samples: add a skeleton of a sample DAMON module for working set size estimation

Patch series "mm/damon: add sample modules".

Implement a proactive cold memory regions reclaiming logic of prcl sample
module using DAMOS.  The logic treats memory regions that not accessed at
all for five or more seconds as cold, and reclaim those as soon as found.

This patch (of 5):

Add a skeleton for a sample DAMON static module that can be used for
estimating working set size of a given process.  Note that it is a static
module since DAMON is not exporting symbols to loadable modules for now.
It exposes two module parameters, namely 'pid' and 'enable'.  'pid' will
specify the process that the module will estimate the working set size of.
'enable' will receive whether to start or stop the estimation.  Because
this is just a skeleton, the parameters do nothing, though.  The
functionalities will be implemented by following commits.

Link: https://lkml.kernel.org/r/20241210215030.85675-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20241210215030.85675-2-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/MAINTAINERS b/MAINTAINERS
index 30cbc3d44cd53e6b1a81d56161004d7ab825d7a9..46e4ccf18c994c4e27a27f3bb46cd84bc6e7dd0f 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6330,6 +6330,7 @@ F:        Documentation/mm/damon/
 F:     include/linux/damon.h
 F:     include/trace/events/damon.h
 F:     mm/damon/
+F:     samples/damon/
 F:     tools/testing/selftests/damon/
 
 DAVICOM FAST ETHERNET (DMFE) NETWORK DRIVER

diff --git a/samples/Kconfig b/samples/Kconfig
index b288d9991d27ae9f064e388fb691ff0d6f0c2ff8..8d5a36f0e5d6b63b345aab2d4ccb18c5424fd48b 100644 (file)
--- a/samples/Kconfig
+++ b/samples/Kconfig
@@ -293,6 +293,8 @@ config SAMPLE_CGROUP
 
 source "samples/rust/Kconfig"
 
+source "samples/damon/Kconfig"
+
 endif # SAMPLES
 
 config HAVE_SAMPLE_FTRACE_DIRECT

diff --git a/samples/Makefile b/samples/Makefile
index b85fa64390c515e14224e07918688b04eabb54b3..726bb5293486043e3dfcc42285e876618b7ac43b 100644 (file)
--- a/samples/Makefile
+++ b/samples/Makefile
@@ -39,3 +39,4 @@ obj-$(CONFIG_SAMPLE_KMEMLEAK)         += kmemleak/
 obj-$(CONFIG_SAMPLE_CORESIGHT_SYSCFG)  += coresight/
 obj-$(CONFIG_SAMPLE_FPROBE)            += fprobe/
 obj-$(CONFIG_SAMPLES_RUST)             += rust/
+obj-$(CONFIG_SAMPLE_DAMON_WSSE)                += damon/

diff --git a/samples/damon/Kconfig b/samples/damon/Kconfig
new file mode 100644 (file)
index 0000000..b799e01
--- /dev/null
+++ b/samples/damon/Kconfig
@@ -0,0 +1,17 @@
+# SPDX-License-Identifier: GPL-2.0
+
+menu "DAMON Samples"
+
+config SAMPLE_DAMON_WSSE
+       bool "DAMON sameple module for working set size estimation"
+       depends on DAMON && DAMON_VADDR
+       help
+         This builds DAMON sample module for working set size estimation.
+
+         The module receives a pid, monitor access to the virtual address
+         space of the process, estimate working set size of the process, and
+         repeatedly prints the size on the kernel log.
+
+         If unsure, say N.
+
+endmenu

diff --git a/samples/damon/Makefile b/samples/damon/Makefile
new file mode 100644 (file)
index 0000000..ccbe93d
--- /dev/null
+++ b/samples/damon/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0
+
+obj-$(CONFIG_SAMPLE_DAMON_WSSE) += wsse.o

diff --git a/samples/damon/wsse.c b/samples/damon/wsse.c
new file mode 100644 (file)
index 0000000..7f2cb76
--- /dev/null
+++ b/samples/damon/wsse.c
@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * working set size estimation: monitor access pattern of given process and
+ * print estimated working set size (total size of regions that showing some
+ * access).
+ */
+
+#define pr_fmt(fmt) "damon_sample_wsse: " fmt
+
+#include <linux/damon.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+static int target_pid __read_mostly;
+module_param(target_pid, int, 0600);
+
+static int damon_sample_wsse_enable_store(
+               const char *val, const struct kernel_param *kp);
+
+static const struct kernel_param_ops enable_param_ops = {
+       .set = damon_sample_wsse_enable_store,
+       .get = param_get_bool,
+};
+
+static bool enable __read_mostly;
+module_param_cb(enable, &enable_param_ops, &enable, 0600);
+MODULE_PARM_DESC(enable, "Enable or disable DAMON_SAMPLE_WSSE");
+
+static int damon_sample_wsse_start(void)
+{
+       pr_info("start\n");
+       return 0;
+}
+
+static void damon_sample_wsse_stop(void)
+{
+       pr_info("stop\n");
+}
+
+static int damon_sample_wsse_enable_store(
+               const char *val, const struct kernel_param *kp)
+{
+       bool enabled = enable;
+       int err;
+
+       err = kstrtobool(val, &enable);
+       if (err)
+               return err;
+
+       if (enable == enabled)
+               return 0;
+
+       if (enable)
+               return damon_sample_wsse_start();
+       damon_sample_wsse_stop();
+       return 0;
+}
+
+static int __init damon_sample_wsse_init(void)
+{
+       return 0;
+}
+
+module_init(damon_sample_wsse_init);