From nobody Mon Nov 25 05:11:16 2024 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 49877207A0A for ; Tue, 29 Oct 2024 21:38:17 +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=1730237899; cv=none; b=JR2wBeBgMTCLIImqE47NqVS0ss9bkbjjHFv9kwAZCV/GGGTk+voqQuRA16wzIdSfKg1fBCM+BrUgZX32eHv9g/miw5ia1wZF4zosm13cAgK4IPN/0pGSCXJKx2StabAzZ6I8iy7f1k3Dij1TthH2XA5bxggQbXZ2upClJGBBAv0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730237899; c=relaxed/simple; bh=+wJ5KWpgT+2Otb1SXgnm+ECduxv9o6ciNoEgRwIi6/Y=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=Uthv1k3Tje7f1+VaZYgPPHNJ3cq6DTj1gSZssyClyCFSJ4Lal3mRjrGay6rr2CVi3Hl2IBzDaxvIQOh2viG4/Ixwvw5qGvXSKey6iHJmPCr8+8nqowWH7UbUcxmYs/UIu4ziHCKyufBAs1nEWphWt4Ij6fgpy3u4j2xlUfWjtt8= 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=f2Sgxykr; 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="f2Sgxykr" DKIM-Signature: v=1; a=rsa-sha256; d=email-od.com;i=@email-od.com;s=dkim; c=relaxed/relaxed; q=dns/txt; t=1730237897; x=1732829897; 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=jizTLtrLMmCt7wE/5ipTFTDD8VO6t5SHcJxMFWKWNrM=; b=f2SgxykrbxFqbq5iQHCsyS2CAJXZdA3le9O25zVGTgKuC/RezP54Ioj9Q57lByefLkCCBAL0aA1FihTPQc4OS+4xGAU2H3yey6Tecdec90rOhUh++CXA1dBacQzEZUk7RvZhrEjrRVthW+vwYNabzvGscUQgEGLaBT+YgKcr/I4= X-Thread-Info: NDUwNC4xMi4zZmU2ZjAwMDBmMzg1OTAubGludXgta2VybmVsPXZnZXIua2VybmVsLm9yZw== 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 CE3152CE04B1; Tue, 29 Oct 2024 17:37:54 -0400 (EDT) From: "Nabil S. Alramli" To: stable@vger.kernel.org Cc: nalramli@fastly.com, jdamato@fastly.com, khubert@fastly.com, mario.limonciello@amd.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: [PATCH 6.1.y v2] cpufreq: amd-pstate: Enable CPU boost in passive and guided modes Date: Tue, 29 Oct 2024 17:36:43 -0400 Message-Id: <20241029213643.2966723-1-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 Content-Type: text/plain; charset="utf-8" CPU frequency cannot be boosted when using the amd_pstate driver in passive or guided mode. On a host that has an AMD EPYC 7662 processor, while running with amd-pstate configured for passive mode on full CPU load, the processor only reaches 2.0 GHz. On later kernels the CPU can reach 3.3GHz. The CPU frequency is dependent on a setting called highest_perf which is the multiplier used to compute it. The highest_perf value comes from cppc_init_perf when the driver is built-in and from pstate_init_perf when it is a loaded module. Both of these calls have the following condition: highest_perf =3D amd_get_highest_perf(); if (highest_perf > __cppc_highest_perf_) highest_perf =3D __cppc_highest_perf; Where again __cppc_highest_perf is either the return from cppc_get_perf_caps in the built-in case or AMD_CPPC_HIGHEST_PERF in the module case. Both of these functions actually return the nominal value, whereas the call to amd_get_highest_perf returns the correct boost value, so the condition tests true and highest_perf always ends up being the nominal value, therefore never having the ability to boost CPU frequency. Since amd_get_highest_perf already returns the boost value, we have eliminated this check. The issue was introduced in v6.1 via commit bedadcfb011f ("cpufreq: amd-pstate: Fix initial highest_perf value"), and exists in stable v6.1 kernels. This has been fixed in v6.6.y and newer but due to refactoring that change isn't feasible to bring back to v6.1.y. Thus, v6.1 kernels are affected by this significant performance issue, and cannot be easily remediated. Signed-off-by: Nabil S. Alramli Reviewed-by: Joe Damato Reviewed-by: Kyle Hubert Fixes: bedadcfb011f ("cpufreq: amd-pstate: Fix initial highest_perf value") See-also: 1ec40a175a48 ("cpufreq: amd-pstate: Enable amd-pstate preferred c= ore support") Cc: mario.limonciello@amd.com Cc: Perry.Yuan@amd.com Cc: li.meng@amd.com Cc: stable@vger.kernel.org # v6.1 Reviewed-by: Mario Limonciello --- v2: - Omit cover letter - Converted from RFC to PATCH - Expand commit message based on feedback from Mario Limonciello - Added Reviewed-by tags - No functional/code changes rfc: https://lore.kernel.org/lkml/20241025010527.491605-1-dev@nalramli.com/ --- drivers/cpufreq/amd-pstate.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c index 90dcf26f0973..c66086ae624a 100644 --- a/drivers/cpufreq/amd-pstate.c +++ b/drivers/cpufreq/amd-pstate.c @@ -102,9 +102,7 @@ static int pstate_init_perf(struct amd_cpudata *cpudata) * * CPPC entry doesn't indicate the highest performance in some ASICs. */ - highest_perf =3D amd_get_highest_perf(); - if (highest_perf > AMD_CPPC_HIGHEST_PERF(cap1)) - highest_perf =3D AMD_CPPC_HIGHEST_PERF(cap1); + highest_perf =3D max(amd_get_highest_perf(), AMD_CPPC_HIGHEST_PERF(cap1)); =20 WRITE_ONCE(cpudata->highest_perf, highest_perf); =20 @@ -124,9 +122,7 @@ static int cppc_init_perf(struct amd_cpudata *cpudata) if (ret) return ret; =20 - highest_perf =3D amd_get_highest_perf(); - if (highest_perf > cppc_perf.highest_perf) - highest_perf =3D cppc_perf.highest_perf; + highest_perf =3D max(amd_get_highest_perf(), cppc_perf.highest_perf); =20 WRITE_ONCE(cpudata->highest_perf, highest_perf); =20 --=20 2.35.1