From mboxrd@z Thu Jan  1 00:00:00 1970
From: "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH] x86: Add an explicit barrier() to clflushopt()
Date: Thu, 7 Jan 2016 13:05:35 -0800
Message-ID: <568ED31F.1090004@zytor.com>
References: <1445248735-11915-1-git-send-email-chris@chris-wilson.co.uk>
 <20160107101652.GF652@nuc-i3427.alporthouse.com>
 <CALCETrU8otVfBe0+N-E0sc=j2L79qh7gqte7QSVb_YzGbJYNCA@mail.gmail.com>
 <20160107194413.GA25144@nuc-i3427.alporthouse.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=windows-1252
Content-Transfer-Encoding: 7bit
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <20160107194413.GA25144@nuc-i3427.alporthouse.com>
Sender: linux-kernel-owner@vger.kernel.org
To: Chris Wilson <chris@chris-wilson.co.uk>, Andy Lutomirski <luto@amacapital.net>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Ross Zwisler <ross.zwisler@linux.intel.com>, "H . Peter Anvin" <hpa@linux.intel.com>, Borislav Petkov <bp@alien8.de>, Brian Gerst <brgerst@gmail.com>, Denys Vlasenko <dvlasenk@redhat.com>, Linus Torvalds <torvalds@linux-foundation.org>, Thomas Gleixner <tglx@linutronix.de>, Imre Deak <imre.deak@intel.com>, Daniel Vetter <daniel.vetter@ffwll.ch>, DRI <dri-devel@lists.freedesktop.org>
List-Id: dri-devel@lists.freedesktop.org

On 01/07/16 11:44, Chris Wilson wrote:
> 
> Now I feel silly. Looking at the .s, there is no difference with the
> addition of the barrier to clflush_cache_range(). And sure enough
> letting the test run for longer, we see a failure. I fell for a placebo.
> 
> The failing assertion is always on the last cacheline and is always one
> value behind. Oh well, back to wondering where we miss the flush.
> -Chris
> 

Could you include the assembly here?

	-hpa