linux-kernel - Re: [RFC 1/2] workqueue: use the nearest NUMA node, not the local one

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <53C8D6A8.3040400@cn.fujitsu.com>
Date:	Fri, 18 Jul 2014 16:11:20 +0800
From:	Lai Jiangshan <laijs@...fujitsu.com>
To:	Nishanth Aravamudan <nacc@...ux.vnet.ibm.com>
CC:	<benh@...nel.crashing.org>, Joonsoo Kim <iamjoonsoo.kim@....com>,
	David Rientjes <rientjes@...gle.com>,
	Wanpeng Li <liwanp@...ux.vnet.ibm.com>,
	Jiang Liu <jiang.liu@...ux.intel.com>,
	Tony Luck <tony.luck@...el.com>,
	Fenghua Yu <fenghua.yu@...el.com>,
	<linux-ia64@...r.kernel.org>, <linux-mm@...ck.org>,
	<linuxppc-dev@...ts.ozlabs.org>, <linux-kernel@...r.kernel.org>,
	Tejun Heo <tj@...nel.org>
Subject: Re: [RFC 1/2] workqueue: use the nearest NUMA node, not the local
 one

Hi,

I'm curious about what will it happen when alloc_pages_node(memoryless_node).

If the memory is allocated from the most preferable node for the @memoryless_node,
why we need to bother and use cpu_to_mem() in the caller site?

If not, why the memory allocation subsystem refuses to find a preferable node
for @memoryless_node in this case? Does it intend on some purpose or
it can't find in some cases?

Thanks,
Lai

Added CC to Tejun (workqueue maintainer).

On 07/18/2014 07:09 AM, Nishanth Aravamudan wrote:
> In the presence of memoryless nodes, the workqueue code incorrectly uses
> cpu_to_node() to determine what node to prefer memory allocations come
> from. cpu_to_mem() should be used instead, which will use the nearest
> NUMA node with memory.
> 
> Signed-off-by: Nishanth Aravamudan <nacc@...ux.vnet.ibm.com>
> 
> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
> index 35974ac..0bba022 100644
> --- a/kernel/workqueue.c
> +++ b/kernel/workqueue.c
> @@ -3547,7 +3547,12 @@ static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs)
>  		for_each_node(node) {
>  			if (cpumask_subset(pool->attrs->cpumask,
>  					   wq_numa_possible_cpumask[node])) {
> -				pool->node = node;
> +				/*
> +				 * We could use local_memory_node(node) here,
> +				 * but it is expensive and the following caches
> +				 * the same value.
> +				 */
> +				pool->node = cpu_to_mem(cpumask_first(pool->attrs->cpumask));
>  				break;
>  			}
>  		}
> @@ -4921,7 +4926,7 @@ static int __init init_workqueues(void)
>  			pool->cpu = cpu;
>  			cpumask_copy(pool->attrs->cpumask, cpumask_of(cpu));
>  			pool->attrs->nice = std_nice[i++];
> -			pool->node = cpu_to_node(cpu);
> +			pool->node = cpu_to_mem(cpu);
>  
>  			/* alloc pool ID */
>  			mutex_lock(&wq_pool_mutex);
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@...r.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
> 

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/