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From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH][CFT] Saner error handling in skb_copy_datagram_iter()
 et.al.
Date: Fri, 17 Feb 2017 10:54:20 -0500 (EST)
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From: Al Viro <viro@ZenIV.linux.org.uk>
Date: Tue, 14 Feb 2017 01:33:06 +0000

> OK...  Remaining interesting question is whether it adds a noticable
> overhead.  Could somebody try it on assorted benchmarks and see if
> it slows the things down?  The patch in question follows:

That's about a 40 byte copy onto the stack for each invocation of this
thing.  You can benchmark all you want, but it's clear that this is
non-trivial amount of work and will take some operations from fitting
in the cache to not doing so for sure.