The patch titled
Subject: mm/vmstat: use xchg in cpu_vm_stats_fold
has been added to the -mm mm-unstable branch. Its filename is
mm-vmstat-use-xchg-in-cpu_vm_stats_fold.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-vmstat-use-xchg-in-cpu_vm_stats_fold.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: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
Subject: mm/vmstat: use xchg in cpu_vm_stats_fold
Date: Mon, 13 Mar 2023 13:25:16 -0300
In preparation to switch vmstat shepherd to flush per-CPU counters
remotely, use xchg instead of a pair of read/write instructions.
Link: https://lkml.kernel.org/r/20230313162634.482796394@xxxxxxxxxx
Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
Cc: Aaron Tomlin <atomlin@xxxxxxxxxxx>
Cc: Christian König <christian.koenig@xxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Frederic Weisbecker <frederic@xxxxxxxxxx>
Cc: Heiko Carstens <hca@xxxxxxxxxxxxx>
Cc: Huacai Chen <chenhuacai@xxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: "Russell King (Oracle)" <linux@xxxxxxxxxxxxxxx>
Cc: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/mm/vmstat.c~mm-vmstat-use-xchg-in-cpu_vm_stats_fold
+++ a/mm/vmstat.c
@@ -924,7 +924,7 @@ static int refresh_cpu_vm_stats(bool do_
}
/*
- * Fold the data for an offline cpu into the global array.
+ * Fold the data for a cpu into the global array.
* There cannot be any access by the offline cpu and therefore
* synchronization is simplified.
*/
@@ -945,8 +945,7 @@ void cpu_vm_stats_fold(int cpu)
if (pzstats->vm_stat_diff[i]) {
int v;
- v = pzstats->vm_stat_diff[i];
- pzstats->vm_stat_diff[i] = 0;
+ v = xchg(&pzstats->vm_stat_diff[i], 0);
atomic_long_add(v, &zone->vm_stat[i]);
global_zone_diff[i] += v;
}
@@ -956,8 +955,7 @@ void cpu_vm_stats_fold(int cpu)
if (pzstats->vm_numa_event[i]) {
unsigned long v;
- v = pzstats->vm_numa_event[i];
- pzstats->vm_numa_event[i] = 0;
+ v = xchg(&pzstats->vm_numa_event[i], 0);
zone_numa_event_add(v, zone, i);
}
}
@@ -973,8 +971,7 @@ void cpu_vm_stats_fold(int cpu)
if (p->vm_node_stat_diff[i]) {
int v;
- v = p->vm_node_stat_diff[i];
- p->vm_node_stat_diff[i] = 0;
+ v = xchg(&p->vm_node_stat_diff[i], 0);
atomic_long_add(v, &pgdat->vm_stat[i]);
global_node_diff[i] += v;
}
_
Patches currently in -mm which might be from mtosatti@xxxxxxxxxx are
this_cpu_cmpxchg-arm64-switch-this_cpu_cmpxchg-to-locked-add-_local-function.patch
this_cpu_cmpxchg-loongarch-switch-this_cpu_cmpxchg-to-locked-add-_local-function.patch
this_cpu_cmpxchg-s390-switch-this_cpu_cmpxchg-to-locked-add-_local-function.patch
this_cpu_cmpxchg-x86-switch-this_cpu_cmpxchg-to-locked-add-_local-function.patch
add-this_cpu_cmpxchg_local-and-asm-generic-definitions.patch
convert-this_cpu_cmpxchg-users-to-this_cpu_cmpxchg_local.patch
mm-vmstat-switch-counter-modification-to-cmpxchg.patch
vmstat-switch-per-cpu-vmstat-counters-to-32-bits.patch
mm-vmstat-use-xchg-in-cpu_vm_stats_fold.patch
mm-vmstat-switch-vmstat-shepherd-to-flush-per-cpu-counters-remotely.patch
mm-vmstat-refresh-stats-remotely-instead-of-via-work-item.patch
vmstat-add-pcp-remote-node-draining-via-cpu_vm_stats_fold.patch
