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)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3tJ2MY5Jn4zDsxW for ; Tue, 15 Nov 2016 20:36:25 +1100 (AEDT) Message-ID: <1479202544.2608.56.camel@kernel.crashing.org> Subject: Re: [PATCH v3 11/11] powerpc: rewrite local_t using soft_irq From: Benjamin Herrenschmidt To: Gabriel Paubert , Madhavan Srinivasan Cc: mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, paulus@samba.org, anton@samba.org, npiggin@gmail.com Date: Tue, 15 Nov 2016 20:35:44 +1100 In-Reply-To: <20161115080644.GA23527@visitor2.iram.es> References: <1479146692-15726-1-git-send-email-maddy@linux.vnet.ibm.com> <1479146692-15726-12-git-send-email-maddy@linux.vnet.ibm.com> <20161115080644.GA23527@visitor2.iram.es> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, 2016-11-15 at 09:06 +0100, Gabriel Paubert wrote: > > I'm really wondering whether this is the kind of thing that would > benefit from transactions. But transactional memory was only implemented > on Power7 and later IIRC, and we still need to support machines without > transactional memory.  Power8 and later. Also this is about *local* atomics not general atomics, so the overhead of starting a transaction in that case is way way higher than the proposed implementation. Cheers, Ben.