From: Stefan Roesch shr@devkernel.io

mainline inclusion from mainline-v6.2-rc1 commit 8e9d5ead865a1a7af74a444d2f00f1ef4539bfba category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAN96I

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

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@devkernel.io Link: https://lkml.kernel.org/r/20221119005215.3052436-2-shr@devkernel.io Signed-off-by: Stefan Roesch shr@devkernel.io Cc: Jens Axboe axboe@kernel.dk Cc: Chris Mason clm@meta.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Yifan Qiao qiaoyifan4@huawei.com --- include/linux/backing-dev.h | 1 + mm/page-writeback.c | 15 +++++++++++++++ 2 files changed, 16 insertions(+)

diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index a689a21abe10..c67129defa3a 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -106,6 +106,7 @@ static inline unsigned long wb_stat_error(void)

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 diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 0d7cc65c6367..1f6104775a43 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -724,6 +724,21 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned max_ratio) } 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) {

From: Stefan Roesch shr@devkernel.io

mainline inclusion from mainline-v6.2-rc1 commit 16b837eb84e6948f92411eb32e97a05f89733ddc category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAN96I

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

This documents the new /sys/class/bdi/<bdi>/strict_limit knob.

Link: https://lkml.kernel.org/r/20221119005215.3052436-4-shr@devkernel.io Signed-off-by: Stefan Roesch shr@devkernel.io Cc: Chris Mason clm@meta.com Cc: Jens Axboe axboe@kernel.dk Signed-off-by: Andrew Morton akpm@linux-foundation.org Conflict: Documentation/ABI/testing/sysfs-class-bdi [Context differences] Signed-off-by: Yifan Qiao qiaoyifan4@huawei.com --- Documentation/ABI/testing/sysfs-class-bdi | 11 +++++++++++ 1 file changed, 11 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-class-bdi b/Documentation/ABI/testing/sysfs-class-bdi index 5402bd74ba43..9982fd0439ae 100644 --- a/Documentation/ABI/testing/sysfs-class-bdi +++ b/Documentation/ABI/testing/sysfs-class-bdi @@ -48,6 +48,17 @@ max_ratio (read-write) mount that is prone to get stuck, or a FUSE mount which cannot be trusted to play fair.

+ (read-write) +What: /sys/class/bdi/<bdi>/strict_limit +Date: October 2022 +Contact: Stefan Roesch shr@devkernel.io +Description: + Forces per-BDI checks for the share of given device in the write-back + cache even before the global background dirty limit is reached. This + is useful in situations where the global limit is much higher than + affordable for given relatively slow (or untrusted) device. Turning + strictlimit on has no visible effect if max_ratio is equal to 100%. + stable_pages_required (read-only)

If set, the backing device requires that all pages comprising a write

From: Stefan Roesch shr@devkernel.io

mainline inclusion from mainline-v6.2-rc1 commit ae82291e9ca47c3d6da6b77a00f427754aca413e category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAN96I

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

To get finer granularity for ratio calculations use part per million instead of percentiles. This is especially important if we want to automatically convert byte values to ratios. Otherwise the values that are actually used can be quite different. This is also important for machines with more main memory (1% of 256GB is already 2.5GB).

Link: https://lkml.kernel.org/r/20221119005215.3052436-5-shr@devkernel.io Signed-off-by: Stefan Roesch shr@devkernel.io Cc: Chris Mason clm@meta.com Cc: Jens Axboe axboe@kernel.dk Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Yifan Qiao qiaoyifan4@huawei.com --- include/linux/backing-dev.h | 3 +++ mm/backing-dev.c | 6 +++--- mm/page-writeback.c | 15 +++++++++------ 3 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index c67129defa3a..75a25b2145c3 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -104,6 +104,9 @@ static inline unsigned long wb_stat_error(void) #endif }

