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 273D41DA21 for ; Wed, 7 May 2025 14:27:42 +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=1746628063; cv=none; b=mTCa5pNYGgZbfdb0fXizYQUaRKso3gwLtnfNGGJCzGSxyrUFbqTn8Wlx5isk8Jv7/2YiQaOhW/DGoOXCoJUyqjulWx/5J8dTK1+NyjwesMmzYCPfjxtz76q+chRiv8Qo53DAcZpL5fySW7wer/1wGX+tjGQyuXKz8H/ZP6JE5ZE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746628063; c=relaxed/simple; bh=C9fIKaNn0BiGDr8jq7bKKwMZd+UwkkXpZxdlLtzwN+s=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ERuHSYNqMsPWAfKOVgjzFyEF1U8cTtMEUprNTmM/JuGQWfQa27qctcN7RRAvm8lo/xB4AZXCEDdUsKOBiGLuvbiyBcbwJshgDkQO244vl+FRqAnTF6nwwbVohKDQBLRWGwxQSY0RnSmsaLnPccqMgUw9WXI0e+yfol3UczVxb5I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=b2PS1S9Z; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="b2PS1S9Z" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4E847C4CEE2; Wed, 7 May 2025 14:27:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746628062; bh=C9fIKaNn0BiGDr8jq7bKKwMZd+UwkkXpZxdlLtzwN+s=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=b2PS1S9ZSOX+CsB3CRUoudt+OGenobhSw9wB8itYG6KYmF6DM7HrNw2fEhCxV06nW 6Yqc9B99cU9Wp8zOA4JBVFWuZbKgKJKCTokS7rUzNoUoJUeWYza3McozsuWFaNXOh4 6y+lx5LudN8FAXc23wALNdbIu3yF0nTAOCOTq7FJJqBXXZYstYxHiRA/2QfgvVnA0c j1gRfSqVeDM8ZmoYc/ozK8/Pg35/gR5s6KO5mqbOcgLJ4NhqLyiHyksPZEbiaFrcoi WcUxSlIud6FHVhTcTJPJpXuPfwh+1jSfbKotr5UKPsXQr6HXxpH+JyPmIZASa+THaO EWcnHlaCDFF+g== Date: Wed, 7 May 2025 16:27:40 +0200 From: Frederic Weisbecker To: Gabriele Monaco Cc: linux-kernel@vger.kernel.org, Thomas Gleixner , Waiman Long Subject: Re: [PATCH v4 2/5] timers: Add the available mask in timer migration Message-ID: References: <20250506091534.42117-7-gmonaco@redhat.com> <20250506091534.42117-9-gmonaco@redhat.com> <3f54534266f4405fc3c6943599edd9be88becd57.camel@redhat.com> <9b96acdb43b80f067a34b83c5fe9fc3e79f1e3a4.camel@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=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Le Wed, May 07, 2025 at 03:54:32PM +0200, Gabriele Monaco a écrit : > > > On Wed, 2025-05-07 at 15:40 +0200, Frederic Weisbecker wrote: > > Le Wed, May 07, 2025 at 02:46:39PM +0200, Gabriele Monaco a écrit : > > > > > > I'm not so sure about this one though. > > > As far as I understand [1], is preventing the user from setting > > > different CPUs while doing isolcpus=nohz, and nohz_full= (which is > > > now > > > equivalent). But I seem to be able to do isolcpus=0-3 and > > > nohz_full=4-7 > > > without any problem and I believe I'd hit the issue you're > > > mentioning. > > > > Duh! > > > > > (The same would work if I swap the masks as 0 cannot be nohz_full). > > > > Unfortunately 0 can be nohz_full... > > Well, I haven't found what enforces it, but I wasn't able to set 0 as > nohz_full, no matter what I tried on x86 and arm64. Not sure if 0 was > just by chance in this case (I'm guessing it has something to do with > tick_do_timer_cpu, I'm not quite familiar with this code). Ah looks like you need CONFIG_PM_SLEEP_SMP_NONZERO_CPU. IIUC it's only powerpc. You can try to deactivate CONFIG_SUSPEND and CONFIG_HIBERNATE_CALLBACKS otherwise. Thanks. -- Frederic Weisbecker SUSE Labs