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[23.128.96.18]) by mx.google.com with ESMTP id dm24si12233405edb.297.2021.04.07.14.27.52; Wed, 07 Apr 2021 14:28:15 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=casper.20170209 header.b=v56zcA69; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245431AbhDGP4E (ORCPT + 99 others); Wed, 7 Apr 2021 11:56:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39100 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232716AbhDGP4E (ORCPT ); Wed, 7 Apr 2021 11:56:04 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9EB81C061756; Wed, 7 Apr 2021 08:55:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=ZN4QPdG1dWY6PBo4DSX5jrwf0CE9CsAs0+P/fZZM2Q4=; b=v56zcA69Axw8XFUBNIHFOZoenq iUwADmybOT9cRYlkoTELmY4GiYo9Kmzl1EZ678sgaqNY87YCrmckChlCNEv7eE4zYmyUzLAvrhY3W qPFqCtxoQn11hJvCjtdgYsSdfkm3ty/AsejW0/O4m6CZ9gT9vCRtU4OURHA0vqk7QEvzxsprnKH6D 6b8mLKd42nleucfHxTd22W1tZhXpty0Ct5NjmKw4ggQcRug1NLYPcbIfEqqojKra0hTXt8+J1Dvjf Uus5cbh2eupcBfyVoSkwl7KJoyalB8DWrAKz2Z5741s+TxaQ3BUgDlk0wRRo2/FX4aDIxsD2w2+me KBb63rWw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1lUATs-00EhxJ-PW; Wed, 07 Apr 2021 15:52:43 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 6F1AF300219; Wed, 7 Apr 2021 17:52:36 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 61DB52BF09264; Wed, 7 Apr 2021 17:52:36 +0200 (CEST) Date: Wed, 7 Apr 2021 17:52:36 +0200 From: Peter Zijlstra To: Christoph =?iso-8859-1?Q?M=FCllner?= Cc: Christoph Hellwig , Guo Ren , linux-riscv , Linux Kernel Mailing List , linux-csky@vger.kernel.org, linux-arch , Guo Ren , Will Deacon , Ingo Molnar , Waiman Long , Arnd Bergmann , Anup Patel Subject: Re: [PATCH v4 3/4] locking/qspinlock: Add ARCH_USE_QUEUED_SPINLOCKS_XCHG32 Message-ID: References: <1616868399-82848-4-git-send-email-guoren@kernel.org> <20210407094224.GA3393992@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 07, 2021 at 04:29:12PM +0200, Christoph M?llner wrote: > The comparison with sparc64 is not applicable, as sparc64 does not > have LL/SC instructions. Sparc64 has CAS, without hardware fwd progress. It has to do software backoff for failed CAS in order to do software fwd progress.