+ mm-page_alloc-add-trace-event-for-totalreserve_pages-calculation.patch added to mm-unstable branch

+ mm-page_alloc-add-trace-event-for-totalreserve_pages-calculation.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/page_alloc: add trace event for totalreserve_pages calculation
has been added to the -mm mm-unstable branch.  Its filename is
     mm-page_alloc-add-trace-event-for-totalreserve_pages-calculation.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-page_alloc-add-trace-event-for-totalreserve_pages-calculation.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Martin Liu <liumartin@google.com>
Subject: mm/page_alloc: add trace event for totalreserve_pages calculation
Date: Sat, 8 Mar 2025 03:46:02 +0000

This commit introduces a new trace event,
`mm_calculate_totalreserve_pages`, which reports the new reserve value at
the exact time when it takes effect.

The `totalreserve_pages` value represents the total amount of memory
reserved across all zones and nodes in the system.  This reserved memory
is crucial for ensuring that critical kernel operations have access to
sufficient memory, even under memory pressure.

By tracing the `totalreserve_pages` value, developers can gain insights
that how the total reserved memory changes over time.

Link: https://lkml.kernel.org/r/20250308034606.2036033-4-liumartin@google.com
Signed-off-by: Martin Liu <liumartin@google.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/trace/events/kmem.h |   18 ++++++++++++++++++
 mm/page_alloc.c             |    1 +
 2 files changed, 19 insertions(+)

--- a/include/trace/events/kmem.h~mm-page_alloc-add-trace-event-for-totalreserve_pages-calculation
+++ a/include/trace/events/kmem.h
@@ -402,6 +402,24 @@ TRACE_EVENT(mm_setup_per_zone_lowmem_res
 		  __entry->lowmem_reserve)
 );
 
+TRACE_EVENT(mm_calculate_totalreserve_pages,
+
+	TP_PROTO(unsigned long totalreserve_pages),
+
+	TP_ARGS(totalreserve_pages),
+
+	TP_STRUCT__entry(
+		__field(unsigned long, totalreserve_pages)
+	),
+
+	TP_fast_assign(
+		__entry->totalreserve_pages = totalreserve_pages;
+	),
+
+	TP_printk("totalreserve_pages=%lu", __entry->totalreserve_pages)
+);
+
+
 /*
  * Required for uniquely and securely identifying mm in rss_stat tracepoint.
  */
--- a/mm/page_alloc.c~mm-page_alloc-add-trace-event-for-totalreserve_pages-calculation
+++ a/mm/page_alloc.c
@@ -5914,6 +5914,7 @@ static void calculate_totalreserve_pages
 		}
 	}
 	totalreserve_pages = reserve_pages;
+	trace_mm_calculate_totalreserve_pages(totalreserve_pages);
 }
 
 /*
_

Patches currently in -mm which might be from liumartin@google.com are

mm-page_alloc-add-trace-event-for-per-zone-watermark-setup.patch
mm-page_alloc-add-trace-event-for-per-zone-lowmem-reserve-setup.patch
mm-page_alloc-add-trace-event-for-totalreserve_pages-calculation.patch