From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 31B9834B66F for ; Thu, 16 Jul 2026 19:22:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784229773; cv=none; b=Qu5O39EaB17i7KKtrFejRftt8XX5tOFiG4oC/rHyP1/fzPGyrN6g5LL/8KpQGFvTjier4mz/qrim+bUbBsyS0ewSXp1LxNHDL1Evjg1Ms5TxIg/asiRuZ7FsX39uZaJwJQqPu61U2ROvE9TGjDRimkr5pMtJN/8ibnKX4XIPDMg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784229773; c=relaxed/simple; bh=OD+GbhTvl9utGu/MDGx+Qt63vICGtJ3jSGw7EawNVuQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=OR6QjXHo3byhgolGZrAGG/uCwd+RaOl7mzRFVZ8hwZEcELneeuhM7ctuW+i2bl1FZGxzyN+AzZq42YBkvRPTPcB42IFVwAWC+9/2SBWh8W73hjwSIi+DJ0F6O7sQv8jRp9p1oI16xyyz07w3z82k+Xu7UQhjYjp3UrFVs6Fc6aA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JvClZkv8; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="JvClZkv8" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 910CD1F000E9; Thu, 16 Jul 2026 19:22:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784229771; bh=gRUdiqDzJvQrHY9f9gErp5FDOGSoVslngA136Hzl8Qc=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=JvClZkv8V6i2l6bR2OhOoI4BnPGiIFc2tKq/qmC4Zi/zYFtixPqugMHxad++HU9KE M0dnUK8iqv7ChxW1sS0rxK6KRZqgIOPh8FoSys0hkvz+88xj0gxBDXOVD4GLhc8WDX toZxmcME4Qspsx9QqlI72xGri9GiZXZv4BTYJTOOsDrPxfmQdZmJNTS0LGspV9nfBd WaQQ94YyNXQOIAwj0nXRtR2T4SXPyvt8kfjySOzyNH1nV9QdmnTzeUVicSA9agD9RF 0G7pJ2H8rcnWIV1o1twqin3oIps8V7/C7+/XA6j2nf56zFtfR0IHytyqpuuZMmyQnd qCMYxh2di4lAw== Date: Thu, 16 Jul 2026 09:22:50 -1000 From: Tejun Heo To: Breno Leitao Cc: Lai Jiangshan , linux-kernel@vger.kernel.org, marco.crivellari@suse.com, frederic@kernel.org, kernel-team@meta.com Subject: Re: [PATCH RFC 0/3] Refactor the workqueue allocations Message-ID: References: <20260714-tejun1-v1-0-024d59241386@debian.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 Content-Disposition: inline In-Reply-To: <20260714-tejun1-v1-0-024d59241386@debian.org> Hello, On Tue, Jul 14, 2026 at 04:41:46AM -0700, Breno Leitao wrote: ... > 1) wqattrs is an unbound concept and apply_workqueue_attrs_locked() rejects > non-unbound wqs. Should we leverage wqattrs in per-cpu workqueues as well, > so the unification can happen later (apply_workqueue_attrs_locked())? I'm not sure adding wqattrs to percpu workqueues makes sense. Wouldn't the shape more be like unbound workqueue subsuming percpu workqueue? > 2) If percpu becomes a WQ_AFFN_CPU affinity setting, how should max_active be > treated? WQ_AFFN_CPU is unbound today, so it would inherit per-node > accounting (wq_node_nr_active) and lose percpu's per-cpu max_active > (pwq->nr_active). I think it probably would be better to introduce a separate affinity scope than modifying WQ_AFFN_CPU. Something which indicates that concurrency management is in effect and max_active is per-cpu. > 3) What end state are you aiming for? Keep WQ_PERCPU as a thin flag over > unified internals (single install path, per-cpu accounting special-cased) > with WQ_UNBOUND staying for now -- or something more radical (the flags gone > entirely, percpu purely an affinity value)? Keeping WQ_PERCPU as a shorthand for specifying the percpu scope makes sense to me. Thanks. -- tejun