mirrors/linux
2
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2026-08-31 10:31:33 -04:00
Code Issues Packages Projects Releases Wiki Activity

mm/page_reporting: add page_reporting_delay_ms module parameter

Browse Source 
Free page reporting currently hardcodes a 2-second interval between
reports.  This rigid delay cannot accommodate diverse guest workloads.

This patch introduces a module parameter, page_reporting_delay_ms
(default: 2000), allowing users to tune the reporting rate:
 - Lower values enable aggressive memory reclamation by returning unused
   pages to the host immediately.
 - Higher values help batch pages during spiky allocation/free churn,
   reducing hypercalls and nested page fault overheads.

Setting the delay to 0 is safe and execution is strictly gated by:
 - reporting is only triggered by high-order page frees.
 - expensive hypercalls are bounded by a slot capacity watermark check
   before proceeding.

Link: https://lore.kernel.org/20260731193705.2902728-1-pratmal@google.com
Signed-off-by: Pratyush Mallick <pratmal@google.com>
Reviewed-by: SJ Park <sj@kernel.org>
Acked-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: SeongJae Park <sj@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Pratyush Mallick
2026-07-31 19:37:05 +00:00
committed by Andrew Morton
parent 5120b1e048
commit 7a39f03bc9
2 changed files with 24 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
Documentation/admin-guide/kernel-parameters.txt
View File

@@ -4810,6 +4810,12 @@ Kernel parameters
Adjust the minimal page reporting order. The page
reporting is disabled when it exceeds MAX_PAGE_ORDER.
page_reporting.page_reporting_delay_ms=
[KNL] Free page reporting delay in milliseconds
Format: <unsigned integer>
Adjust the delay in milliseconds between free page
reporting intervals. Default is 2000 (2 seconds).
panic= [KNL] Kernel behaviour on panic: delay <timeout>
timeout > 0: seconds before rebooting
timeout = 0: wait forever

28
mm/page_reporting.c
View File

@@ -48,7 +48,11 @@ MODULE_PARM_DESC(page_reporting_order, "Set page reporting order");
*/
EXPORT_SYMBOL_GPL(page_reporting_order);
#define PAGE_REPORTING_DELAY (2 * HZ)
static unsigned int page_reporting_delay_ms = 2 * MSEC_PER_SEC;
module_param(page_reporting_delay_ms, uint, 0644);
MODULE_PARM_DESC(page_reporting_delay_ms,
"Set page reporting delay in milliseconds");
static struct page_reporting_dev_info __rcu *pr_dev_info __read_mostly;
enum {
@@ -57,6 +61,13 @@ enum {
PAGE_REPORTING_ACTIVE
};
/* schedule work for page reporting */
static void page_reporting_schedule_work(struct page_reporting_dev_info *prdev)
{
queue_delayed_work(system_freezable_wq, &prdev->work,
msecs_to_jiffies(page_reporting_delay_ms));
}
/* request page reporting */
static void
__page_reporting_request(struct page_reporting_dev_info *prdev)
@@ -77,12 +88,10 @@ __page_reporting_request(struct page_reporting_dev_info *prdev)
return;
/*
* Delay the start of work to allow a sizable queue to build. For
* now we are limiting this to running no more than once every
* couple of seconds.
* Delay the start of work to allow a sizable queue to build.
* We limit this based on page_reporting_delay_ms.
*/
queue_delayed_work(system_freezable_wq, &prdev->work,
PAGE_REPORTING_DELAY);
page_reporting_schedule_work(prdev);
}
/* notify prdev of free page reporting request */
@@ -337,13 +346,12 @@ static void page_reporting_process(struct work_struct *work)
err_out:
/*
* If the state has reverted back to requested then there may be
* additional pages to be processed. We will defer for 2s to allow
* more pages to accumulate.
* additional pages to be processed. We will defer by
* page_reporting_delay_ms to allow more pages to accumulate.
*/
state = atomic_cmpxchg(&prdev->state, state, PAGE_REPORTING_IDLE);
if (state == PAGE_REPORTING_REQUESTED)
queue_delayed_work(system_freezable_wq, &prdev->work,
PAGE_REPORTING_DELAY);
page_reporting_schedule_work(prdev);
}
static DEFINE_MUTEX(page_reporting_mutex);