linux-kernel - [PATCH 1/2] amd-pstate: Set min_perf to nominal

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Message-ID: <20241021101836.9047-2-gautham.shenoy@amd.com>
Date: Mon, 21 Oct 2024 15:48:35 +0530
From: "Gautham R. Shenoy" <gautham.shenoy@....com>
To: Mario Limonciello <mario.limonciello@....com>, Perry Yuan
	<perry.yuan@....com>, Huang Rui <ray.huang@....com>, Dhananjay Ugwekar
	<Dhananjay.Ugwekar@....com>, Swapnil Sapkal <swapnil.sapkal@....com>, "Rafael
 J . Wysocki" <rafael@...nel.org>, Viresh Kumar <viresh.kumar@...aro.org>
CC: <linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>, "Gautham R.
 Shenoy" <gautham.shenoy@....com>
Subject: [PATCH 1/2] amd-pstate: Set min_perf to nominal_perf for active mode performance gov

The amd-pstate driver sets CPPC_REQ.min_perf to CPPC_REQ.max_perf when
in active mode with performance governor. Typically CPPC_REQ.max_perf
is set to CPPC.highest_perf. This causes frequency throttling on
power-limited platforms which causes performance regressions on
certain classes of workloads.

Hence, set the CPPC_REQ.min_perf to the CPPC.nominal_perf or
CPPC_REQ.max_perf, whichever is lower of the two.

Fixes: ffa5096a7c33 ("cpufreq: amd-pstate: implement Pstate EPP support for the AMD processors")
Signed-off-by: Gautham R. Shenoy <gautham.shenoy@....com>
---
 drivers/cpufreq/amd-pstate.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 6f6d961879cc..23349f50c83e 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -1535,7 +1535,7 @@ static int amd_pstate_epp_update_limit(struct cpufreq_policy *policy)
 	value = READ_ONCE(cpudata->cppc_req_cached);
 
 	if (cpudata->policy == CPUFREQ_POLICY_PERFORMANCE)
-		min_perf = max_perf;
+		min_perf = min(cpudata->nominal_perf, max_perf);
 
 	/* Initial min/max values for CPPC Performance Controls Register */
 	value &= ~AMD_CPPC_MIN_PERF(~0L);
-- 
2.34.1