netdev - RE: [PATCH 3/3] powerpc: bpf: implement in-register swap for 64-bit endian operations

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Message-ID: <063D6719AE5E284EB5DD2968C1650D6DB02635FB@AcuExch.aculab.com>
Date:   Fri, 13 Jan 2017 17:17:26 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     "'Naveen N. Rao'" <naveen.n.rao@...ux.vnet.ibm.com>,
        "mpe@...erman.id.au" <mpe@...erman.id.au>
CC:     "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "ast@...com" <ast@...com>,
        "daniel@...earbox.net" <daniel@...earbox.net>,
        "davem@...emloft.net" <davem@...emloft.net>
Subject: RE: [PATCH 3/3] powerpc: bpf: implement in-register swap for 64-bit
 endian operations

From: Naveen N. Rao
> Sent: 13 January 2017 17:10
> Generate instructions to perform the endian conversion using registers,
> rather than generating two memory accesses.
> 
> The "way easier and faster" comment was obviously for the author, not
> the processor.

That rather depends on whether the processor has a store to load forwarder
that will satisfy the read from the store buffer.
I don't know about ppc, but at least some x86 will do that.

	David