linux 6.1.y: base: Remove our watermark_scale_factor patch, which doesn't feel needed anymore, and add a selection of patches from Zen: Input: evdev - use call_rcu when detaching client, mm: Lower the non-hugetlbpage pageblock size to reduce scheduling delays and mm: Don't hog the CPU and zone lock in rmqueue_bulk().
379cbab18b2aafb56f20f22bc56be8
This commit is contained in:
Tk-Glitch
@@ -403,34 +403,6 @@ index 84badf00647e..6a922bca9f39 100644
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2.28.0
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From 816ee502759e954304693813bd03d94986b28dba Mon Sep 17 00:00:00 2001
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From: Tk-Glitch <ti3nou@gmail.com>
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Date: Mon, 18 Feb 2019 17:40:57 +0100
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Subject: [PATCH 11/17] mm: Set watermark_scale_factor to 200 (from 10)
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Multiple users have reported it's helping reducing/eliminating stuttering
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with DXVK.
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---
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mm/page_alloc.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/mm/page_alloc.c b/mm/page_alloc.c
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index 898ff44f2c7b..e72074034793 100644
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--- a/mm/page_alloc.c
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+++ b/mm/page_alloc.c
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@@ -330,7 +330,7 @@ int watermark_boost_factor __read_mostly;
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int min_free_kbytes = 1024;
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int user_min_free_kbytes = -1;
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int watermark_boost_factor __read_mostly = 15000;
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-int watermark_scale_factor = 10;
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+int watermark_scale_factor = 200;
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static unsigned long nr_kernel_pages __initdata;
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static unsigned long nr_all_pages __initdata;
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--
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2.28.0
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From 90240bcd90a568878738e66c0d45bed3e38e347b Mon Sep 17 00:00:00 2001
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From: Tk-Glitch <ti3nou@gmail.com>
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Date: Fri, 19 Apr 2019 12:33:38 +0200
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@@ -490,7 +462,6 @@ index b0cefe94920d..890165099b07 100644
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--
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2.28.0
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From 977812938da7c7226415778c340832141d9278b7 Mon Sep 17 00:00:00 2001
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From: Alexandre Frade <admfrade@gmail.com>
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Date: Mon, 25 Nov 2019 15:13:06 -0300
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@@ -619,3 +590,232 @@ index 36a469150ff9..aee891c9b78a 100644
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--
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2.28.0
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From 379cbab18b5c75c622b93e2c5abdfac141fe9654 Mon Sep 17 00:00:00 2001
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From: Kenny Levinsen <kl@kl.wtf>
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Date: Sun, 27 Dec 2020 14:43:13 +0000
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Subject: [PATCH] ZEN: Input: evdev - use call_rcu when detaching client
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Significant time was spent on synchronize_rcu in evdev_detach_client
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when applications closed evdev devices. Switching VT away from a
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graphical environment commonly leads to mass input device closures,
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which could lead to noticable delays on systems with many input devices.
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Replace synchronize_rcu with call_rcu, deferring reclaim of the evdev
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client struct till after the RCU grace period instead of blocking the
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calling application.
