From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from gentwo.org (gentwo.org [62.72.0.81]) (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 9270C279DC8 for ; Fri, 10 Apr 2026 10:24:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=62.72.0.81 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775816678; cv=none; b=G/9L0XwcL6kNzX+3xa81C6fa7qdZ+ZOf2k+Ep6Vy+PQphUpH0XcNRkQcJpeSe0X/mMFwChdPWc/vRAZyRHxJSpxwyqL+0qZVgZYyje5EqQdhAVB+0uLynDtaHwpBcsnUwN9Tm1FURwRLvOXGzjpgO5SeMJPYAwyAgmaGeyea81Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775816678; c=relaxed/simple; bh=03t8udNgjEw5kKsyxwAt5MOGVETnhJlUQnBuEMAtark=; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References: MIME-Version:Content-Type; b=QLkmu8rIO6S5Q/+6jW8U9wySWh1QJ/eX+nbpj0S2XmycEMx1H/nFe/XSJpnxlXcwiQVJTvBvtzJHp+MXJqxRtmNORJnXh0+IezJD9mtQsYDH96rw7daDckD/esMpFBR/L612zYRoEguDVaqeO5UGDpCVREp1jK/N/c/C9RT8nGE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=gentwo.org; spf=pass smtp.mailfrom=gentwo.org; dkim=pass (1024-bit key) header.d=gentwo.org header.i=@gentwo.org header.b=W9A0yhlH; arc=none smtp.client-ip=62.72.0.81 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=gentwo.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gentwo.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=gentwo.org header.i=@gentwo.org header.b="W9A0yhlH" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gentwo.org; s=default; t=1775815962; bh=03t8udNgjEw5kKsyxwAt5MOGVETnhJlUQnBuEMAtark=; h=Date:From:To:cc:Subject:In-Reply-To:References:From; b=W9A0yhlHTl6OYgNFVQXoCfP3RbDl0x1upKfUokGDbzRhMk8OVwCPCzY4Jd7Jfzecb xN3ycty7b11QQsrK4EtrC3QW+g0+AWTK7Paln7dkk8QPhsKaz7jmjUaTl/mOIsUTje Wncwxuh429Xe5ivXfXop99S3OAmblbrx3WZ7hly8= Received: by gentwo.org (Postfix, from userid 1003) id 359A0401EB; Fri, 10 Apr 2026 03:12:42 -0700 (PDT) Received: from localhost (localhost [127.0.0.1]) by gentwo.org (Postfix) with ESMTP id 33F4E401AF; Fri, 10 Apr 2026 03:12:42 -0700 (PDT) Date: Fri, 10 Apr 2026 03:12:42 -0700 (PDT) From: "Christoph Lameter (Ampere)" To: "Vlastimil Babka (SUSE)" cc: Ming Lei , Harry Yoo , Hao Li , Andrew Morton , David Rientjes , Roman Gushchin , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/3] slab: decouple pointer to barn from kmem_cache_node In-Reply-To: <20260311-b4-slab-memoryless-barns-v1-1-70ab850be4ce@kernel.org> Message-ID: References: <20260311-b4-slab-memoryless-barns-v1-0-70ab850be4ce@kernel.org> <20260311-b4-slab-memoryless-barns-v1-1-70ab850be4ce@kernel.org> 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 On Wed, 11 Mar 2026, Vlastimil Babka (SUSE) wrote: > The pointer to barn currently exists in struct kmem_cache_node. That > struct is instantiated for every NUMA node with memory, but we want to > have a barn for every online node (including memoryless). Is this breaking the 1-1 association of kmem_cache to numa nodes? I would think you needd local per cpu queues on a memoryless node for performance but not fake node structures. Per node access is already serialized via locks and therefore slow. If you break the association of per cpu queues to cpu and kmem_cache_node to numa_nodes then the code may get complicated.