super_block } } +#ifdef CONFIG_SMP +/* + * Each cpu owns a range of 1024 numbers. + * 'shared_last_ino' is dirtied only once out of 1024 allocations, + * to renew the exhausted range. + * + * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW + * error if st_ino won't fit in target struct field. Use 32bit counter + * here to attempt to avoid that. + */ +static DEFINE_PER_CPU(int, last_ino); +static atomic_t shared_last_ino; + +static int last_ino_get(void) +{ + int *p = &get_cpu_var(last_ino); + int res = *p; + + if (unlikely((res & 1023) == 0)) + res = atomic_add_return(1024, &shared_last_ino) - 1024; + + *p = ++res; + put_cpu_var(last_ino); + return res; +} +#else +static int last_ino_get(void) +{ + static int last_ino; + + return ++last_ino; +} +#endif + /** * inode_add_to_lists - add a new inode to relevant lists * @sb: superblock inode belongs to @@ -700,19 +734,13 @@ EXPORT_SYMBOL_GPL(inode_add_to_lists); */ struct inode *new_inode(struct super_block *sb) { - /* - * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW - * error if st_ino won't fit in target struct field. Use 32bit counter - * here to attempt to avoid that. - */ - static atomic_t last_ino = ATOMIC_INIT(0); struct inode *inode; inode = alloc_inode(sb); if (inode) { /* XXX: init as locked for speedup */ spin_lock(&inode->i_lock); - inode->i_ino = atomic_inc_return(&last_ino); + inode->i_ino = last_ino_get(); inode->i_state = 0; __inode_add_to_lists(sb, NULL, inode); spin_unlock(&inode->i_lock); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/