From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from s1-ba86.socketlabs.email-od.com (s1-ba86.socketlabs.email-od.com [142.0.186.134]) (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 AB8224409 for ; Fri, 25 Oct 2024 02:06:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=142.0.186.134 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729821983; cv=none; b=M7UT44L1aZOX4uG3MR5ghbtYo/gKJwwkjYlbYCKEI5oMet1toSrmVTXXYbQN+GPe9bVX7ccmeS2eHEpUAjPFvRdGd4jnSIlQDQBlsiWKfd7Upq7C8F2Wz5YfQMVehAj4zBjC2xk3vR0cRxw51G6111cc74JRI7xFoRiM2w//9Mc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729821983; c=relaxed/simple; bh=NO9fmOs1GXCCcZ74pAbl6f5r+b/635OX5p3kSN9dM+4=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=sfLivj5gjIu7g4rc/QjvCQb4jYHpLycRMs5UMZ2nPFxSbfOCt1yEecOqlml1ErMwdSjXZ2juYdgTAgoC1UH3cHZyput2ZVEsB+Mq2rJhoT9LI84xnerGbMoNRe3dCwlt7GDke7ZgQJs2HBz+AiYXkJj4ZFWjmDp2i88AqSnW4kY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=nalramli.com; spf=pass smtp.mailfrom=email-od.com; dkim=pass (1024-bit key) header.d=email-od.com header.i=@email-od.com header.b=wyw68e9w; arc=none smtp.client-ip=142.0.186.134 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=nalramli.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=email-od.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=email-od.com header.i=@email-od.com header.b="wyw68e9w" DKIM-Signature: v=1; a=rsa-sha256; d=email-od.com;i=@email-od.com;s=dkim; c=relaxed/relaxed; q=dns/txt; t=1729821982; x=1732413982; h=content-transfer-encoding:mime-version:references:in-reply-to:message-id:date:subject:cc:to:from:x-thread-info:subject:to:from:cc:reply-to; bh=e/0/6KmLP8IDOZiXwbbz4hIq8Tt4TKaYWZ5giDxZMgs=; b=wyw68e9wUHCwWppOlQWXNFCjNgDpxVfNNJIvMG/EfQqrvbcl7R7ywwIqRF12+dQMC3LZWt1xtDUrQMGqmGkSdRAdCAT/bbnUq8a9lsUUV3kUWtjNMjrmJs5f0PC4K62IiPNj5jpSqCaFqvc+AQhJq7hEru9bi4HHvtj7De4uI/I= X-Thread-Info: NDUwNC4xMi42YjZkZDAwMDAyZWEyZjUubGludXgta2VybmVsPXZnZXIua2VybmVsLm9yZw== x-xsSpam: eyJTY29yZSI6MCwiRGV0YWlscyI6bnVsbH0= Received: from localhost.localdomain (d4-50-191-215.clv.wideopenwest.com [50.4.215.191]) by nalramli.com (Postfix) with ESMTPS id F3BE82CE016E; Thu, 24 Oct 2024 21:05:58 -0400 (EDT) From: "Nabil S. Alramli" To: stable@vger.kernel.org Cc: nalramli@fastly.com, jdamato@fastly.com, khubert@fastly.com, Perry.Yuan@amd.com, li.meng@amd.com, ray.huang@amd.com, rafael@kernel.org, viresh.kumar@linaro.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, "Nabil S. Alramli" Subject: [RFC PATCH 6.1.y 0/1] cpufreq: amd-pstate: Enable CPU boost in passive and guided modes Date: Thu, 24 Oct 2024 21:05:26 -0400 Message-Id: <20241025010527.491605-1-dev@nalramli.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Greetings, This is a RFC for a maintenance patch to an issue in the amd_pstate drive= r where CPU frequency cannot be boosted in passive or guided modes. Without this patch, AMD machines using stable kernels are unable to get their CPU frequency boosted, which is a significant performance issue. For example, on a host that has AMD EPYC 7662 64-Core processor without this patch running at full CPU load: $ for i in $(cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_cur_freq); = \ do ni=3D$(echo "scale=3D1; $i/1000000" | bc -l); echo "$ni GHz"; done |= \ sort | uniq -c 128 2.0 GHz And with this patch: $ for i in $(cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_cur_freq); = \ do ni=3D$(echo "scale=3D1; $i/1000000" | bc -l); echo "$ni GHz"; done |= \ sort | uniq -c 128 3.3 GHz I am not sure what the correct process is for submitting patches which affect only stable trees but not the current code base, and do not apply = to the current tree. As such, I am submitting this directly to stable@, but please let me know if I should be submitting this elsewhere. The issue was introduced in v6.1 via commit bedadcfb011f ("cpufreq: amd-pstate: Fix initial highest_perf value"), and exists in stable kernel= s up until v6.6.51. In v6.6.51, a large change, commit 1ec40a175a48 ("cpufreq: amd-pstate: Enable amd-pstate preferred core support"), was introduced which significantly refactored the code. This commit cannot be ported back on i= ts own, and would require reviewing and cherry picking at least a few dozen = of commits in cpufreq, amd-pstate, ACPI, CPPC. This means kernels v6.1 up until v6.6.51 are affected by this significant performance issue, and cannot be easily remediated. Thank you for your attention and I look forward to your response in regar= ds to what the best way to proceed is for getting this important performance fix merged. Best Regards, Nabil S. Alramli (1): cpufreq: amd-pstate: Enable CPU boost in passive and guided modes drivers/cpufreq/amd-pstate.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) --=20 2.35.1