+/* BDI ratio is expressed as part per 1000000 for finer granularity. */ +#define BDI_RATIO_SCALE 10000 + 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); diff --git a/mm/backing-dev.c b/mm/backing-dev.c index d2a7b3dbfcda..b0fff65d9962 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -176,7 +176,7 @@ static ssize_t min_ratio_store(struct device *dev,

return ret; } -BDI_SHOW(min_ratio, bdi->min_ratio) +BDI_SHOW(min_ratio, bdi->min_ratio / BDI_RATIO_SCALE)

static ssize_t max_ratio_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) @@ -195,7 +195,7 @@ static ssize_t max_ratio_store(struct device *dev,

return ret; } -BDI_SHOW(max_ratio, bdi->max_ratio) +BDI_SHOW(max_ratio, bdi->max_ratio / BDI_RATIO_SCALE)

static ssize_t stable_pages_required_show(struct device *dev, struct device_attribute *attr, @@ -809,7 +809,7 @@ static int bdi_init(struct backing_dev_info *bdi)

kref_init(&bdi->refcnt); bdi->min_ratio = 0; - bdi->max_ratio = 100; + bdi->max_ratio = 100 * BDI_RATIO_SCALE; bdi->max_prop_frac = FPROP_FRAC_BASE; INIT_LIST_HEAD(&bdi->bdi_list); INIT_LIST_HEAD(&bdi->wb_list); diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 761cc9e865ae..203c7ebe84ea 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -198,7 +198,7 @@ static void wb_min_max_ratio(struct bdi_writeback *wb, min *= this_bw; min = div64_ul(min, tot_bw); } - if (max < 100) { + if (max < 100 * BDI_RATIO_SCALE) { max *= this_bw; max = div64_ul(max, tot_bw); } @@ -688,6 +688,8 @@ int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio) unsigned int delta; int ret = 0;

+ min_ratio *= BDI_RATIO_SCALE; + spin_lock_bh(&bdi_lock); if (min_ratio > bdi->max_ratio) { ret = -EINVAL; @@ -698,7 +700,7 @@ int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio) bdi->min_ratio = min_ratio; } else { delta = min_ratio - bdi->min_ratio; - if (bdi_min_ratio + delta < 100) { + if (bdi_min_ratio + delta < 100 * BDI_RATIO_SCALE) { bdi_min_ratio += delta; bdi->min_ratio = min_ratio; } else { @@ -717,6 +719,7 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned max_ratio)

if (max_ratio > 100) return -EINVAL; + max_ratio *= BDI_RATIO_SCALE;

spin_lock_bh(&bdi_lock); if (bdi->min_ratio > max_ratio) { @@ -808,15 +811,15 @@ static unsigned long __wb_calc_thresh(struct dirty_throttle_control *dtc) fprop_fraction_percpu(&dom->completions, dtc->wb_completions, &numerator, &denominator);

- wb_thresh = (thresh * (100 - bdi_min_ratio)) / 100; + wb_thresh = (thresh * (100 * BDI_RATIO_SCALE - bdi_min_ratio)) / (100 * BDI_RATIO_SCALE); wb_thresh *= numerator; wb_thresh = div64_ul(wb_thresh, denominator);

wb_min_max_ratio(dtc->wb, &wb_min_ratio, &wb_max_ratio);

- wb_thresh += (thresh * wb_min_ratio) / 100; - if (wb_thresh > (thresh * wb_max_ratio) / 100) - wb_thresh = thresh * wb_max_ratio / 100; + wb_thresh += (thresh * wb_min_ratio) / (100 * BDI_RATIO_SCALE); + if (wb_thresh > (thresh * wb_max_ratio) / (100 * BDI_RATIO_SCALE)) + wb_thresh = thresh * wb_max_ratio / (100 * BDI_RATIO_SCALE);

return wb_thresh; }

From: Stefan Roesch shr@devkernel.io

mainline inclusion from mainline-v6.2-rc1 commit efc3e6ad53ea14225b434fddca261c9a1c56c707 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAN96I

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

This splits off __bdi_set_max_ratio() from bdi_set_max_ratio(). __bdi_set_max_ratio() will also be called from bdi_set_max_bytes(), which will be introduced in the next patch.