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While this does not solve all slow evdev fd closures, it takes care of a
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good portion of them, including this simple test:
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#include <fcntl.h>
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#include <unistd.h>
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int main(int argc, char *argv[])
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{
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int idx, fd;
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const char *path = "/dev/input/event0";
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for (idx = 0; idx < 1000; idx++) {
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if ((fd = open(path, O_RDWR)) == -1) {
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return -1;
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}
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close(fd);
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}
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return 0;
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}
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Time to completion of above test when run locally:
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Before: 0m27.111s
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After: 0m0.018s
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Signed-off-by: Kenny Levinsen <kl@kl.wtf>
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---
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drivers/input/evdev.c | 19 +++++++++++--------
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1 file changed, 11 insertions(+), 8 deletions(-)
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diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
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index 95f90699d2b17b..2b10fe29d2c8d9 100644
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--- a/drivers/input/evdev.c
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+++ b/drivers/input/evdev.c
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@@ -46,6 +46,7 @@ struct evdev_client {
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struct fasync_struct *fasync;
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struct evdev *evdev;
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struct list_head node;
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+ struct rcu_head rcu;
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enum input_clock_type clk_type;
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bool revoked;
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unsigned long *evmasks[EV_CNT];
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@@ -377,13 +378,22 @@ static void evdev_attach_client(struct evdev *evdev,
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spin_unlock(&evdev->client_lock);
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}
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+static void evdev_reclaim_client(struct rcu_head *rp)
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+{
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+ struct evdev_client *client = container_of(rp, struct evdev_client, rcu);
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+ unsigned int i;
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+ for (i = 0; i < EV_CNT; ++i)
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+ bitmap_free(client->evmasks[i]);
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+ kvfree(client);
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+}
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+
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static void evdev_detach_client(struct evdev *evdev,
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struct evdev_client *client)
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{
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spin_lock(&evdev->client_lock);
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list_del_rcu(&client->node);
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spin_unlock(&evdev->client_lock);
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- synchronize_rcu();
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+ call_rcu(&client->rcu, evdev_reclaim_client);
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}
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static int evdev_open_device(struct evdev *evdev)
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@@ -436,7 +446,6 @@ static int evdev_release(struct inode *inode, struct file *file)
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{
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struct evdev_client *client = file->private_data;
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struct evdev *evdev = client->evdev;
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- unsigned int i;
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mutex_lock(&evdev->mutex);
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@@ -448,11 +457,6 @@ static int evdev_release(struct inode *inode, struct file *file)
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evdev_detach_client(evdev, client);
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- for (i = 0; i < EV_CNT; ++i)
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- bitmap_free(client->evmasks[i]);
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-
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- kvfree(client);
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-
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evdev_close_device(evdev);
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return 0;
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@@ -495,7 +499,6 @@ static int evdev_open(struct inode *inode, struct file *file)
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err_free_client:
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evdev_detach_client(evdev, client);
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- kvfree(client);
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return error;
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}
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From 2aafb56f20e4b63d8c4af172fe9d017c64bc4129 Mon Sep 17 00:00:00 2001
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From: Sultan Alsawaf <sultan@kerneltoast.com>
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Date: Wed, 20 Oct 2021 20:50:11 -0700
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Subject: [PATCH] ZEN: mm: Lower the non-hugetlbpage pageblock size to reduce
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scheduling delays
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The page allocator processes free pages in groups of pageblocks, where
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the size of a pageblock is typically quite large (1024 pages without
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hugetlbpage support). Pageblocks are processed atomically with the zone
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lock held, which can cause severe scheduling delays on both the CPU
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going through the pageblock and any other CPUs waiting to acquire the
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zone lock. A frequent offender is move_freepages_block(), which is used
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by rmqueue() for page allocation.
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As it turns out, there's no requirement for pageblocks to be so large,
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so the pageblock order can simply be reduced to ease the scheduling
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delays and zone lock contention. PAGE_ALLOC_COSTLY_ORDER is used as a
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reasonable setting to ensure non-costly page allocation requests can
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still be serviced without always needing to free up more than one
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pageblock's worth of pages at a time.
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This has a noticeable effect on overall system latency when memory
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pressure is elevated. The various mm functions which operate on
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pageblocks no longer appear in the preemptoff tracer, where previously
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they would spend up to 100 ms on a mobile arm64 CPU processing a
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pageblock with preemption disabled and the zone lock held.
