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From:   Leonardo Bras <leobras@redhat.com>
To:     Steffen Klassert <steffen.klassert@secunet.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        "David S. Miller" <davem@davemloft.net>,
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        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Leonardo Bras <leobras@redhat.com>,
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Cc:     linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-pci@vger.kernel.org, netdev@vger.kernel.org
Subject: [PATCH v2 2/4] sched/isolation: Improve documentation
Date:   Thu, 13 Oct 2022 15:40:27 -0300
Message-Id: <20221013184028.129486-3-leobras@redhat.com>
In-Reply-To: <20221013184028.129486-1-leobras@redhat.com>
References: <20221013184028.129486-1-leobras@redhat.com>
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Improve documentation on housekeeping types and what to expect from
housekeeping functions.

Signed-off-by: Leonardo Bras <leobras@redhat.com>
---
 include/linux/sched/isolation.h | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h
index 762701f295d1c..9333c28153a7a 100644
--- a/include/linux/sched/isolation.h
+++ b/include/linux/sched/isolation.h
@@ -7,18 +7,25 @@
 #include <linux/tick.h>
 
 enum hk_type {
-	HK_TYPE_TIMER,
-	HK_TYPE_RCU,
-	HK_TYPE_MISC,
-	HK_TYPE_SCHED,
-	HK_TYPE_TICK,
-	HK_TYPE_DOMAIN,
-	HK_TYPE_WQ,
-	HK_TYPE_MANAGED_IRQ,
-	HK_TYPE_KTHREAD,
+	HK_TYPE_TIMER,		/* Timer interrupt, watchdogs */
+	HK_TYPE_RCU,		/* RCU callbacks */
+	HK_TYPE_MISC,		/* Minor housekeeping categories */
+	HK_TYPE_SCHED,		/* Scheduling and idle load balancing */
+	HK_TYPE_TICK,		/* See isolcpus=nohz boot parameter */
+	HK_TYPE_DOMAIN,		/* See isolcpus=domain boot parameter*/
+	HK_TYPE_WQ,		/* Work Queues*/
+	HK_TYPE_MANAGED_IRQ,	/* See isolcpus=managed_irq boot parameter */
+	HK_TYPE_KTHREAD,	/* kernel threads */
 	HK_TYPE_MAX
 };
 
+/* Kernel parameters like nohz_full and isolcpus allow passing cpu numbers
+ * for disabling housekeeping types.
+ *
+ * The functions bellow work the opposite way, by referencing which cpus
+ * are able to perform the housekeeping type in parameter.
+ */
+
 #ifdef CONFIG_CPU_ISOLATION
 DECLARE_STATIC_KEY_FALSE(housekeeping_overridden);
 int housekeeping_any_cpu(enum hk_type type);
-- 
2.38.0