Link: https://lkml.kernel.org/r/20221119005215.3052436-7-shr@devkernel.io Signed-off-by: Stefan Roesch shr@devkernel.io Cc: Chris Mason clm@meta.com Cc: Jens Axboe axboe@kernel.dk Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Yifan Qiao qiaoyifan4@huawei.com --- mm/page-writeback.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 8d83bd9e1c25..e0de996c1c55 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -725,14 +725,10 @@ int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio) return ret; }

-int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned max_ratio) +static int __bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio) { int ret = 0;

- if (max_ratio > 100) - return -EINVAL; - max_ratio *= BDI_RATIO_SCALE; - spin_lock_bh(&bdi_lock); if (bdi->min_ratio > max_ratio) { ret = -EINVAL; @@ -744,6 +740,14 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned max_ratio)

return ret; } + +int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio) +{ + if (max_ratio > 100) + return -EINVAL; + + return __bdi_set_max_ratio(bdi, max_ratio * BDI_RATIO_SCALE); +} EXPORT_SYMBOL(bdi_set_max_ratio);

u64 bdi_get_max_bytes(struct backing_dev_info *bdi)

From: Stefan Roesch shr@devkernel.io

mainline inclusion from mainline-v6.2-rc1 commit c56e049a5e401a177c7c9b39a3bcc973ff5cec0b category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAN96I

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

This adds the new knob max_bytes to specify a dirty memory limit for the corresponding bdi. The specified bytes value is converted to a ratio.

Link: https://lkml.kernel.org/r/20221119005215.3052436-9-shr@devkernel.io Signed-off-by: Stefan Roesch shr@devkernel.io Cc: Chris Mason clm@meta.com Cc: Jens Axboe axboe@kernel.dk Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Yifan Qiao qiaoyifan4@huawei.com --- mm/backing-dev.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+)

diff --git a/mm/backing-dev.c b/mm/backing-dev.c index b0fff65d9962..383bf0a8f90e 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -197,6 +197,34 @@ static ssize_t max_ratio_store(struct device *dev, } BDI_SHOW(max_ratio, bdi->max_ratio / BDI_RATIO_SCALE)

+static ssize_t max_bytes_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct backing_dev_info *bdi = dev_get_drvdata(dev); + + return sysfs_emit(buf, "%llu\n", bdi_get_max_bytes(bdi)); +} + +static ssize_t max_bytes_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t count) +{ + struct backing_dev_info *bdi = dev_get_drvdata(dev); + u64 bytes; + ssize_t ret; + + ret = kstrtoull(buf, 10, &bytes); + if (ret < 0) + return ret; + + ret = bdi_set_max_bytes(bdi, bytes); + if (!ret) + ret = count; + + return ret; +} +DEVICE_ATTR_RW(max_bytes); + static ssize_t stable_pages_required_show(struct device *dev, struct device_attribute *attr, char *page) @@ -239,6 +267,7 @@ 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_bytes.attr, &dev_attr_stable_pages_required.attr, &dev_attr_strict_limit.attr, NULL,

From: Stefan Roesch shr@devkernel.io

mainline inclusion from mainline-v6.2-rc1 commit 712c00d66a342a3ed375df41c3df7d3d2abad2c0 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAN96I

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

This adds a function to return the specified value for min_bytes. It converts the stored min_ratio of the bdi to the corresponding bytes value. This is an approximation as it is based on the value that is returned by global_dirty_limits(), which can change. The returned value can be different than the value when the min_bytes value was set.