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Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>
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---
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include/linux/pageblock-flags.h | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h
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index 5f1ae07d724b88..97cda629c9e909 100644
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--- a/include/linux/pageblock-flags.h
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+++ b/include/linux/pageblock-flags.h
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@@ -48,7 +48,7 @@ extern unsigned int pageblock_order;
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#else /* CONFIG_HUGETLB_PAGE */
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/* If huge pages are not used, group by MAX_ORDER_NR_PAGES */
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-#define pageblock_order (MAX_ORDER-1)
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+#define pageblock_order PAGE_ALLOC_COSTLY_ORDER
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#endif /* CONFIG_HUGETLB_PAGE */
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From f22bc56be85e69c71c8e36041193856bb8b01525 Mon Sep 17 00:00:00 2001
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From: Sultan Alsawaf <sultan@kerneltoast.com>
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Date: Wed, 20 Oct 2021 20:50:32 -0700
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Subject: [PATCH] ZEN: mm: Don't hog the CPU and zone lock in rmqueue_bulk()
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There is noticeable scheduling latency and heavy zone lock contention
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stemming from rmqueue_bulk's single hold of the zone lock while doing
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its work, as seen with the preemptoff tracer. There's no actual need for
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rmqueue_bulk() to hold the zone lock the entire time; it only does so
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for supposed efficiency. As such, we can relax the zone lock and even
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reschedule when IRQs are enabled in order to keep the scheduling delays
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and zone lock contention at bay. Forward progress is still guaranteed,
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as the zone lock can only be relaxed after page removal.
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With this change, rmqueue_bulk() no longer appears as a serious offender
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in the preemptoff tracer, and system latency is noticeably improved.
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Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>
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---
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mm/page_alloc.c | 23 ++++++++++++++++++-----
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1 file changed, 18 insertions(+), 5 deletions(-)
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diff --git a/mm/page_alloc.c b/mm/page_alloc.c
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index a0b0397e29ee4c..87a983a356530c 100644
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--- a/mm/page_alloc.c
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+++ b/mm/page_alloc.c
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@@ -3119,15 +3119,16 @@ __rmqueue(struct zone *zone, unsigned int order, int migratetype,
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}
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/*
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- * Obtain a specified number of elements from the buddy allocator, all under
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- * a single hold of the lock, for efficiency. Add them to the supplied list.
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- * Returns the number of new pages which were placed at *list.
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+ * Obtain a specified number of elements from the buddy allocator, and relax the
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+ * zone lock when needed. Add them to the supplied list. Returns the number of
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+ * new pages which were placed at *list.
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*/
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static int rmqueue_bulk(struct zone *zone, unsigned int order,
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unsigned long count, struct list_head *list,
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int migratetype, unsigned int alloc_flags)
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{
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- int i, allocated = 0;
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+ const bool can_resched = !preempt_count() && !irqs_disabled();
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+ int i, allocated = 0, last_mod = 0;
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/* Caller must hold IRQ-safe pcp->lock so IRQs are disabled. */
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spin_lock(&zone->lock);
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@@ -3137,6 +3138,18 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order,
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if (unlikely(page == NULL))
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break;
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+ /* Reschedule and ease the contention on the lock if needed */
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+ if (i + 1 < count && ((can_resched && need_resched()) ||
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+ spin_needbreak(&zone->lock))) {
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+ __mod_zone_page_state(zone, NR_FREE_PAGES,
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+ -((i + 1 - last_mod) << order));
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+ last_mod = i + 1;
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+ spin_unlock(&zone->lock);
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+ if (can_resched)
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+ cond_resched();
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+ spin_lock(&zone->lock);
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+ }
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+
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if (unlikely(check_pcp_refill(page, order)))
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continue;
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@@ -3163,7 +3176,7 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order,
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* on i. Do not confuse with 'allocated' which is the number of
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* pages added to the pcp list.
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*/
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- __mod_zone_page_state(zone, NR_FREE_PAGES, -(i << order));
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+ __mod_zone_page_state(zone, NR_FREE_PAGES, -((i - last_mod) << order));
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spin_unlock(&zone->lock);
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return allocated;
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}
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