Re: [PATCH v3] mm, sysctl: make NUMA stats configurable

[kemi]

On 2017å09æ29æ 05:29, Andrew Morton wrote:
> On Thu, 28 Sep 2017 14:11:41 +0800 Kemi Wang <kemi.wang@xxxxxxxxx> wrote:
> 
>> This is the second step which introduces a tunable interface that allow
>> numa stats configurable for optimizing zone_statistics(), as suggested by
>> Dave Hansen and Ying Huang.
> 
> Looks OK I guess.
> 
> I fiddled with it a lot.  Please consider:
> 

Thanks for your help to make it more graceful! I will be more careful next time.
There may be a typo error in Documentation/sysctl/vm.txt, see comment below.

> From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Subject: mm-sysctl-make-numa-stats-configurable-fix
> 
> - tweak documentation
> 
> - move advisory message from start_kernel() into mm_init() (I'm not sure
>   we really need this message)
> 
> - use strcasecmp() in __parse_vm_numa_stats_mode()
> 
> - clean up coding style amd nessages in sysctl_vm_numa_stats_mode_handler()
> 
> Cc: Aaron Lu <aaron.lu@xxxxxxxxx>
> Cc: Andi Kleen <andi.kleen@xxxxxxxxx>
> Cc: Christopher Lameter <cl@xxxxxxxxx>
> Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
> Cc: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
> Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
> Cc: Jonathan Corbet <corbet@xxxxxxx>
> Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> Cc: Kemi Wang <kemi.wang@xxxxxxxxx>
> Cc: "Luis R . Rodriguez" <mcgrof@xxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> Cc: Tim Chen <tim.c.chen@xxxxxxxxx>
> Cc: Vlastimil Babka <vbabka@xxxxxxx>
> Cc: Ying Huang <ying.huang@xxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> ---
> 
>  Documentation/sysctl/vm.txt |   15 ++++++-------
>  init/main.c                 |    6 ++---
>  mm/vmstat.c                 |   39 +++++++++++++++-------------------
>  3 files changed, 29 insertions(+), 31 deletions(-)
> 
> diff -puN Documentation/sysctl/vm.txt~mm-sysctl-make-numa-stats-configurable-fix Documentation/sysctl/vm.txt
> --- a/Documentation/sysctl/vm.txt~mm-sysctl-make-numa-stats-configurable-fix
> +++ a/Documentation/sysctl/vm.txt
> @@ -853,7 +853,7 @@ ten times more freeable objects than the
>  
>  numa_stats_mode
>  
> -This interface allows numa statistics configurable.
> +This interface allows runtime configuration *or* numa statistics.
>  

typo? or->of/for?

