[RFC,v4,16/20] mm: add /sys/class/bdi/<bdi>/max_ratio_fine knob

Commit Message

Stefan Roesch Nov. 19, 2022, 12:52 a.m. UTC

This adds the max_ratio_fine knob. The knob specifies the values not
based on 1 of 100, but instead 1 per million.

Signed-off-by: Stefan Roesch <[e-mail]>
---
 mm/backing-dev.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

Patch

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 3fab79061ade..94c2382367cf 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -199,6 +199,25 @@  static ssize_t max_ratio_store(struct device *dev,
 }
 BDI_SHOW(max_ratio, bdi->max_ratio / BDI_RATIO_SCALE)
 
+static ssize_t max_ratio_fine_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t count)
+{
+	struct backing_dev_info *bdi = dev_get_drvdata(dev);
+	unsigned int ratio;
+	ssize_t ret;
+
+	ret = kstrtouint(buf, 10, &ratio);
+	if (ret < 0)
+		return ret;
+
+	ret = bdi_set_max_ratio_no_scale(bdi, ratio);
+	if (!ret)
+		ret = count;
+
+	return ret;
+}
+BDI_SHOW(max_ratio_fine, bdi->max_ratio)
+
 static ssize_t min_bytes_show(struct device *dev,
 			      struct device_attribute *attr,
 			      char *buf)
@@ -297,6 +316,7 @@  static struct attribute *bdi_dev_attrs[] = {
 	&dev_attr_read_ahead_kb.attr,
 	&dev_attr_min_ratio.attr,
 	&dev_attr_max_ratio.attr,
+	&dev_attr_max_ratio_fine.attr,
 	&dev_attr_min_bytes.attr,
 	&dev_attr_max_bytes.attr,
 	&dev_attr_stable_pages_required.attr,