Messages in this thread | | | Date | Tue, 13 Nov 2012 17:33:19 +0800 | From | Shan Wei <> | Subject | Re: [PATCH v4 3/9] net: xfrm: use __this_cpu_read per-cpu helper |
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Steffen Klassert said, at 2012/11/13 15:21: > > This should just fetch the tfm pointer, so why exactly __this_cpu_read > is better than __this_cpu_ptr? Please keep in mind that performance is > not the most important thing here. It's much more important that it > works in any case.
[0/9] describes why we should submit this series patches. you are not included in original mail.
this_cpu_ptr relocates and address. this_cpu_read() relocates the address and performs the fetch. If you want to operate on rda(defined as per_cpu) then you can only use this_cpu_ptr. this_cpu_read() saves you more instructions since it can do the relocation and the fetch in one instruction.
More info, please refer to http://www.spinics.net/lists/kernel/msg1435153.html
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