Received: by 2002:a05:6358:3188:b0:123:57c1:9b43 with SMTP id q8csp330822rwd;
        Tue, 16 May 2023 01:27:19 -0700 (PDT)
X-Google-Smtp-Source: ACHHUZ5/rI28tANaTcEyaY9KEAdMasc79rufiUMrn1gCZ4RkRmrZkuVuKPLIYrfLAlCfF+omDK77
X-Received: by 2002:a17:90b:1c86:b0:250:461:ae65 with SMTP id oo6-20020a17090b1c8600b002500461ae65mr36406086pjb.5.1684225639161;
        Tue, 16 May 2023 01:27:19 -0700 (PDT)
ARC-Seal: i=1; a=rsa-sha256; t=1684225639; cv=none;
        d=google.com; s=arc-20160816;
        b=GLbFaC+h6hHyB/8ceXrCOy6cD2ja2FSvYIfqgteAj6Fkzw1uARZZimJI0vZ9gXfhQp
         AMcdj0COr+Qy1iJ/+YUpA28kauy2AhGoJmuKTFWerTr38A49zq1jpjR3Mh1R+zbjD0i6
         2B2+8/lLDsdTGeemdxuzW999YUU4LH0205XVVmtWKTwQoEVzmE/Gu3bOeMsqUvvNJ+Nj
         M7MSxHnAjRyl2IGgxQ0DKD01Ot5xlcPtVr7GvD7xponA0n4Tbd3QrjFZw8HOoSzlmqFD
         C2cTnE72HvDAv71yRLh33xtX9662BHdptmqiShr21cQFm0y3WEz7GRGRSQFsE2k5n6+1
         rEfQ==
ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816;
        h=list-id:precedence:mime-version:references:message-id:in-reply-to
         :subject:cc:to:from:date:dkim-signature;
        bh=hpU/oGsJKhftsTiTA4eWWU1ahLkljMFSgkNMxC+KLu8=;
        b=GbQrKw6GXru6QSpW8ZWU7LTCUonThHSan6FeK/J5AaIr9t91TMpNTPFXEgF+v6cjiy
         dNugPB92zRheKnf+v+X+v0c7rxUdrKbTBLH1GtNDnCD96XXtO6RgsZIjhSLbJkyhq62Y
         kd5YKQrF+cSVBmnuxXDoe/nDtlHvx/ebmS3+FHpnEyti6zpcVn2PJ0I1bKuuY4j8n57K
         WzjDce5TH/52oIps7+hY7Oav2cBNqbL13s4UszMBVkqEuPB7KHHDgMdxBCRRWRYSUaoQ
         xVjP46S+bjdGxLcm53XLw8WIexypr1wy+lpA4GnMKK5aLNvs9diH0pojxYUkEDRj2R19
         mHBw==
ARC-Authentication-Results: i=1; mx.google.com;
       dkim=pass header.i=@gentwo.de header.s=default header.b=ImdhTrlz;
       spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org;
       dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=gentwo.de
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20])
        by mx.google.com with ESMTP id bx6-20020a17090af48600b00230a8355ff1si1179524pjb.181.2023.05.16.01.27.04;
        Tue, 16 May 2023 01:27:19 -0700 (PDT)
Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Authentication-Results: mx.google.com;
       dkim=pass header.i=@gentwo.de header.s=default header.b=ImdhTrlz;
       spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org;
       dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=gentwo.de
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S231605AbjEPITi (ORCPT <rfc822;0x7f454c46@gmail.com> + 99 others);
        Tue, 16 May 2023 04:19:38 -0400
Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41136 "EHLO
        lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S230379AbjEPITh (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Tue, 16 May 2023 04:19:37 -0400
X-Greylist: delayed 629 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Tue, 16 May 2023 01:19:34 PDT
Received: from gentwo.de (gentwo.de [161.97.139.209])
        by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E1D9CD1
        for <linux-kernel@vger.kernel.org>; Tue, 16 May 2023 01:19:34 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gentwo.de; s=default;
        t=1684224542; bh=MGnFW31psCJp5sPWKx6WOpe7YpGa7jmZLWFLPIu43/8=;
        h=Date:From:To:cc:Subject:In-Reply-To:References:From;
        b=ImdhTrlz2TqRRcSvdWzpxHRRWXoijUmOuAdWQqj2quRa/ovXFZYWeEIaReDrwjfrO
         TnljqfKs5ulPVfG+RoWq2AE72R/O4HEu7YtMjmbNB62p2M6BtYxDSGQBP1KpaFveoJ
         dy0gVMm/nL9KJRVQJbnDOi7WxFYOpDAo+OeDY1UBio2M+QwV/fyzZtDlQFqvyxgX0e
         Sv5kCwQBfFaiT0TrrX1btJTwuHwvmLD77NnSw7oniRPxd+OjPYgPkrH94EXoxmuFey
         QFwAl6W1yApZpSevVNfVNzPsXLVLu4aSRJZba0bRiySAbUdXW49Fb+uI94wdFSk32k
         K7IYDUeOjhlxg==
Received: by gentwo.de (Postfix, from userid 1001)
        id 3E76AB00191; Tue, 16 May 2023 10:09:02 +0200 (CEST)
Received: from localhost (localhost [127.0.0.1])
        by gentwo.de (Postfix) with ESMTP id 3CFF1B0009A;
        Tue, 16 May 2023 10:09:02 +0200 (CEST)
Date:   Tue, 16 May 2023 10:09:02 +0200 (CEST)
From:   Christoph Lameter <cl@gentwo.de>
To:     Marcelo Tosatti <mtosatti@redhat.com>
cc:     Aaron Tomlin <atomlin@atomlin.com>,
        Frederic Weisbecker <frederic@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Russell King <linux@armlinux.org.uk>,
        Huacai Chen <chenhuacai@kernel.org>,
        Heiko Carstens <hca@linux.ibm.com>, x86@kernel.org,
        Vlastimil Babka <vbabka@suse.cz>,
        Michal Hocko <mhocko@suse.com>
Subject: Re: [PATCH v8 00/13] fold per-CPU vmstats remotely
In-Reply-To: <20230515180015.016409657@redhat.com>
Message-ID: <b1f75dca-5d86-125f-bbba-7b575b62d21@gentwo.de>
References: <20230515180015.016409657@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_PASS,SPF_PASS,
        T_SCC_BODY_TEXT_LINE,URIBL_BLOCKED autolearn=ham autolearn_force=no
        version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

The patchset still modifies the semantics of this_cpu operations semantics
replacing the lockless RMV operations with locked ones. One of the
rationales for the use  this_cpu operations is their efficiency since
locked RMV atomics are avoided. This patchset destroys that functionality.

If you want locked RMV semantics then use them through cmpxchg() and
friends. Do not modify this_cpu operations by changing the implementation
in the arch code.