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Message-ID: <0000013ab7e86f8a-4adb8b81-19be-4264-96f1-924aaf3819f2-000000@email.amazonses.com> Date: Wed, 31 Oct 2012 17:39:54 +0000 From: Christoph Lameter <cl@...ux.com> To: Shan Wei <shanwei88@...il.com> cc: jesse@...ira.com, dev@...nvswitch.org, NetDev <netdev@...r.kernel.org>, Kernel-Maillist <linux-kernel@...r.kernel.org>, David Miller <davem@...emloft.net> Subject: Re: [PATCH 4/9] net: openvswitch: use this_cpu_ptr per-cpu helper On Wed, 31 Oct 2012, Shan Wei wrote: > --- a/net/openvswitch/datapath.c > +++ b/net/openvswitch/datapath.c > @@ -208,7 +208,7 @@ void ovs_dp_process_received_packet(struct vport *p, struct sk_buff *skb) > int error; > int key_len; > > - stats = per_cpu_ptr(dp->stats_percpu, smp_processor_id()); > + stats = this_cpu_ptr(dp->stats_percpu); Well this is an improvement and may be ok if the preemption is disabled at this point. There is another possibility here to use this_cpu_read/add/inc instead of determining the pointer to the local cpu first and then performing operations on the fields. The pointer relocation with this_cpu_xxx ops is implicit in the instructions and safe against changing of processors. It would also save us the determination of a pointer to the current cpus stats structure. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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