Add a 'next_free' field into kioctx_table to store the next id that may be free, in order to reduce the search region when we insert kioctx into kioctx table. When we take a free slot from kioctx_table, update 'next_free' to the next slot. Also when we free one slot to kioctx_table, update 'next_free' to the new free slot if it's smaller than 'next_free'. So that we can ensure that the slots before 'next_free' are all used, and the search can start from 'next_free' to reduce the search and improve the performance.
Signed-off-by: Gu Zheng <[email protected]> --- fs/aio.c | 10 ++++++++-- 1 files changed, 8 insertions(+), 2 deletions(-) diff --git a/fs/aio.c b/fs/aio.c index 062a5f6..489fda6 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -69,6 +69,7 @@ struct aio_ring { struct kioctx_table { struct rcu_head rcu; unsigned nr; + unsigned next_free; struct kioctx *table[]; }; @@ -548,11 +549,12 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm) table = rcu_dereference(mm->ioctx_table); while (1) { - if (table) - for (i = 0; i < table->nr; i++) + if (table && table->next_free < table->nr) + for (i = table->next_free; i < table->nr; i++) if (!table->table[i]) { ctx->id = i; table->table[i] = ctx; + table->next_free = i + 1; rcu_read_unlock(); spin_unlock(&mm->ioctx_lock); @@ -579,8 +581,10 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm) old = rcu_dereference(mm->ioctx_table); if (!old) { + table->next_free = 0; rcu_assign_pointer(mm->ioctx_table, table); } else if (table->nr > old->nr) { + table->next_free = old->nr; memcpy(table->table, old->table, old->nr * sizeof(struct kioctx *)); @@ -716,6 +720,8 @@ static void kill_ioctx(struct mm_struct *mm, struct kioctx *ctx) WARN_ON(ctx != table->table[ctx->id]); table->table[ctx->id] = NULL; + if (ctx->id < table->next_free) + table->next_free = ctx->id; rcu_read_unlock(); spin_unlock(&mm->ioctx_lock); -- 1.7.7 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
