From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 0A64FB6F7C for ; Thu, 17 Mar 2011 07:34:45 +1100 (EST) Subject: Re: [PATCH] powerpc: perf: Handle events that raise an exception without overflowing From: Benjamin Herrenschmidt To: Ingo Molnar In-Reply-To: <20110316125053.GA7387@elte.hu> References: <20110309143842.6c22845e@kryten> <20110316125053.GA7387@elte.hu> Content-Type: text/plain; charset="UTF-8" Date: Thu, 17 Mar 2011 07:34:26 +1100 Message-ID: <1300307666.22236.1179.camel@pasglop> Mime-Version: 1.0 Cc: linuxppc-dev@lists.ozlabs.org, paulus@samba.org, Anton Blanchard , acme@ghostprotocols.net, a.p.zijlstra@chello.nl List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 2011-03-16 at 13:50 +0100, Ingo Molnar wrote: > * Anton Blanchard wrote: > > > > > Events on POWER7 can roll back if a speculative event doesn't > > eventually complete. Unfortunately in some rare cases they will > > raise a performance monitor exception. We need to catch this to > > ensure we reset the PMC. In all cases the PMC will be 256 or less > > cycles from overflow. > > > > Signed-off-by: Anton Blanchard > > Cc: stable@kernel.org > > --- > > > > I would prefer not to add the PVR check, but I think we want to limit > > this workaround to POWER7. Would a cpu feature be preferable? > > There was no objection from the PowerPC folks so i'll send this fix Linuswards, ok? Ah yes. Ack. Cheers, Ben.