From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.ilvokhin.com (mail.ilvokhin.com [178.62.254.231]) (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 976732DF132 for ; Wed, 25 Feb 2026 17:22:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=178.62.254.231 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772040134; cv=none; b=i76hfETUZofEeyJATC1Xj3wGqjhhIF2MXpi+zKBRx2x7C+kgTSS5SFQLqvRVJUIqIwD4eApW3MXsrXu71tAL4xLCtVF3cKZG20ZIKkJHsK42AgsIhed+wEiK+YZhYRqejjsaPZGqPL9NRAXO7ASN5BqmPE+UadCWZObGqEFep+A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772040134; c=relaxed/simple; bh=1VFbiGqpsmiOmEUII4sfifOeLis8K35Bcg9t4RG392o=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=OkCpRI6r3NN+qxNfuJQis2p9ux0cqZZiYDCQG7ZFnkOt5S+49ysLcrH3wz0DjmCM2v8qpOFE9KGrna7TdOtVHeP8/B1B6ikB4AbVEv08yk0QCrWXS08zJf8ZHytW9St50RICUv1E+cGD6sFhIGsvCw6mv/Kksk0z6j6jeeAoVms= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=ilvokhin.com; spf=pass smtp.mailfrom=ilvokhin.com; dkim=pass (1024-bit key) header.d=ilvokhin.com header.i=@ilvokhin.com header.b=BVqDfc3T; arc=none smtp.client-ip=178.62.254.231 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=ilvokhin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ilvokhin.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ilvokhin.com header.i=@ilvokhin.com header.b="BVqDfc3T" Received: from shell.ilvokhin.com (shell.ilvokhin.com [138.68.190.75]) (Authenticated sender: d@ilvokhin.com) by mail.ilvokhin.com (Postfix) with ESMTPSA id C1D1DB2C3F; Wed, 25 Feb 2026 17:22:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ilvokhin.com; s=mail; t=1772040130; bh=zJB/iK4EL0rFcZsVG/7/eC1TYDw4TYaJp+fMSI8Wptc=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=BVqDfc3TLgRTuUw3bso/q3GkJUezxD3pQ9i2RYUv7EiG2RHRnu1azzpqQTUY5XvCD UmdqnFZdudx0WHQJueLjxcv+OgQ1ODhfLBusMYYQ3/z3c8YRBnbVYF2adQlXtP2jom aRs+lKRu0whTIepOXIZMSqygrYr86YHqXwNwNI2E= Date: Wed, 25 Feb 2026 17:22:06 +0000 From: Dmitry Ilvokhin To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH v2] x86/irq: Optimize interrupts decimals printing Message-ID: References: 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=us-ascii Content-Disposition: inline In-Reply-To: I would like to follow up on this patch with additional data from production deployment. We have rolled out this change to a subset of the Meta fleet. On each machine, dynolog [1] periodically reads /proc/interrupts to collect per-CPU interrupt statistics, so this path executes frequently across the fleet. After deploying the patch, we measured the reduction in CPU cycles spent in the /proc/interrupts read path on machines with different virtual core counts. vCores Cycle reduction ------ --------------- 36 -18.9% 72 -25.5% 252 -34.7% As expected, the benefit increases with higher core counts, since the formatting work scales with the number of CPUs. We have not observed any functional regressions or changes in the output format. Existing userspace parsers continue to work without modification. Please let me know if there are any concerns or if additional data would be helpful. [1]: https://github.com/facebookincubator/dynolog