Date: Mon, 11 May 2015 18:23:54 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Andi Kleen <andi@firstfloor.org>
Cc: eranian@google.com, linux-kernel@vger.kernel.org,
        Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH 9/9] x86, perf: Move PMU ACK after LBR read
Message-ID: <20150511162354.GA21418@twins.programming.kicks-ass.net>
References: <1431285767-27027-1-git-send-email-andi@firstfloor.org>
 <1431285767-27027-10-git-send-email-andi@firstfloor.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1431285767-27027-10-git-send-email-andi@firstfloor.org>
User-Agent: Mutt/1.5.21 (2012-12-30)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 993
Lines: 25

On Sun, May 10, 2015 at 12:22:47PM -0700, Andi Kleen wrote:
> From: Andi Kleen <ak@linux.intel.com>
> 
> With Arch Perfmon v4 the PMU ack unfreezes the LBRs. So we need to do
> the PMU ack after the LBR reading, otherwise the LBRs would be polluted by the
> PMI handler.

Hmm, we should move these last three patches before the SKL enablement
patch no, otherwise things will misbehave -- say a bisection lands in
between.

/me shuffles patches.

> This is a minimal change. In principle the ACK could be moved much later.

Right, so the more complete change would be to use the new and improved
FREEZE_ON_PMI and reenable both the LBRs and the CTRs with the
STATUS_RESET MSR, right?

Does it make sense to have a new handle_irq() routine for that?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/