Link: https://lkml.kernel.org/r/20221119005215.3052436-11-shr@devkernel.io Signed-off-by: Stefan Roesch shr@devkernel.io Cc: Chris Mason clm@meta.com Cc: Jens Axboe axboe@kernel.dk Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Yifan Qiao qiaoyifan4@huawei.com --- include/linux/backing-dev.h | 1 + mm/page-writeback.c | 5 +++++ 2 files changed, 6 insertions(+)

diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index 62e15821ff1c..547e35a7715a 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -107,6 +107,7 @@ static inline unsigned long wb_stat_error(void) /* BDI ratio is expressed as part per 1000000 for finer granularity. */ #define BDI_RATIO_SCALE 10000

+u64 bdi_get_min_bytes(struct backing_dev_info *bdi); u64 bdi_get_max_bytes(struct backing_dev_info *bdi); 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); diff --git a/mm/page-writeback.c b/mm/page-writeback.c index b13965fff44c..67ee9b9d6f59 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -773,6 +773,11 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio) } EXPORT_SYMBOL(bdi_set_max_ratio);

+u64 bdi_get_min_bytes(struct backing_dev_info *bdi) +{ + return bdi_get_bytes(bdi->min_ratio); +} + u64 bdi_get_max_bytes(struct backing_dev_info *bdi) { return bdi_get_bytes(bdi->max_ratio);

From: Stefan Roesch shr@devkernel.io

mainline inclusion from mainline-v6.2-rc1 commit 803c98050569850be5fd51a2025c67622de887d9 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAN96I

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

This introduces the bdi_set_min_bytes() function. The min_bytes function does not store the min_bytes value. Instead it converts the min_bytes value into the corresponding ratio value.

Link: https://lkml.kernel.org/r/20221119005215.3052436-13-shr@devkernel.io Signed-off-by: Stefan Roesch shr@devkernel.io Cc: Chris Mason clm@meta.com Cc: Jens Axboe axboe@kernel.dk Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Yifan Qiao qiaoyifan4@huawei.com --- include/linux/backing-dev.h | 1 + mm/page-writeback.c | 14 ++++++++++++++ 2 files changed, 15 insertions(+)

diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index 547e35a7715a..d8da5391f3d5 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -111,6 +111,7 @@ u64 bdi_get_min_bytes(struct backing_dev_info *bdi); u64 bdi_get_max_bytes(struct backing_dev_info *bdi); 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_min_bytes(struct backing_dev_info *bdi, u64 min_bytes); int bdi_set_max_bytes(struct backing_dev_info *bdi, u64 max_bytes); int bdi_set_strict_limit(struct backing_dev_info *bdi, unsigned int strict_limit);

diff --git a/mm/page-writeback.c b/mm/page-writeback.c index a85d3716b652..e1cd2930853b 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -783,6 +783,20 @@ u64 bdi_get_min_bytes(struct backing_dev_info *bdi) return bdi_get_bytes(bdi->min_ratio); }

+int bdi_set_min_bytes(struct backing_dev_info *bdi, u64 min_bytes) +{ + int ret; + unsigned long pages = min_bytes >> PAGE_SHIFT; + unsigned long min_ratio; + + ret = bdi_check_pages_limit(pages); + if (ret) + return ret; + + min_ratio = bdi_ratio_from_pages(pages); + return __bdi_set_min_ratio(bdi, min_ratio); +} + u64 bdi_get_max_bytes(struct backing_dev_info *bdi) { return bdi_get_bytes(bdi->max_ratio);

From: Stefan Roesch shr@devkernel.io

mainline inclusion from mainline-v6.2-rc1 commit 9c832a8d571784c998d0f9f5df480c62f7f3064c category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAN96I

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

This documents the new /sys/class/bdi/<bdi>/min_bytes knob.

