From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 121C718A6DB for ; Fri, 6 Feb 2026 15:20:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770391258; cv=none; b=PPnDwgPgZQwwUtZFFd4M20wUcBwwE53/n+zEb4n01eAXAwp6ByGw8KzKi4vyKGQ8E/EIjFcTCZmqcWPp69ACYG5qCnPWS20UXc7i3CSgCmDgznWzJ08TTIkUuj0ZF0ewnmXRm9nYhjs0aqIo1rKgcm55Wj9Ue5YoovDf50UIc9k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770391258; c=relaxed/simple; bh=m9TLokuC5rGVZdojl+bDurZF6xBfwIKD9MiN3qlHtRk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=D+ozdkzm02CDOOF492z2jHDlfIJ6Yudo+VdEvq2f9OshII13+ot6jUUYyg968b7CACpLEaK1WnP6sEAmsf9nKkZbXqhSX6LCKmo/ivwlf20uJfopE9TNT+Eh7XyPMw3aTRsFo9Tc+rlgCqg5qRTz+3majnMAAuJ4+jFOY0zCFxQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=IZQ9RseS; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="IZQ9RseS" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1770391257; 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: in-reply-to:in-reply-to:references:references; bh=m9TLokuC5rGVZdojl+bDurZF6xBfwIKD9MiN3qlHtRk=; b=IZQ9RseSZVIezVj/G95DnKlGMareumtSDH074/z7OpOmGWttd9gaXtK2G0CxgLVoovDcVT HR0GGW/+/7Z3W1Ge8TsGWxka7FSGovvklbIrViZCfDRFylXPY/OrJyMOc/eLxEdpJWiO+a haKqRp3x9Ds1vzK6ZgPX40crAJybrsU= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-5-ECvfvB9IP0O8Uukw_JZm4w-1; Fri, 06 Feb 2026 10:20:54 -0500 X-MC-Unique: ECvfvB9IP0O8Uukw_JZm4w-1 X-Mimecast-MFC-AGG-ID: ECvfvB9IP0O8Uukw_JZm4w_1770391251 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 2C61B1955F12; Fri, 6 Feb 2026 15:20:51 +0000 (UTC) Received: from tpad.localdomain (unknown [10.22.74.16]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 6DC6B18003F5; Fri, 6 Feb 2026 15:20:49 +0000 (UTC) Received: by tpad.localdomain (Postfix, from userid 1000) id CADA64015C638; Fri, 6 Feb 2026 12:20:28 -0300 (-03) Date: Fri, 6 Feb 2026 12:20:28 -0300 From: Marcelo Tosatti To: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org Cc: Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Vlastimil Babka , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Leonardo Bras , Thomas Gleixner , Waiman Long , Boqun Feng Subject: Re: [PATCH 1/4] Introducing qpw_lock() and per-cpu queue & flush work Message-ID: References: <20260206143430.021026873@redhat.com> <20260206143741.525190180@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260206143741.525190180@redhat.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 On Fri, Feb 06, 2026 at 11:34:31AM -0300, Marcelo Tosatti wrote: > Some places in the kernel implement a parallel programming strategy > consisting on local_locks() for most of the work, and some rare remote > operations are scheduled on target cpu. This keeps cache bouncing low since > cacheline tends to be mostly local, and avoids the cost of locks in non-RT > kernels, even though the very few remote operations will be expensive due > to scheduling overhead. Forgot to mention: patchset is against Vlastimil's slab/next tree.