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SubjectRe: [RFC PATCH] add lookup hint for network file systems
On Fri, 23 Jun 2006 21:04:30 +0900 (JST)
ASANO Masahiro <masano@tnes.nec.co.jp> wrote:

> Hi,
>
> I'm trying to speeding up mkdir(2) for network file systems.
> A typical mkdir(2) calls two inode_operations: lookup and mkdir.
> The lookup operation would fail with ENOENT in common case. I think
> it is unnecessary because the subsequent mkdir operation can check it.
> In case of creat(2), lookup operation is called with the LOOKUP_CREATE
> flag, so individual filesystem can omit real lookup. e.g. nfs_lookup().
>
> Here is a sample patch which uses LOOKUP_CREATE and O_EXCL on mkdir,
> symlink and mknod. This uses the gadget for creat(2).
>
> And here is the result of a benchmark on NFSv3.
> mkdir(2) 10,000 times:
> original 50.5 sec
> patched 29.0 sec
>
> Signed-off-by: ASANO Masahiro <masano@tnes.nec.co.jp>
>
> ---
>
> fs/namei.c | 2 ++
> 1 files changed, 2 insertions(+), 0 deletions(-)
>
> 5273ee304b4dc1096432dc3f3aa9183e20afab1d
> diff --git a/fs/namei.c b/fs/namei.c
> index 184fe4a..209867d 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -1759,6 +1759,8 @@ struct dentry *lookup_create(struct name
> if (nd->last_type != LAST_NORM)
> goto fail;
> nd->flags &= ~LOOKUP_PARENT;
> + nd->flags |= LOOKUP_CREATE;
> + nd->intent.open.flags = O_EXCL;
>
> /*
> * Do the final lookup.

whoa. Big patch ;)

I'll save it up for when Trond returns, thanks.
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