[akpm@linux-foundation.org: fix htmldocs warnings] Link: https://lkml.kernel.org/r/20221119005215.3052436-15-shr@devkernel.io Signed-off-by: Stefan Roesch shr@devkernel.io Cc: Chris Mason clm@meta.com Cc: Jens Axboe axboe@kernel.dk Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Yifan Qiao qiaoyifan4@huawei.com --- Documentation/ABI/testing/sysfs-class-bdi | 15 +++++++++++++++ 1 file changed, 15 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-class-bdi b/Documentation/ABI/testing/sysfs-class-bdi index 726c2e2c15cf..5b1341ffbd6d 100644 --- a/Documentation/ABI/testing/sysfs-class-bdi +++ b/Documentation/ABI/testing/sysfs-class-bdi @@ -50,6 +50,21 @@ max_ratio (read-write)

(read-write)

+What: /sys/class/bdi/<bdi>/min_bytes +Date: October 2022 +Contact: Stefan Roesch shr@devkernel.io +Description: + Under normal circumstances each device is given a part of the + total write-back cache that relates to its current average + writeout speed in relation to the other devices. + + The 'min_bytes' parameter allows assigning a minimum + percentage of the write-back cache to a particular device + expressed in bytes. + For example, this is useful for providing a minimum QoS. + + (read-write) + What: /sys/class/bdi/<bdi>/max_bytes Date: October 2022 Contact: Stefan Roesch shr@devkernel.io

From: Stefan Roesch shr@devkernel.io

mainline inclusion from mainline-v6.2-rc1 commit bca52dcbadc583f4db6435599c44a79f97293f06 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAN96I

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

--------------------------------

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

Link: https://lkml.kernel.org/r/20221119005215.3052436-17-shr@devkernel.io Signed-off-by: Stefan Roesch shr@devkernel.io Cc: Chris Mason clm@meta.com Cc: Jens Axboe axboe@kernel.dk Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Yifan Qiao qiaoyifan4@huawei.com --- mm/backing-dev.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+)

diff --git a/mm/backing-dev.c b/mm/backing-dev.c index b3595a3b06b2..984df664b967 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -197,6 +197,25 @@ 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) @@ -295,6 +314,7 @@ 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,

From: Stefan Roesch shr@devkernel.io

mainline inclusion from mainline-v6.2-rc1 commit 2c44af4f2aaa260199f218f11920c406e688693c category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAN96I

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

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This introduces bdi_set_min_ratio_no_scale(). It uses the max granularity for the ratio. This function by the new sysfs knob min_ratio_fine.

Link: https://lkml.kernel.org/r/20221119005215.3052436-19-shr@devkernel.io Signed-off-by: Stefan Roesch shr@devkernel.io Cc: Chris Mason clm@meta.com Cc: Jens Axboe axboe@kernel.dk Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Yifan Qiao qiaoyifan4@huawei.com --- include/linux/backing-dev.h | 1 + mm/page-writeback.c | 7 +++++++ 2 files changed, 8 insertions(+)

diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index e2a09835d736..b10df87d6c34 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -111,6 +111,7 @@ u64 bdi_get_min_bytes(struct backing_dev_info *bdi); u64 bdi_get_max_bytes(struct backing_dev_info *bdi); 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_min_ratio_no_scale(struct backing_dev_info *bdi, unsigned int min_ratio); int bdi_set_max_ratio_no_scale(struct backing_dev_info *bdi, unsigned int max_ratio); int bdi_set_min_bytes(struct backing_dev_info *bdi, u64 min_bytes); int bdi_set_max_bytes(struct backing_dev_info *bdi, u64 max_bytes); diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 42a9b2664c10..6adf00de9eba 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -723,6 +723,8 @@ static int __bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ra unsigned int delta; int ret = 0;

+ if (min_ratio > 100 * BDI_RATIO_SCALE) + return -EINVAL; min_ratio *= BDI_RATIO_SCALE;

spin_lock_bh(&bdi_lock); @@ -767,6 +769,11 @@ static int __bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ra return ret; }

+int bdi_set_min_ratio_no_scale(struct backing_dev_info *bdi, unsigned int min_ratio) +{ + return __bdi_set_min_ratio(bdi, min_ratio); +} + int bdi_set_max_ratio_no_scale(struct backing_dev_info *bdi, unsigned int max_ratio) { return __bdi_set_max_ratio(bdi, max_ratio);

From: Stefan Roesch shr@devkernel.io

mainline inclusion from mainline-v6.2-rc1 commit eba39236f18da7a50b6c51df5d902ee72c43e760 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAN96I

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

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This documents the new /sys/class/bdi/<bdi>/max_ratio_fine knob.

