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Date: Tue, 24 Aug 2021 12:24:28 -0300
From: Marcelo Tosatti <mtosatti@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: Nitesh Lal <nilal@...hat.com>,
Nicolas Saenz Julienne <nsaenzju@...hat.com>,
Frederic Weisbecker <frederic@...nel.org>,
Christoph Lameter <cl@...ux.com>,
Juri Lelli <juri.lelli@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Alex Belits <abelits@...its.com>, Peter Xu <peterx@...hat.com>,
Marcelo Tosatti <mtosatti@...hat.com>
Subject: [patch V3 5/8] task isolation: sync vmstats conditional on changes
Rather than syncing VM-stats on every return to userspace
(or VM-entry), keep track of changes through a per-CPU bool.
This improves performance when enabling task isolated
for vcpu VMs.
Signed-off-by: Marcelo Tosatti <mtosatti@...hat.com>
Index: linux-2.6/include/linux/vmstat.h
===================================================================
--- linux-2.6.orig/include/linux/vmstat.h
+++ linux-2.6/include/linux/vmstat.h
@@ -22,7 +22,16 @@ int sysctl_vm_numa_stat_handler(struct c
#endif
#ifdef CONFIG_SMP
-void sync_vmstat(void);
+extern struct static_key vmstat_sync_enabled;
+
+void __sync_vmstat(void);
+static inline void sync_vmstat(void)
+{
+ if (static_key_false(&vmstat_sync_enabled))
+ __sync_vmstat();
+}
+
+void init_sync_vmstat(void);
#else
static inline void sync_vmstat(void)
{
Index: linux-2.6/kernel/task_isolation.c
===================================================================
--- linux-2.6.orig/kernel/task_isolation.c
+++ linux-2.6/kernel/task_isolation.c
@@ -21,6 +21,17 @@
#include <linux/mm.h>
#include <linux/vmstat.h>
+void __tsk_isol_exit(struct task_struct *tsk)
+{
+ struct isol_info *i;
+
+ i = tsk->isol_info;
+ if (!i)
+ return;
+
+ static_key_slow_dec(&vmstat_sync_enabled);
+}
+
void __tsk_isol_free(struct task_struct *tsk)
{
if (!tsk->isol_info)
@@ -92,6 +103,12 @@ static struct isol_info *tsk_isol_alloc_
if (unlikely(!info))
return ERR_PTR(-ENOMEM);
+ preempt_disable();
+ init_sync_vmstat();
+ preempt_enable();
+
+ static_key_slow_inc(&vmstat_sync_enabled);
+
return info;
}
Index: linux-2.6/mm/vmstat.c
===================================================================
--- linux-2.6.orig/mm/vmstat.c
+++ linux-2.6/mm/vmstat.c
@@ -28,6 +28,7 @@
#include <linux/mm_inline.h>
#include <linux/page_ext.h>
#include <linux/page_owner.h>
+#include <linux/sched/isolation.h>
#include "internal.h"
@@ -306,6 +307,22 @@ void set_pgdat_percpu_threshold(pg_data_
}
}
+struct static_key vmstat_sync_enabled;
+static DEFINE_PER_CPU_ALIGNED(bool, vmstat_dirty);
+
+static inline void mark_vmstat_dirty(void)
+{
+ if (!static_key_false(&vmstat_sync_enabled))
+ return;
+
+ raw_cpu_write(vmstat_dirty, true);
+}
+
+void init_sync_vmstat(void)
+{
+ raw_cpu_write(vmstat_dirty, true);
+}
+
/*
* For use when we know that interrupts are disabled,
* or when we know that preemption is disabled and that
@@ -328,6 +345,7 @@ void __mod_zone_page_state(struct zone *
x = 0;
}
__this_cpu_write(*p, x);
+ mark_vmstat_dirty();
}
EXPORT_SYMBOL(__mod_zone_page_state);
@@ -359,6 +377,7 @@ void __mod_node_page_state(struct pglist
x = 0;
}
__this_cpu_write(*p, x);
+ mark_vmstat_dirty();
}
EXPORT_SYMBOL(__mod_node_page_state);
@@ -399,6 +418,7 @@ void __inc_zone_state(struct zone *zone,
zone_page_state_add(v + overstep, zone, item);
__this_cpu_write(*p, -overstep);
}
