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 E5456249E0 for ; Wed, 17 Jan 2024 19:32:39 +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=1705519961; cv=none; b=GkUTssn9SlYwFRYSj1IEmnhw0KjgR3pr0Ick6xdfvE2uCMpGk1Ri0WpV0ColVWgD/ALfD/5DZ6/p12aqTVq8v57A52CTRKsuJ8Ok6V0F028saXAbBT02RSiXgmmYuRPsFVV5Nm0QWOPw3Fnvwi2MWsy+AG8W9ea9wzQUxBtInqU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705519961; c=relaxed/simple; bh=QvqQHYPeITGXtLTPrNEHN+dZrrNa20vk0SDYMEEzQq4=; h=DKIM-Signature:Received:X-MC-Unique:Received:Received:Message-ID: Date:MIME-Version:User-Agent:Subject:Content-Language:To:Cc: References:From:In-Reply-To:Content-Type:Content-Transfer-Encoding: X-Scanned-By; b=IRff2r3ATOJ/5WkaXxi3XhFD2oJlnwxUUCrNpVm3t9C/DPh7DId/Of5/9mK9U0D/ldFETmEK3wocPkgpPCPCq/FMFUJR4vBP7jDVaopHuULnOIGLn4W4wXDRxTAAocBiuBP/xTCj7yjSU5Hjaviw928sZaC4JtHmciLB6tzY914= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none 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=fe71WRyB; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none 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="fe71WRyB" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1705519958; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=bfUgfGTy5yRHGk/lV0Z6rRdd4H0q3HaJTSR3wYzs52E=; b=fe71WRyBxTlp+DXlJthRFj9nUaPQrS8lygIZgqViCnLD3ThMZhFFvb7PWrsJI1Ygoowc5D T6ZS8I8udS3HudbU164lqGaRAeN682GIupkBgAKEaU8bNtmUqIZuZSTuJ5WXkldV9M9BjL wCNVZyRGDE4j66f9Xz4lXFpj+zopSU0= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-515-Gayb9gvBNdCBCNZGvG7HOQ-1; Wed, 17 Jan 2024 14:32:35 -0500 X-MC-Unique: Gayb9gvBNdCBCNZGvG7HOQ-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (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 mimecast-mx02.redhat.com (Postfix) with ESMTPS id 0EF1A2806400; Wed, 17 Jan 2024 19:32:35 +0000 (UTC) Received: from [10.22.16.147] (unknown [10.22.16.147]) by smtp.corp.redhat.com (Postfix) with ESMTP id AE540FEEE; Wed, 17 Jan 2024 19:32:34 +0000 (UTC) Message-ID: <72e4a971-96e5-44b7-b348-bbdb68e54b40@redhat.com> Date: Wed, 17 Jan 2024 14:32:34 -0500 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 3/4] kernel/workqueue: Distinguish between general unbound and WQ_SYSFS cpumask changes Content-Language: en-US To: Tejun Heo , Juri Lelli Cc: Lai Jiangshan , Aaron Tomlin , Valentin Schneider , linux-kernel@vger.kernel.org References: <20240116161929.232885-1-juri.lelli@redhat.com> <20240116161929.232885-4-juri.lelli@redhat.com> From: Waiman Long In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.5 On 1/17/24 12:12, Tejun Heo wrote: > Hello, > > On Wed, Jan 17, 2024 at 02:06:08PM +0100, Juri Lelli wrote: >>> This looks rather hacky. Can you elaborate how the current code misbehaves >>> with an example? >> I was trying to address the fact that ordered unbound workqueues didn't >> seem to reflect unbound_cpumask changes, e.g. >> >> wq_unbound_cpumask=00000003 >> >> edac-poller ordered,E 0xffffffff 000000ff kworker/R-edac- 351 0xffffffff 000000ff >> >> vs. >> >> edac-poller ordered,E 00000003 kworker/R-edac- 349 00000003 >> >> with the patch applied. But honestly, I'm now also not convinced what >> I'm proposing is correct, so I'll need to think more about it. >> >> Can you please confirm though that ordered unbound workqueues are not >> "special" for some reason and we would like them to follow >> unbound_cpumask changes as normal ubound workqueues? > They aren't special and should follow the normal unbound workqueue cpumask. My impression is that changing the workqueue cpumask of ordered unbound workqueue may break the ordering guarantee momentarily. I was planning to look into this further to see if that is true when I have time. If it is not a concern, we should certainly apply the global unbound cpumask change to those workqueues as well. Cheers, Longman