From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 13ED9C433EF for ; Mon, 25 Oct 2021 18:25:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ED86160E0B for ; Mon, 25 Oct 2021 18:25:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233524AbhJYS2P (ORCPT ); Mon, 25 Oct 2021 14:28:15 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:31935 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233217AbhJYS2I (ORCPT ); Mon, 25 Oct 2021 14:28:08 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1635186345; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=WmLX7TLtZ9IDJ1JQ+2m7C+nUTKDcem4HGFPTzsvzRlk=; b=Wv+Bn4dxhZd55LviAVyViBWcPOU0Rp9ilELfxoHmfPRFMsMTnWyr1KV+vnUb7HxdBQFDfC 8u0icaeLpBJuKsHO4IauhD6FqbM2usvJnAy9dRHnG8kAyJQ3OJOmAhBHBf4caR9CwOQhVl MPkAtyhKscX5eicRiWleuN3BY3eHf84= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-80-pXULrgXMNu2BFbQqJnWKPA-1; Mon, 25 Oct 2021 14:25:40 -0400 X-MC-Unique: pXULrgXMNu2BFbQqJnWKPA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3722410B3959; Mon, 25 Oct 2021 18:25:37 +0000 (UTC) Received: from llong.remote.csb (unknown [10.22.18.111]) by smtp.corp.redhat.com (Postfix) with ESMTP id 28C21100763D; Mon, 25 Oct 2021 18:25:33 +0000 (UTC) Subject: Re: [PATCH] locking: remove spin_lock_flags() etc To: Arnd Bergmann Cc: Peter Zijlstra , Ingo Molnar , Will Deacon , Arnd Bergmann , Boqun Feng , Jonas Bonn , Stefan Kristiansson , Stafford Horne , "James E.J. Bottomley" , Helge Deller , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Alexander Gordeev , Linux Kernel Mailing List , linux-ia64@vger.kernel.org, Openrisc , Parisc List , linuxppc-dev , linux-s390 References: <20211022120058.1031690-1-arnd@kernel.org> <2413f412-a390-bbc0-e848-e2a77d1f0ab3@redhat.com> From: Waiman Long Message-ID: Date: Mon, 25 Oct 2021 14:25:32 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On 10/25/21 11:44 AM, Arnd Bergmann wrote: > On Mon, Oct 25, 2021 at 5:28 PM Waiman Long wrote: >> On 10/25/21 9:06 AM, Arnd Bergmann wrote: >>> On s390, we pick between the cmpxchg() based directed-yield when >>> running on virtualized CPUs, and a normal qspinlock when running on a >>> dedicated CPU. >> I am not aware that s390 is using qspinlocks at all as I don't see >> ARCH_USE_QUEUED_SPINLOCKS being set anywhere under arch/s390. I only see >> that it uses a cmpxchg based spinlock. > Sorry, I should not have said "normal" here. See arch/s390/lib/spinlock.c > for their custom queued spinlocks as implemented in arch_spin_lock_queued(). > I don't know if that code actually does the same thing as the generic qspinlock, > but it seems at least similar. Yes, you are right. Their queued lock code looks like a custom version of the pvqspinlock code. Cheers, Longman