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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5A289C61DA4 for ; Thu, 16 Mar 2023 00:07:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232725AbjCPAHl (ORCPT ); Wed, 15 Mar 2023 20:07:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56736 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233087AbjCPAHh (ORCPT ); Wed, 15 Mar 2023 20:07:37 -0400 X-Greylist: delayed 583 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Wed, 15 Mar 2023 17:07:07 PDT Received: from gentwo.de (gentwo.de [161.97.139.209]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 31D1361ABF for ; Wed, 15 Mar 2023 17:07:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gentwo.de; s=default; t=1678924580; bh=HELdY/NMjq+c5Rkpy0uqmSSxU4Vqd4oCpA5llE3DmGc=; h=Date:From:To:cc:Subject:In-Reply-To:References:From; b=LgRDJVwg3d/6rGzJ9a0bB+aym1i26mqReOySLxyl8GMB/mx/jZzur1vxnf4yUISHk 35co2Hmg7NXz1e3QY82k3e8alRSxoLDemqlRX+qQ69+W+03uuIG101n3psWzBHavcG 6uSl1me/2z/fT4nXsRN4KePOf4q/Me71a74PWHHIxvMJco0L6ULm4WuKtapibXRaHt GsSTbw5/VApSHCByZn+UVsfaeO+akoYBegMGh7KD8IIQlsSwLxdQKo+zL7NBhTlIgM /W2FP6FnEWbY0o5jqN7UIaFfSO8/E/TLQLc4DfpyXlX5rt+bWITWhRVGlufyC9ez7/ C5Is9QYP3hqoQ== Received: by gentwo.de (Postfix, from userid 1001) id 488FDB00162; Thu, 16 Mar 2023 00:56:20 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by gentwo.de (Postfix) with ESMTP id 46DF1B000AB; Thu, 16 Mar 2023 00:56:20 +0100 (CET) Date: Thu, 16 Mar 2023 00:56:20 +0100 (CET) From: Christoph Lameter To: Marcelo Tosatti cc: Aaron Tomlin , Frederic Weisbecker , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v2 02/11] this_cpu_cmpxchg: ARM64: switch this_cpu_cmpxchg to locked, add _local function In-Reply-To: <20230209153204.683821550@redhat.com> Message-ID: References: <20230209150150.380060673@redhat.com> <20230209153204.683821550@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 9 Feb 2023, Marcelo Tosatti wrote: > Goal is to have vmstat_shepherd to transfer from > per-CPU counters to global counters remotely. For this, > an atomic this_cpu_cmpxchg is necessary. The definition for this_cpu_functionality is that it is *not* incurring atomic overhead and it was introduced to *avoid* the overhead of atomic operations. This sabotages this_cpu functionality,