From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm2-f12.google.com (mail-wm2-f12.google.com [74.125.225.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C1BB34E0B9A for ; Tue, 29 Sep 2026 21:25:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.225.140 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790717143; cv=none; b=SHTjSXE2orgu7TRmHlfgxZVuW430dg1IsA31K+9IQY9QMQAlmlLX46quSPkGkPR6Tn33D3V3y88vf/9inaSQEY4KKPw65PfVg1+E55jxHLRTD3gCRBzO4xA4ZNrKcby2K3Vh7aV481sL03rGNLOxiYe9nxQQnLzk3qV5It/xsUo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790717143; c=relaxed/simple; bh=Tjs7FwpG8SBJ1qS8KHelfEMZVZQILD7n6hgU4O1XLxw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=I49pA31B3zYZm+aIL0uAgg7YsCULUOMZrKtpI+O1z/GxqmpXYl9aBCIQL1ggRVNmt5/dQ+SULlUz08HI+GzFlIrPUy2UIpgezQeiHgCXkgghvYHq7+1BAQ7aghspFvhNL987vmP68PSkfZvzTU8vvjuDmoLvw1zzL4nWfeiXm8A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=Lr5OZj9j; arc=none smtp.client-ip=74.125.225.140 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Lr5OZj9j" Received: by mail-wm2-f12.google.com with SMTP id 5b1f17b1804b1-49ff9642c57so6413875e9.0 for ; Tue, 29 Sep 2026 14:25:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1790717140; x=1791321940; darn=lists.linux.dev; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=o4P77awGw7CnoZ9LloNVfZMxMXD8dRiBGwj2EdNOf8w=; b=Lr5OZj9j/n5ImzidDJcH6a3IUpDEgc+3KjoDkJKjEDSIqv0n+gxEr+GTf4v1HvKN9R MrqEz+OGV2VyCsG+2yCJ+UkDE5kwN2SuJgElisztf/szX7XhXMWp1jHmv5+TYqf5huKN q8XmcqjI7lSetwyPsF9dVQM62BzkXOSfCLVQHB7oK36QoYkcGUT9HhxjyTEXRjXRO35V 17UIP3wlrNCCS97ck3iREzPG/ciMTRRMzk93TeDWTrtVO6gQLQTjfrFpXqwWeycoGB7J AeSdSL+Y8DmY/RRtIq6+Jbezi/r+bESrK5sHwdPYsvD7VcfNGWIJ720pOGz7LgLf3X+o Ww7w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1790717140; x=1791321940; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=o4P77awGw7CnoZ9LloNVfZMxMXD8dRiBGwj2EdNOf8w=; b=Tymo27UtN4QkdsPXQeN+6+yrne6kCvJeMMHM3AkSZY6us+mdZIeEBznzqjkDsJIP8N j07agWIDm7/y9PRDc/2ZKTfQv43pxGzc3QiFQ5LRKnpKkfUnkFkfoP1wTWdMGwActCDx 2YRjmMtZQXKGxaasigspllYQPEK0uJf/E2qH3gqDSRPXwB+ltyUBZhOUUE2TDBbCgcm0 3W8hkJ/0qrYFsdR/Pq86i+GBauXKWTvDubQbwcwsLLqRejlMZJoriFHz7ty3yOAVj4Nb Tn1D146+0o4vrzcsXDT1JqSOnB46eWfp1HF/VsAoui33N4fvtrv3s1FXMv0XyIjjiUBk upAA== X-Forwarded-Encrypted: i=1; AKwUvBzedfJ1GlNhyDzexPEnWZ8wDMkFGA0dCL1i3Og5a9ccFvAYXsCuj9VjxSGc/r7MGNoapuC5kfWuMhNhTtU7ag==@lists.linux.dev X-Gm-Message-State: AFuF++nJKe9qB8zL4M+rZgZeyO9KpQZDxE0E/guXj741U70NkasR3Y5i pYcFCXpPUVhXJIxOrwQBeLUc8084nG7LLQ8/78cd1O9Ez/ChR5fyjs1p X-Gm-Gg: AYBFou0vSKnm7PmpiuO2UfoqHiRh9zh0xbm/oIPDEVrlByowOaTD1cbfddC1xQburfn c6HsKOzODyDG0CRL8EDXAJBSP6FNbRaHAufq5bT15ZZgsERr4R8+mjZuuaO+M2dp88t7wggZ7ha luZm4vLzQfBoK7awHSsCBAQ/GSJV0eOoWuvau/FzQVNM0xpofYCfpqaQgpmcC6u8GFsMKlSh42/ v7m6CW5Bxbas7PmeO5Gsxcg9ZpASYeiyqX4bCuP/Dyyc39wNLCrP2kkRL9N2DTHrBeSzOQzhWfJ neh56IuKSSS+OgQmmTERSxouJxM2lc9akyWzUffr+wpAj+zNsLVjAHAhSB2WBVek0zmFFESyPI6 shV45FlccfoZzLOPVn/ORmVoF338jfORltU3Ft8caJtELgwD4xm0SHbLMurpIjgKRotgylTIqJr ODdlX31hC1RXXsmfjSiGtBq/bvqGB/zzKHvhdMJT8fwXf40TMDxLmv4fswXtAiE/dNcj9wrkBkD XI5vNdjnhgOeICh+aGlBpdEBbMz2e5f9OFOPjOQOBtgI/PDPCH0HHYSQXQm1WuGBzH8nrD+dAKl shbOs+l9kK3fwd++84EJEUPRixSFkMPTUTPTN3RJOwdn654JTmhiSQ7OT2RQNaZAeyBaRfHmiqM = X-Received: by 2002:a05:600c:c176:b0:49f:fbad:29ae with SMTP id 5b1f17b1804b1-4a015142604mr5797515e9.17.1790717139884; Tue, 29 Sep 2026 14:25:39 -0700 (PDT) Received: from unknown748F3CBA5068 (dynamic-2a02-3100-9c32-f801-9d9d-c89f-9fb1-4ec2.310.pool.telefonica.de. [2a02:3100:9c32:f801:9d9d:c89f:9fb1:4ec2]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a00cfecb39sm118395395e9.7.2026.09.29.14.25.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 29 Sep 2026 14:25:39 -0700 (PDT) Date: Tue, 29 Sep 2026 23:25:37 +0200 From: Karl Mehltretter To: Sebastian Andrzej Siewior Cc: Peter Zijlstra , Thomas Gleixner , Frederic Weisbecker , Clark Williams , Steven Rostedt , Boqun Feng , Lyude Paul , Joel Fernandes , Alexander Potapenko , Marco Elver , Jonathan Corbet , Bradley Morgan , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev Subject: Re: [PATCH v4] softirq: Preserve interrupt context during IRQ exit Message-ID: References: <20260926143505.66024-1-kmehltretter@gmail.com> <20260928082402.1iCSzDzY@linutronix.de> Precedence: bulk X-Mailing-List: linux-rt-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260928082402.1iCSzDzY@linutronix.de> On Mon, Sep 28, 2026 at 10:24:02AM +0100, Sebastian Andrzej Siewior wrote: > could you please do > (in_nmi() | hardirq_count()) == HARDIRQ_OFFSET) > instead? This will merge NMI check into the hardirq check, dropping one > conditional jump away. > Hello Sebastian, Good catch. With GCC it removes one conditional branch on x86-64, arm64 and arm32. On x86-64 it also uses three fewer instructions. I will send this tweaked version soon. Thanks for the review! Karl