linux-kernel - [PATCH v9 8/9] x86/resctrl: Make mba_sc use total bandwidth if local is not supported

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Message-ID: <20241114001712.80315-9-tony.luck@intel.com>
Date: Wed, 13 Nov 2024 16:17:10 -0800
From: Tony Luck <tony.luck@...el.com>
To: Fenghua Yu <fenghua.yu@...el.com>,
	Reinette Chatre <reinette.chatre@...el.com>,
	Peter Newman <peternewman@...gle.com>,
	Jonathan Corbet <corbet@....net>,
	x86@...nel.org
Cc: James Morse <james.morse@....com>,
	Jamie Iles <quic_jiles@...cinc.com>,
	Babu Moger <babu.moger@....com>,
	Randy Dunlap <rdunlap@...radead.org>,
	"Shaopeng Tan (Fujitsu)" <tan.shaopeng@...itsu.com>,
	linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org,
	patches@...ts.linux.dev,
	Tony Luck <tony.luck@...el.com>
Subject: [PATCH v9 8/9] x86/resctrl: Make mba_sc use total bandwidth if local is not supported

The default input measurement to the mba_sc feedback loop for
memory bandwidth control when the user mounts with the "mba_MBps"
option has historically been the local bandwidth event.

But some systems may not support a local bandwidth event.

When local bandwidth event is not supported, check for support
of total bandwidth and use that instead.

Signed-off-by: Tony Luck <tony.luck@...el.com>
---
 arch/x86/kernel/cpu/resctrl/core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 94bf559966d6..3d1735ed8d1f 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -965,6 +965,8 @@ static __init bool get_rdt_mon_resources(void)
 
 	if (is_mbm_local_enabled())
 		mba_mbps_default_event = QOS_L3_MBM_LOCAL_EVENT_ID;
+	else if (is_mbm_total_enabled())
+		mba_mbps_default_event = QOS_L3_MBM_TOTAL_EVENT_ID;
 
 	return !rdt_get_mon_l3_config(r);
 }
-- 
2.47.0