>  When page allocation performance becomes a bottleneck and you can tolerate
>  some possible tool breakage and decreased numa counter precision, you can
> @@ -864,13 +864,14 @@ When page allocation performance is not
>  tooling to work, you can do:
>  	echo [S|s]trict > /proc/sys/vm/numa_stat_mode
>  
> -We recommend automatic detection of numa statistics by system, because numa
> -statistics does not affect system's decision and it is very rarely
> -consumed. you can do:
> +We recommend automatic detection of numa statistics by system, because
> +numa statistics do not affect system decisions and it is very rarely
> +consumed.  In this case you can do:
>  	echo [A|a]uto > /proc/sys/vm/numa_stats_mode
> -This is also system default configuration, with this default setting, numa
> -counters update is skipped unless the counter is *read* by users at least
> -once.
> +
> +This is the system default configuration.  With this default setting, numa
> +counter updates are skipped until the counter is *read* by userspace at
> +least once.
>  
>  ==============================================================
>  
> diff -puN drivers/base/node.c~mm-sysctl-make-numa-stats-configurable-fix drivers/base/node.c
> diff -puN include/linux/vmstat.h~mm-sysctl-make-numa-stats-configurable-fix include/linux/vmstat.h
> diff -puN init/main.c~mm-sysctl-make-numa-stats-configurable-fix init/main.c
> --- a/init/main.c~mm-sysctl-make-numa-stats-configurable-fix
> +++ a/init/main.c
> @@ -504,6 +504,9 @@ static void __init mm_init(void)
>  	pgtable_init();
>  	vmalloc_init();
>  	ioremap_huge_init();
> +#ifdef CONFIG_NUMA
> +	pr_info("vmstat: NUMA stat updates are skipped unless they have been used\n");
> +#endif
>  }
>  
>  asmlinkage __visible void __init start_kernel(void)
> @@ -567,9 +570,6 @@ asmlinkage __visible void __init start_k
>  	sort_main_extable();
>  	trap_init();
>  	mm_init();
> -#ifdef CONFIG_NUMA
> -	pr_info("vmstat: NUMA stats is skipped unless it has been consumed\n");
> -#endif
>  
>  	ftrace_init();
>  
> diff -puN kernel/sysctl.c~mm-sysctl-make-numa-stats-configurable-fix kernel/sysctl.c
> diff -puN mm/page_alloc.c~mm-sysctl-make-numa-stats-configurable-fix mm/page_alloc.c
> diff -puN mm/vmstat.c~mm-sysctl-make-numa-stats-configurable-fix mm/vmstat.c
> --- a/mm/vmstat.c~mm-sysctl-make-numa-stats-configurable-fix
> +++ a/mm/vmstat.c
> @@ -40,13 +40,11 @@ static DEFINE_MUTEX(vm_numa_stats_mode_l
>  
>  static int __parse_vm_numa_stats_mode(char *s)
>  {
> -	const char *str = s;
> -
> -	if (strcmp(str, "auto") == 0 || strcmp(str, "Auto") == 0)
> +	if (strcasecmp(s, "auto"))
>  		vm_numa_stats_mode = VM_NUMA_STAT_AUTO_MODE;
> -	else if (strcmp(str, "strict") == 0 || strcmp(str, "Strict") == 0)
> +	else if (strcasecmp(s, "strict") == 0)
>  		vm_numa_stats_mode = VM_NUMA_STAT_STRICT_MODE;
> -	else if (strcmp(str, "coarse") == 0 || strcmp(str, "Coarse") == 0)
> +	else if (strcasecmp(s, "coarse"))
>  		vm_numa_stats_mode = VM_NUMA_STAT_COARSE_MODE;
>  	else {
>  		pr_warn("Ignoring invalid vm_numa_stats_mode value: %s\n", s);
> @@ -86,30 +84,29 @@ int sysctl_vm_numa_stats_mode_handler(st
>  			/* no change */
>  			mutex_unlock(&vm_numa_stats_mode_lock);
>  			return 0;
> -		} else if (vm_numa_stats_mode == VM_NUMA_STAT_AUTO_MODE)
> +		} else if (vm_numa_stats_mode == VM_NUMA_STAT_AUTO_MODE) {
>  			/*
> -			 * Keep the branch selection in last time when numa stats
> -			 * is changed to auto mode.
> +			 * Keep the branch selection in last time when numa
> +			 * stats is changed to auto mode.
>  			 */
> -			pr_info("numa stats changes from %s mode to auto mode\n",
> -					vm_numa_stats_mode_name[oldval]);
> -		else if (vm_numa_stats_mode == VM_NUMA_STAT_STRICT_MODE) {
> +			pr_info("numa stats changed from %s to auto mode\n",
> +				 vm_numa_stats_mode_name[oldval]);
> +		} else if (vm_numa_stats_mode == VM_NUMA_STAT_STRICT_MODE) {
>  			static_branch_enable(&vm_numa_stats_mode_key);
> -			pr_info("numa stats changes from %s mode to strict mode\n",
> -					vm_numa_stats_mode_name[oldval]);
> +			pr_info("numa stats changes from %s to strict mode\n",
> +				 vm_numa_stats_mode_name[oldval]);
>  		} else if (vm_numa_stats_mode == VM_NUMA_STAT_COARSE_MODE) {
>  			static_branch_disable(&vm_numa_stats_mode_key);
>  			/*
> -			 * Invalidate numa counters when vmstat mode is set to coarse
> -			 * mode, because users can't tell the difference between the
> -			 * dead state and when allocator activity is quiet once
> -			 * zone_statistics() is turned off.
> +			 * Invalidate numa counters when vmstat mode is set to
> +			 * coarse mode, because users can't tell the difference
> +			 * between the dead state and when allocator activity is
> +			 * quiet once zone_statistics() is turned off.
>  			 */
>  			invalid_numa_statistics();
> -			pr_info("numa stats changes from %s mode to coarse mode\n",
> -					vm_numa_stats_mode_name[oldval]);
> -		} else
> -			pr_warn("invalid vm_numa_stats_mode:%d\n", vm_numa_stats_mode);
> +			pr_info("numa stats changes from %s to coarse mode\n",
> +				 vm_numa_stats_mode_name[oldval]);
> +		}
>  	}
>  
>  	mutex_unlock(&vm_numa_stats_mode_lock);
> _
>