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Date: Thu, 11 Jan 2018 19:34:31 +0000
From: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Olivier Galibert <galibert@pobox.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
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        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Kees Cook <keescook@chromium.org>
Subject: Re: [RFC PATCH v2 6/6] x86/entry/pti: don't switch PGD on when
 pti_disable is set
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On Thu, 11 Jan 2018 13:26:01 -0600
Josh Poimboeuf <jpoimboe@redhat.com> wrote:

> On Thu, Jan 11, 2018 at 08:19:35PM +0100, Olivier Galibert wrote:
> > Wouldn't the time taken by an easy syscall like getuid be a clear indicator?  
> 
> I think only if you had a baseline measurement to compare against.

getuid can also be cached by a smart libc. getppid() is what micro
benchmarks seem to favour.

Alan