linux-kernel - [RFC PATCH v2 2/5] hq-spinlock: proc tunables and debug stats

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20251206062106.2109014-3-stepanov.anatoly@huawei.com>
Date: Sat, 6 Dec 2025 14:21:03 +0800
From: Anatoly Stepanov <stepanov.anatoly@...wei.com>
To: <peterz@...radead.org>, <boqun.feng@...il.com>, <longman@...hat.com>,
	<catalin.marinas@....com>, <will@...nel.org>, <mingo@...hat.com>,
	<bp@...en8.de>, <dave.hansen@...ux.intel.com>, <x86@...nel.org>,
	<hpa@...or.com>, <arnd@...db.de>, <dvhart@...radead.org>,
	<dave@...olabs.net>, <andrealmeid@...lia.com>
CC: <linux-kernel@...r.kernel.org>, <linux-arch@...r.kernel.org>,
	<guohanjun@...wei.com>, <wangkefeng.wang@...wei.com>,
	<weiyongjun1@...wei.com>, <yusongping@...wei.com>, <leijitang@...wei.com>,
	<artem.kuzin@...wei.com>, <fedorov.nikita@...artners.com>,
	<kang.sun@...wei.com>, Anatoly Stepanov <stepanov.anatoly@...wei.com>
Subject: [RFC PATCH v2 2/5] hq-spinlock: proc tunables and debug stats

- tunable for handoff threshold
- tunable for lock-mode switching
- debug stats

Signed-off-by: Anatoly Stepanov <stepanov.anatoly@...wei.com>

Co-authored-by: Stepanov Anatoly <stepanov.anatoly@...wei.com>
Co-authored-by: Fedorov Nikita <fedorov.nikita@...artners.com>
---
 kernel/locking/hqlock_proc.h | 88 ++++++++++++++++++++++++++++++++++++
 1 file changed, 88 insertions(+)
 create mode 100644 kernel/locking/hqlock_proc.h

diff --git a/kernel/locking/hqlock_proc.h b/kernel/locking/hqlock_proc.h
new file mode 100644
index 000000000..5e9ed0446
--- /dev/null
+++ b/kernel/locking/hqlock_proc.h
@@ -0,0 +1,88 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _GEN_HQ_SPINLOCK_SLOWPATH
+#error "Do not include this file!"
+#endif
+
+#include <linux/sysctl.h>
+
+/*
+ * Local handoffs threshold to maintain global fairness,
+ * perform remote handoff if it's reached
+ */
+unsigned long hqlock_fairness_threshold = 1000;
+
+/*
+ * Minimal amount of handoffs in LOCK_MODE_QSPINLOCK
+ * to enable NUMA-awareness
+ */
+unsigned long hqlock_general_handoffs_turn_numa = 50;
+
+static unsigned long long_zero;
+static unsigned long long_max = LONG_MAX;
+
+static const struct ctl_table hqlock_settings[] = {
+	{
+		.procname		= "hqlock_fairness_threshold",
+		.data			= &hqlock_fairness_threshold,
+		.maxlen			= sizeof(hqlock_fairness_threshold),
+		.mode			= 0644,
+		.proc_handler	= proc_doulongvec_minmax
+	},
+	{
+		.procname		= "hqlock_general_handoffs_turn_numa",
+		.data			= &hqlock_general_handoffs_turn_numa,
+		.maxlen			= sizeof(hqlock_general_handoffs_turn_numa),
+		.mode			= 0644,
+		.proc_handler	= proc_doulongvec_minmax,
+		.extra1		= &long_zero,
+		.extra2		= &long_max,
+	},
+};
+static int __init init_numa_spinlock_sysctl(void)
+{
+	if (!register_sysctl("kernel", hqlock_settings))
+		return -EINVAL;
+	return 0;
+}
+core_initcall(init_numa_spinlock_sysctl);
+
+
+#ifdef CONFIG_HQSPINLOCKS_DEBUG
+static int max_buckets_in_use;
+static int max_general_handoffs;
+static atomic_t cur_buckets_in_use = ATOMIC_INIT(0);
+
+static int print_hqlock_stats(struct seq_file *file, void *v)
+{
+	seq_printf(file, "Max dynamic metada in use after previous print: %d\n",
+		   READ_ONCE(max_buckets_in_use));
+	WRITE_ONCE(max_buckets_in_use, 0);
+
+	seq_printf(file, "Max MCS handoffs after previous print: %d\n",
+		   READ_ONCE(max_general_handoffs));
+	WRITE_ONCE(max_general_handoffs, 0);
+
+	return 0;
+}
+
+
+static int stats_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, print_hqlock_stats, NULL);
+}
+
+static const struct proc_ops stats_ops = {
+	.proc_open  = stats_open,
+	.proc_read  = seq_read,
+	.proc_lseek = seq_lseek,
+};
+
+static int __init stats_init(void)
+{
+	proc_create("hqlock_stats", 0444, NULL, &stats_ops);
+	return 0;
+}
+
+core_initcall(stats_init);
+
+#endif // HQSPINLOCKS_DEBUG
-- 
2.34.1