From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) (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 D8A9C1A2562; Thu, 1 Aug 2024 01:27:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.255 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722475624; cv=none; b=bWh4c1PdvIV1O9KFqlmzsBhpVbVE+e/Bz2sLuPY/y6CvBhp7BiXksqT6QdSES0JlRo8T1lfNUz2OpwNKnIU6LQajchnxR8Sb1pBcnyDYLJR0hqkn9wIaGyTcmlc0oPy8lXW4Sst0k2uE4j/URAK8XM/81AlAujTLjqB46tabuNY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722475624; c=relaxed/simple; bh=NyUJU5qt9KOZ5V2FlZXxo9KiqYr69JBvG75ao6KughU=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=jz7Ib3XCggv5WLCqqTdVn2jiiOHi1iXuaqxWXCr/44I3kNRZWipJCN1pWRVoWf2QLBsIcFoHOlG3DG52iswSjoJuLwBrGBpWDKffEfcS4AyKqweF+gdaS2zrH7wy6Ffud6jguaNRwVTG72uXwvM7xare17FzmlRFiuOjSJxxUQ8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.255 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.163.48]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4WZBBv2kjRz1L927; Thu, 1 Aug 2024 09:26:47 +0800 (CST) Received: from kwepemi100008.china.huawei.com (unknown [7.221.188.57]) by mail.maildlp.com (Postfix) with ESMTPS id 799C718009B; Thu, 1 Aug 2024 09:26:59 +0800 (CST) Received: from [10.67.109.254] (10.67.109.254) by kwepemi100008.china.huawei.com (7.221.188.57) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.39; Thu, 1 Aug 2024 09:26:58 +0800 Message-ID: <3855e3a4-769b-5162-0747-cf72b94f7089@huawei.com> Date: Thu, 1 Aug 2024 09:26:58 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.2.0 Subject: Re: [PATCH] ARM: support PREEMPT_DYNAMIC Content-Language: en-US To: "Russell King (Oracle)" CC: , , , , , , , , , , , , References: <20240620090028.729373-1-ruanjinjie@huawei.com> <79a3de7c-21da-12ce-8372-9c9029c237ac@huawei.com> <034499ea-2cd6-8775-ee94-771cbecd4cdb@huawei.com> From: Jinjie Ruan In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To kwepemi100008.china.huawei.com (7.221.188.57) On 2024/7/31 18:14, Russell King (Oracle) wrote: > On Wed, Jul 31, 2024 at 06:03:11PM +0800, Jinjie Ruan wrote: >> On 2024/7/31 16:24, Russell King (Oracle) wrote: >>> On Wed, Jul 31, 2024 at 10:07:53AM +0800, Jinjie Ruan wrote: >>>>> #ifdef CONFIG_PREEMPTION >>>>> +#ifdef CONFIG_PREEMPT_DYNAMIC >>>>> + bl need_irq_preemption >>>>> + cmp r0, #0 >>>>> + beq 2f >>>>> +#endif >>> >>> Depending on the interrupt rate, this can be regarded as a fast path, >>> it would be nice if we could find a way to use static branches in >>> assembly code. >> It seems to be hard to use static keys in assembly code. >> >> By the way, currently, most architectures have simplified assembly code >> and implemented its most functions in C functions. Does arm32 have this >> plan? > > arm32 is effectively in maintenance mode; very little active development > is occuring. So, there are no plans to change the code without good > reason (as code changes without reason will needlessly affect its > stability.) Thank you for helping me with my question. >