linux-kernel - Re: [PATCH RFC V2 2/2] net: Optimize snmp stat aggregation by walking all the percpu data at once

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Message-Id: <20150827.113823.214019265460582055.davem@davemloft.net>
Date:	Thu, 27 Aug 2015 11:38:23 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	raghavendra.kt@...ux.vnet.ibm.com
Cc:	kuznet@....inr.ac.ru, jmorris@...ei.org, yoshfuji@...ux-ipv6.org,
	kaber@...sh.net, jiri@...nulli.us, edumazet@...gle.com,
	hannes@...essinduktion.org, tom@...bertland.com, azhou@...ira.com,
	ebiederm@...ssion.com, ipm@...rality.org.uk,
	nicolas.dichtel@...nd.com, serge.hallyn@...onical.com,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	anton@....ibm.com, nacc@...ux.vnet.ibm.com,
	srikar@...ux.vnet.ibm.com
Subject: Re: [PATCH RFC V2 2/2] net: Optimize snmp stat aggregation by
 walking all the percpu data at once

From: Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>
Date: Wed, 26 Aug 2015 23:07:33 +0530

> @@ -4641,10 +4647,12 @@ static inline void __snmp6_fill_stats64(u64 *stats, void __percpu *mib,
>  static void snmp6_fill_stats(u64 *stats, struct inet6_dev *idev, int attrtype,
>  			     int bytes)
>  {
> +	u64 buff[IPSTATS_MIB_MAX] = {0,};
> +
>  	switch (attrtype) {
>  	case IFLA_INET6_STATS:
> -		__snmp6_fill_stats64(stats, idev->stats.ipv6,

I would suggest using an explicit memset() here, it makes the overhead incurred
by this scheme clearer.

Thanks.
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