RE: [RFC,iov_iter v2 3/8] iov_iter: add copyin_iovec helper

[David Laight]

From: Joe Damato
> Sent: 13 June 2022 15:43
...
> > The additional costs of all the 'iovec' types is bad enough
> > already.
> 
> Do you have data you can share on this?

I was thinking of the performance drop noticed when (IIRC)
reads/writes of /dev/null were pushed through the iovec code.

But there is a lot of overhead code for the usual case
of a single user buffer being copied.

	David

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