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 561CF2A1BB; Thu, 24 Jul 2025 05:18:15 +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=1753334295; cv=none; b=oJ31h0ZL8om6imCeydBgcdffLutdugN1FzXjHJbipGODA8vevdk7uoZmbhXtWZbNo3t8sKbXsuABWqJU9znr1/dgr36CrnZep4rhA9owxducBmwx8p+vufdX8baeUGFQzxt0mnEIZlI0Xxew0Z2z3Ys6mKeM9NsbFqWcBltEUSc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753334295; c=relaxed/simple; bh=GbrUnm5CwA+Iub1SElDV2vDitfy2uO0GIXx02fQSgLo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=rzjP23xYvCIeG3m2cESkclq2oZr316moj2L8Wfg3LoPzN7/crndm8cSu6A/ehWyRbLMnXSV7+QXUGIJdXtDfn18UAQMvPyytFO0FMT8dL2kt27BXVeirTC9kZXxamqrL8gSWcmk1ylXCHpX6WX0oQUSHRf+fz1gSIcJQTE+ESg8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=q9FOX7LB; 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="q9FOX7LB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3738DC4CEED; Thu, 24 Jul 2025 05:18:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1753334295; bh=GbrUnm5CwA+Iub1SElDV2vDitfy2uO0GIXx02fQSgLo=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=q9FOX7LBQRReG/YAp1CozHoffOFUbgQ2usok82trvfgot4I9n2YHJEPR3AGQXIaHN McsvU+DdcKDwmWJpYiSB+mTweaqw4XCjGB6/SrbQRobArkB05wbpyRZegFFvNd1AoO EpYxGgIqoTVvRuRJaFqgdvLHx1TOhmcxhDYydbeHX7AiTnSD+b1mexJtZUNiSR1Lm0 ohMvHZXd62SQ1Mo7vAs3x+qylJaXovujBO6P5rGLbHZ+M+WVkQh15VbDUk8zLkifxo N85MDlXS37Cp+YmowXyFH44Re/vweksLYPvsW9xrutpjiMxDhwT77tigXZ+PorJMN+ TCDCbCagdPgCQ== Message-ID: Date: Thu, 24 Jul 2025 07:18:10 +0200 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] genirq: add support for warning on long-running IRQ handlers To: Wladislav Wiebe , tglx@linutronix.de, corbet@lwn.net, jirislaby@kernel.org Cc: akpm@linux-foundation.org, paulmck@kernel.org, rostedt@goodmis.org, Neeraj.Upadhyay@amd.com, david@redhat.com, bp@alien8.de, arnd@arndb.de, fvdl@google.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, peterz@infradead.org References: <20250723182836.1177-1-wladislav.wiebe@nokia.com> Content-Language: en-US From: Jiri Slaby Autocrypt: addr=jirislaby@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 23. 07. 25, 20:28, Wladislav Wiebe wrote: > Introduce a mechanism to detect and warn about prolonged IRQ handlers. > With a new command-line parameter (irqhandler.duration_warn_us=), > users can configure the duration threshold in microseconds when a warning > in such format should be emitted: > > "[CPU14] long duration of IRQ[159:bad_irq_handler [long_irq]], took: 1330 us" > > The implementation uses local_clock() to measure the execution duration of the > generic IRQ per-CPU event handler. ...> +static inline void irqhandler_duration_check(u64 ts_start, unsigned int irq, > + const struct irqaction *action) > +{ > + /* Approx. conversion to microseconds */ > + u64 delta_us = (local_clock() - ts_start) >> 10; Is this a microoptimization -- have you measured what speedup does it bring? IOW is it worth it instead of cleaner "/ NSEC_PER_USEC"? Or instead, you could store the diff in irqhandler_duration_threshold_ns (mind that "_ns") and avoid the shift and div completely. And what about the wrap? Don't you need abs_diff()? thanks, -- js suse labs