[akpm@linux-foundation.org: fix htmldocs warnings] Link: https://lkml.kernel.org/r/20221119005215.3052436-21-shr@devkernel.io Signed-off-by: Stefan Roesch shr@devkernel.io Cc: Chris Mason clm@meta.com Cc: Jens Axboe axboe@kernel.dk Signed-off-by: Andrew Morton akpm@linux-foundation.org Conflicts: Documentation/ABI/testing/sysfs-class-bdi [Context differences] Signed-off-by: Yifan Qiao qiaoyifan4@huawei.com --- Documentation/ABI/testing/sysfs-class-bdi | 15 +++++++++++++++ 1 file changed, 15 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-class-bdi b/Documentation/ABI/testing/sysfs-class-bdi index 6e23417e0dd9..f1119b36f341 100644 --- a/Documentation/ABI/testing/sysfs-class-bdi +++ b/Documentation/ABI/testing/sysfs-class-bdi @@ -39,6 +39,21 @@ min_ratio (read-write) percentage of the write-back cache to a particular device. For example, this is useful for providing a minimum QoS.

+What: /sys/class/bdi/<bdi>/min_ratio_fine +Date: November 2022 +Contact: Stefan Roesch shr@devkernel.io +Description: + Under normal circumstances each device is given a part of the + total write-back cache that relates to its current average + writeout speed in relation to the other devices. + + The 'min_ratio_fine' parameter allows assigning a minimum reserve + of the write-back cache to a particular device. The value is + expressed as part of 1 million. For example, this is useful for + providing a minimum QoS. + + (read-write) + max_ratio (read-write)

Allows limiting a particular device to use not more than the

From: Jingbo Xu jefflexu@linux.alibaba.com

mainline inclusion from mainline-v6.7 commit e0646b7590084a5bf3b056d3ad871d9379d2c25a category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAN96I

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

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Since now bdi->min_ratio is part per million, fix the wrong arithmetic. Otherwise it will fail with -EINVAL when setting a reasonable min_ratio, as it tries to set min_ratio to (min_ratio * BDI_RATIO_SCALE) in percentage unit, which exceeds 100% anyway.

# cat /sys/class/bdi/253:0/min_ratio 0 # cat /sys/class/bdi/253:0/max_ratio 100 # echo 1 > /sys/class/bdi/253:0/min_ratio -bash: echo: write error: Invalid argument

Link: https://lkml.kernel.org/r/20231219142508.86265-2-jefflexu@linux.alibaba.com Fixes: 8021fb3232f2 ("mm: split off __bdi_set_min_ratio() function") Signed-off-by: Jingbo Xu jefflexu@linux.alibaba.com Reported-by: Joseph Qi joseph.qi@linux.alibaba.com Cc: Matthew Wilcox (Oracle) willy@infradead.org Cc: Stefan Roesch shr@devkernel.io Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Yifan Qiao qiaoyifan4@huawei.com --- mm/page-writeback.c | 1 - 1 file changed, 1 deletion(-)

diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 0e72abc6cb60..0062f1146a30 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -725,7 +725,6 @@ static int __bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ra

if (min_ratio > 100 * BDI_RATIO_SCALE) return -EINVAL; - min_ratio *= BDI_RATIO_SCALE;

spin_lock_bh(&bdi_lock); if (min_ratio > bdi->max_ratio) {