+ mark_vmstat_dirty();
}
void __inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
@@ -417,6 +437,7 @@ void __inc_node_state(struct pglist_data
node_page_state_add(v + overstep, pgdat, item);
__this_cpu_write(*p, -overstep);
}
+ mark_vmstat_dirty();
}
void __inc_zone_page_state(struct page *page, enum zone_stat_item item)
@@ -445,6 +466,7 @@ void __dec_zone_state(struct zone *zone,
zone_page_state_add(v - overstep, zone, item);
__this_cpu_write(*p, overstep);
}
+ mark_vmstat_dirty();
}
void __dec_node_state(struct pglist_data *pgdat, enum node_stat_item item)
@@ -463,6 +485,7 @@ void __dec_node_state(struct pglist_data
node_page_state_add(v - overstep, pgdat, item);
__this_cpu_write(*p, overstep);
}
+ mark_vmstat_dirty();
}
void __dec_zone_page_state(struct page *page, enum zone_stat_item item)
@@ -526,6 +549,7 @@ static inline void mod_zone_state(struct
if (z)
zone_page_state_add(z, zone, item);
+ mark_vmstat_dirty();
}
void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
@@ -594,6 +618,7 @@ static inline void mod_node_state(struct
if (z)
node_page_state_add(z, pgdat, item);
+ mark_vmstat_dirty();
}
void mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item,
@@ -1964,13 +1989,18 @@ static void vmstat_shepherd(struct work_
round_jiffies_relative(sysctl_stat_interval));
}
-void sync_vmstat(void)
+void __sync_vmstat(void)
{
int cpu;
cpu = get_cpu();
+ if (per_cpu(vmstat_dirty, cpu) == false) {
+ put_cpu();
+ return;
+ }
refresh_cpu_vm_stats(false);
+ raw_cpu_write(vmstat_dirty, false);
put_cpu();
/*
Index: linux-2.6/include/linux/task_isolation.h
===================================================================
--- linux-2.6.orig/include/linux/task_isolation.h
+++ linux-2.6/include/linux/task_isolation.h
@@ -24,6 +24,13 @@ static inline void tsk_isol_free(struct
__tsk_isol_free(tsk);
}
+void __tsk_isol_exit(struct task_struct *tsk);
+static inline void tsk_isol_exit(struct task_struct *tsk)
+{
+ if (tsk->isol_info)
+ __tsk_isol_exit(tsk);
+}
+
int prctl_task_isolation_int_get(unsigned long cmd, void __user *addr,
unsigned long arg4, unsigned long arg5);
int prctl_task_isolation_int_set(unsigned long cmd, void __user *addr,
@@ -59,6 +66,10 @@ static inline void tsk_isol_free(struct
{
}
+static inline void tsk_isol_exit(struct task_struct *tsk)
+{
+}
+
static inline int prctl_task_isolation_feat(unsigned long arg2,
unsigned long arg3,
unsigned long arg4,
Index: linux-2.6/kernel/exit.c
===================================================================
--- linux-2.6.orig/kernel/exit.c
+++ linux-2.6/kernel/exit.c
@@ -64,6 +64,7 @@
#include <linux/rcuwait.h>
#include <linux/compat.h>
#include <linux/io_uring.h>
+#include <linux/task_isolation.h>
#include <linux/uaccess.h>
#include <asm/unistd.h>
@@ -778,6 +779,7 @@ void __noreturn do_exit(long code)
}
io_uring_files_cancel(tsk->files);
+ tsk_isol_exit(tsk);
exit_signals(tsk); /* sets PF_EXITING */
/* sync mm's RSS info before statistics gathering */
Index: linux-2.6/kernel/fork.c
===================================================================
--- linux-2.6.orig/kernel/fork.c
+++ linux-2.6/kernel/fork.c
@@ -2371,6 +2371,7 @@ bad_fork_free_pid:
if (pid != &init_struct_pid)
free_pid(pid);
bad_fork_cleanup_task_isolation:
+ tsk_isol_exit(p);
tsk_isol_free(p);
bad_fork_cleanup_thread:
exit_thread(p);
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