From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 4910C86353 for ; Fri, 9 Jan 2026 22:47:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767998868; cv=none; b=tc7VbGGAz2pKTiYwAVCxLKbV92dUIGWJVHq9Fvd2NUka2Y4zly94wBWgf+uO+NBl01UOrvBnWHP9KCklJpuX6FfV0Gz3C/NP66K5uJfJ86iCiMA0GtfD6oCmxGqtsAsZvOy8YH5sYG/Jyl6+EkdAEtv2b2ZUc4ShEmY6FOy4PL8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767998868; c=relaxed/simple; bh=KkWyoaazH69njlWOuCDHobwIXtm+lAZ2pODSjI5fOzU=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=aFSSOJ+5SdfcP6F3T8jQFiOoHDPM7X3/r8YlURDDIDH/ZaLC1o9CcwTxtkuHbBSKXd8kQL1yGf+XqEnA2GhVs//Nl2aAHprBEjDP3N7SksJDFNJp8xT2VchGtHmQoP9lMb5ZB3rEaIxxty/60oGWuOErtTSZI0tv2/ZRbrDs8eo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=DQgbwph6; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="DQgbwph6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 85ECDC4CEF1; Fri, 9 Jan 2026 22:47:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1767998867; bh=KkWyoaazH69njlWOuCDHobwIXtm+lAZ2pODSjI5fOzU=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=DQgbwph6m7dF/9+QlPhq1QY2OMfLE5Eh4OzJuzRYcZTyI2e4TsZSLDL+SSTqndeDD BpLev+jJJLKj+5wbay08W/w0rwlMX6P9PgdKOYKb86cBX/yctnF0mwzKnIaWCFjAlK opObSJNO00FETSASBOJ1ZQ5hz/yYaNXQfbIVpb1s= Date: Fri, 9 Jan 2026 14:47:46 -0800 From: Andrew Morton To: Radu Rendec Cc: "Guo, Wangyang" , Thomas Gleixner , linux-kernel@vger.kernel.org, Tianyou Li , Tim Chen , Dan Liang Subject: Re: [PATCH] lib/group_cpus: make group CPU cluster aware Message-Id: <20260109144746.95feaf11e4214cc4895d4039@linux-foundation.org> In-Reply-To: References: <20251024023038.872616-1-wangyang.guo@intel.com> <20251221111047.597248db9868d278c7786f6b@linux-foundation.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) 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=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On Fri, 09 Jan 2026 14:13:32 -0500 Radu Rendec wrote: > > > > This patch improves IRQ affinity by grouping CPUs by cluster within= each > > > > NUMA domain, ensuring better locality between CPUs and their assign= ed > > > > NVMe IRQs. > > > >=20 > > > > Reviewed-by: Tianyou Li > > > > Reviewed-by: Tim Chen > > > > Tested-by: Dan Liang > > > > Signed-off-by: Wangyang Guo > > >=20 > > > Patch hasn't attracted additional review so I'll queue this version f= or > > > some testing in mm.git's mm-nonmm-unstable branch.=A0 I'll add a > > > note-to-self that a changelog addition is desirable. > >=20 > >=20 > > Thanks a lot for your time and support! Please let me know if you have= =20 > > any further comments or guidance. Any feedback would be appreciated. >=20 > With this patch applied, I see a weird issue in a qemu x86_64 vm if I > start it with a higher number of max CPUs than active CPUs, for example > `-smp 4,maxcpus=3D8` on the qemu command line. >=20 > What I see is the `while (1)` loop in alloc_cluster_groups() spinning > forever. Removing the `maxcpus=3D8` from the qemu command line fixes the > issue but so does reverting the patch :) Great, thanks, I'll drop the patch. I have notes here that an updated version is expected anyway. Perhaps due to planned changelog updates. And perhaps hopes for additional info regarding the runtime effects of the change.