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From: SeongJae Park <sjpark@amazon.com>
To: <akpm@linux-foundation.org>
Cc: SeongJae Park <sjpark@amazon.de>, <Jonathan.Cameron@Huawei.com>,
	<aarcange@redhat.com>, <acme@kernel.org>,
	<alexander.shishkin@linux.intel.com>, <amit@kernel.org>,
	<benh@kernel.crashing.org>, <brendan.d.gregg@gmail.com>,
	<brendanhiggins@google.com>, <cai@lca.pw>,
	<colin.king@canonical.com>, <corbet@lwn.net>, <dwmw@amazon.com>,
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	<kirill@shutemov.name>, <mark.rutland@arm.com>, <mgorman@suse.de>,
	<minchan@kernel.org>, <mingo@redhat.com>, <namhyung@kernel.org>,
	<peterz@infradead.org>, <rdunlap@infradead.org>,
	<riel@surriel.com>, <rientjes@google.com>, <rostedt@goodmis.org>,
	<sblbir@amazon.com>, <shakeelb@google.com>, <shuah@kernel.org>,
	<sj38.park@gmail.com>, <snu@amazon.de>, <vbabka@suse.cz>,
	<vdavydov.dev@gmail.com>, <yang.shi@linux.alibaba.com>,
	<ying.huang@intel.com>, <david@redhat.com>,
	<linux-damon@amazon.com>, <linux-mm@kvack.org>,
	<linux-doc@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: [PATCH v15 06/14] mm/damon: Implement callbacks
Date: Mon, 8 Jun 2020 13:40:39 +0200
Message-ID: <20200608114047.26589-7-sjpark@amazon.com> (raw)
In-Reply-To: <20200608114047.26589-1-sjpark@amazon.com>

From: SeongJae Park <sjpark@amazon.de>

This commit implements callbacks for DAMON.  Using this, DAMON users can
install their callbacks for each step of the access monitoring so that
they can do something interesting with the monitored access patterns
online.  For example, callbacks can report the monitored patterns to
users or do some access pattern based memory management such as
proactive reclamations or access pattern based THP promotions/demotions
decision makings.

Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reviewed-by: Leonard Foerster <foersleo@amazon.de>
---
 include/linux/damon.h | 13 +++++++++++++
 mm/damon.c            |  4 ++++
 2 files changed, 17 insertions(+)

diff --git a/include/linux/damon.h b/include/linux/damon.h
index 5afcb2bb7f77..12536d9d2f74 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -80,6 +80,15 @@ struct damon_task {
  * @kdamond_lock.  Accesses to other fields must be protected by themselves.
  *
  * @tasks_list:		Head of monitoring target tasks (&damon_task) list.
+ *
+ * @sample_cb:			Called for each sampling interval.
+ * @aggregate_cb:		Called for each aggregation interval.
+ *
+ * @sample_cb and @aggregate_cb are called from @kdamond for each of the
+ * sampling intervals and aggregation intervals, respectively.  Therefore,
+ * users can safely access to the monitoring results via @tasks_list without
+ * additional protection of @kdamond_lock.  For the reason, users are
+ * recommended to use these callback for the accesses to the results.
  */
 struct damon_ctx {
 	unsigned long sample_interval;
@@ -96,6 +105,10 @@ struct damon_ctx {
 	struct mutex kdamond_lock;
 
 	struct list_head tasks_list;	/* 'damon_task' objects */
+
+	/* callbacks */
+	void (*sample_cb)(struct damon_ctx *context);
+	void (*aggregate_cb)(struct damon_ctx *context);
 };
 
 int damon_set_pids(struct damon_ctx *ctx, int *pids, ssize_t nr_pids);
diff --git a/mm/damon.c b/mm/damon.c
index 778f4d87042d..1978ec4114bf 100644
--- a/mm/damon.c
+++ b/mm/damon.c
@@ -880,6 +880,8 @@ static int kdamond_fn(void *data)
 	kdamond_init_regions(ctx);
 	while (!kdamond_need_stop(ctx)) {
 		kdamond_prepare_access_checks(ctx);
+		if (ctx->sample_cb)
+			ctx->sample_cb(ctx);
 
 		usleep_range(ctx->sample_interval, ctx->sample_interval + 1);
 
@@ -887,6 +889,8 @@ static int kdamond_fn(void *data)
 
 		if (kdamond_aggregate_interval_passed(ctx)) {
 			kdamond_merge_regions(ctx, max_nr_accesses / 10);
+			if (ctx->aggregate_cb)
+				ctx->aggregate_cb(ctx);
 			kdamond_reset_aggregated(ctx);
 			kdamond_split_regions(ctx);
 		}
-- 
2.17.1



  parent reply index

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-08 11:40 [PATCH v15 00/14] Introduce Data Access MONitor (DAMON) SeongJae Park
2020-06-08 11:40 ` [PATCH v15 01/14] mm/page_ext: Export lookup_page_ext() to GPL modules SeongJae Park
2020-06-08 11:53   ` David Hildenbrand
2020-06-08 11:56     ` SeongJae Park
2020-06-08 15:49     ` Christoph Hellwig
2020-06-08 17:48       ` SeongJae Park
2020-06-08 18:15       ` David Hildenbrand
2020-06-10 20:13   ` vrd
2020-06-08 11:40 ` [PATCH v15 02/14] mm: Introduce Data Access MONitor (DAMON) SeongJae Park
2020-06-08 11:40 ` [PATCH v15 03/14] mm/damon: Implement region based sampling SeongJae Park
2020-06-10 20:36   ` vrd
2020-06-11  7:21     ` SeongJae Park
2020-06-08 11:40 ` [PATCH v15 04/14] mm/damon: Adaptively adjust regions SeongJae Park
2020-06-10 10:13   ` SeongJae Park
2020-06-08 11:40 ` [PATCH v15 05/14] mm/damon: Apply dynamic memory mapping changes SeongJae Park
2020-06-08 11:40 ` SeongJae Park [this message]
2020-06-08 11:40 ` [PATCH v15 07/14] mm/damon: Implement access pattern recording SeongJae Park
2020-06-08 11:40 ` [PATCH v15 08/14] mm/damon: Add debugfs interface SeongJae Park
2020-06-08 11:40 ` [PATCH v15 09/14] mm/damon: Add tracepoints SeongJae Park
2020-06-08 11:40 ` [PATCH v15 10/14] tools: Add a minimal user-space tool for DAMON SeongJae Park
2020-06-08 11:40 ` [PATCH v15 11/14] Documentation/admin-guide/mm: Add a document " SeongJae Park
2020-06-08 11:40 ` [PATCH v15 12/14] mm/damon: Add kunit tests SeongJae Park
2020-06-08 11:40 ` [PATCH v15 13/14] mm/damon: Add user space selftests SeongJae Park
2020-06-08 11:40 ` [PATCH v15 14/14] MAINTAINERS: Update for DAMON SeongJae Park

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