Subject: Re: [PATCH 02/11] mm: call import_iovec() instead of rw_copy_check_uvector() in process_vm_rw()

From: Christoph Hellwig <[email-masked]>
Date: Mon, 21 Sep 2020 18:12:24 +0200

On Mon, Sep 21, 2020 at 04:29:37PM +0100, Al Viro wrote:
> On Mon, Sep 21, 2020 at 03:21:35PM +0000, David Laight wrote:
> 
> > You really don't want to be looping through the array twice.
> 
> Profiles, please.

Given that the iov array should be cache hot I'd be surprised to
see a huge difference.