linux-kernel - [RFC v7 08/10] tools/damon/record: Support physical memory monitoring

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Message-ID: <20200818072501.30396-9-sjpark@amazon.com>
Date:   Tue, 18 Aug 2020 09:24:59 +0200
From:   SeongJae Park <sjpark@...zon.com>
To:     <akpm@...ux-foundation.org>
CC:     SeongJae Park <sjpark@...zon.de>, <Jonathan.Cameron@...wei.com>,
        <aarcange@...hat.com>, <acme@...nel.org>,
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Subject: [RFC v7 08/10] tools/damon/record: Support physical memory monitoring

From: SeongJae Park <sjpark@...zon.de>

This commit allows users to record the data accesses on physical memory
address space by passing 'paddr' as target to 'damo-record'.  If the
init regions are given, the regions will be monitored.  Else, it will
monitor biggest conitguous 'System RAM' region in '/proc/iomem' and
monitor the region.

Signed-off-by: SeongJae Park <sjpark@...zon.de>
---
 tools/damon/_damon.py |  2 ++
 tools/damon/record.py | 29 ++++++++++++++++++++++++++++-
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/tools/damon/_damon.py b/tools/damon/_damon.py
index a22ec3777c16..6ff278117e84 100644
--- a/tools/damon/_damon.py
+++ b/tools/damon/_damon.py
@@ -27,6 +27,8 @@ def set_target(tid, init_regions=[]):
     if not os.path.exists(debugfs_init_regions):
         return 0
 
+    if tid == 'paddr':
+        tid = 42
     string = ' '.join(['%s %d %d' % (tid, r[0], r[1]) for r in init_regions])
     return subprocess.call('echo "%s" > %s' % (string, debugfs_init_regions),
             shell=True, executable='/bin/bash')
diff --git a/tools/damon/record.py b/tools/damon/record.py
index 11fd54001472..6fd0b59c73e0 100644
--- a/tools/damon/record.py
+++ b/tools/damon/record.py
@@ -101,6 +101,29 @@ def set_argparser(parser):
     parser.add_argument('-o', '--out', metavar='<file path>', type=str,
             default='damon.data', help='output file path')
 
+def default_paddr_region():
+    "Largest System RAM region becomes the default"
+    ret = []
+    with open('/proc/iomem', 'r') as f:
+        # example of the line: '100000000-42b201fff : System RAM'
+        for line in f:
+            fields = line.split(':')
+            if len(fields) != 2:
+                continue
+            name = fields[1].strip()
+            if name != 'System RAM':
+                continue
+            addrs = fields[0].split('-')
+            if len(addrs) != 2:
+                continue
+            start = int(addrs[0], 16)
+            end = int(addrs[1], 16)
+
+            sz_region = end - start
+            if not ret or sz_region > (ret[1] - ret[0]):
+                ret = [start, end]
+    return ret
+
 def main(args=None):
     global orig_attrs
     if not args:
@@ -122,7 +145,11 @@ def main(args=None):
     target = args.target
 
     target_fields = target.split()
-    if not subprocess.call('which %s &> /dev/null' % target_fields[0],
+    if target == 'paddr':   # physical memory address space
+        if not init_regions:
+            init_regions = [default_paddr_region()]
+        do_record(target, False, init_regions, new_attrs, orig_attrs, pidfd)
+    elif not subprocess.call('which %s &> /dev/null' % target_fields[0],
             shell=True, executable='/bin/bash'):
         do_record(target, True, init_regions, new_attrs, orig_attrs, pidfd)
     else:
-- 
2.17.1