From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from hr2.samba.org (hr2.samba.org [144.76.82.148]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3rHwn46w3HzDqPD for ; Mon, 30 May 2016 09:24:08 +1000 (AEST) Date: Mon, 30 May 2016 09:23:40 +1000 From: Anton Blanchard To: Michael Neuling Cc: Anton Blanchard , mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, aneesh.kumar@linux.vnet.ibm.com, acsawdey@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH 2/3] powerpc: Avoid load hit store in setup_sigcontext() Message-ID: <20160530092340.4244948c@kryten> In-Reply-To: <1464563663.27056.74.camel@neuling.org> References: <1464523432-12605-1-git-send-email-anton@ozlabs.org> <1464523432-12605-2-git-send-email-anton@ozlabs.org> <1464563663.27056.74.camel@neuling.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi, > On Sun, 2016-05-29 at 22:03 +1000, Anton Blanchard wrote: > > From: Anton Blanchard > > > > In setup_sigcontext(), we set current->thread.vrsave then use it > > straight after. Since current is hidden from the compiler via inline > > assembly, it cannot optimise this and we end up with a load hit > > store. > > Is setup_sigcontext() really a fast path we need to optimise? setup_sigcontext() is called for every signal we deliver. I'd like userspace to use less signals, but we still stumble across workloads with quite heavy use of them. Anton