The quilt patch titled
Subject: mm: add bdi_set_strict_limit() function
has been removed from the -mm tree. Its filename was
mm-add-bdi_set_strict_limit-function.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Stefan Roesch <shr@xxxxxxxxxxxx>
Subject: mm: add bdi_set_strict_limit() function
Date: Fri, 18 Nov 2022 16:51:56 -0800
Patch series "mm/block: add bdi sysfs knobs", v4.
At meta network block devices (nbd) are used to implement remote block
storage. In testing and during production it has been observed that these
network block devices can consume a huge portion of the dirty writeback
cache and writeback can take a considerable time.
To be able to give stricter limits, I'm proposing the following changes:
1) introduce strictlimit knob
Currently the max_ratio knob exists to limit the dirty_memory. However
this knob only applies once (dirty_ratio + dirty_background_ratio) / 2
has been reached.
With the BDI_CAP_STRICTLIMIT flag, the max_ratio can be applied without
reaching that limit. This change exposes that knob.
This knob can also be useful for NFS, fuse filesystems and USB devices.
2) Use part of 1000000 internal calculation
The max_ratio is based on percentage. With the current machine sizes
percentage values can be very high (1% of a 256GB main memory is already
2.5GB). This change uses part of 1000000 instead of percentages for the
internal calculations.
3) Introduce two new sysfs knobs: min_bytes and max_bytes.
Currently all calculations are based on ratio, but for a user it often
more convenient to specify a limit in bytes. The new knobs will not
store bytes values, instead they will translate the byte value to a
corresponding ratio. As the internal values are now part of 1000, the
ratio is closer to the specified value. However the value should be more
seen as an approximation as it can fluctuate over time.
3) Introduce two new sysfs knobs: min_ratio_fine and max_ratio_fine.
The granularity for the existing sysfs bdi knobs min_ratio and max_ratio
is based on percentage values. The new sysfs bdi knobs min_ratio_fine
and max_ratio_fine allow to specify the ratio as part of 1 million.
This patch (of 20):
This adds the bdi_set_strict_limit function to be able to set/unset the
BDI_CAP_STRICTLIMIT flag.
Link: https://lkml.kernel.org/r/20221119005215.3052436-1-shr@xxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20221119005215.3052436-2-shr@xxxxxxxxxxxx
Signed-off-by: Stefan Roesch <shr@xxxxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Chris Mason <clm@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/backing-dev.h | 1 +
mm/page-writeback.c | 15 +++++++++++++++
2 files changed, 16 insertions(+)
--- a/include/linux/backing-dev.h~mm-add-bdi_set_strict_limit-function
+++ a/include/linux/backing-dev.h
@@ -104,6 +104,7 @@ static inline unsigned long wb_stat_erro
int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
+int bdi_set_strict_limit(struct backing_dev_info *bdi, unsigned int strict_limit);
/*
* Flags in backing_dev_info::capability
--- a/mm/page-writeback.c~mm-add-bdi_set_strict_limit-function
+++ a/mm/page-writeback.c
@@ -698,6 +698,21 @@ int bdi_set_max_ratio(struct backing_dev
}
EXPORT_SYMBOL(bdi_set_max_ratio);
+int bdi_set_strict_limit(struct backing_dev_info *bdi, unsigned int strict_limit)
+{
+ if (strict_limit > 1)
+ return -EINVAL;
+
+ spin_lock_bh(&bdi_lock);
+ if (strict_limit)
+ bdi->capabilities |= BDI_CAP_STRICTLIMIT;
+ else
+ bdi->capabilities &= ~BDI_CAP_STRICTLIMIT;
+ spin_unlock_bh(&bdi_lock);
+
+ return 0;
+}
+
static unsigned long dirty_freerun_ceiling(unsigned long thresh,
unsigned long bg_thresh)
{
_
Patches currently in -mm which might be from shr@xxxxxxxxxxxx are
