From mboxrd@z Thu Jan 1 00:00:00 1970 From: Raghavendra K T Subject: Re: [PATCH RFC 0/2] Optimize the snmp stat aggregation for large cpus Date: Wed, 26 Aug 2015 15:55:05 +0530 Message-ID: <55DD9401.9090809@linux.vnet.ibm.com> References: <1440489266-31127-1-git-send-email-raghavendra.kt@linux.vnet.ibm.com> <20150825.160730.1747721171751442778.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: kuznet@ms2.inr.ac.ru, jmorris@namei.org, yoshfuji@linux-ipv6.org, kaber@trash.net, jiri@resnulli.us, edumazet@google.com, hannes@stressinduktion.org, tom@herbertland.com, azhou@nicira.com, ebiederm@xmission.com, ipm@chirality.org.uk, nicolas.dichtel@6wind.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, anton@au1.ibm.com, nacc@linux.vnet.ibm.com, srikar@linux.vnet.ibm.com To: David Miller Return-path: In-Reply-To: <20150825.160730.1747721171751442778.davem@davemloft.net> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 08/26/2015 04:37 AM, David Miller wrote: > From: Raghavendra K T > Date: Tue, 25 Aug 2015 13:24:24 +0530 > >> Please let me know if you have suggestions/comments. > > Like Eric Dumazet said the idea is good but needs some adjustments. > > You might want to see whether a per-cpu work buffer works for this. sure, Let me know if I understood correctly, we allocate the temp buffer, we will have a "add_this_cpu_data" function and do for_each_online_cpu(cpu) smp_call_function_single(cpu, add_this_cpu_data, buffer, 1) if not could you please point to an example you had in mind. > > It's extremely unfortunately that we can't depend upon the destination > buffer being properly aligned, because we wouldn't need a temporary > scratch area if it were aligned properly. True, But I think for 64 bit cpus when (pad == 0) we can go ahead and use stats array directly and get rid of put_unaligned(). is it correct? (my internal initial patch had this version but thought it is ugly to have ifdef BITS_PER_LONG==64)