linux-kernel - Re: [PATCH] riscv: use the generic string routines

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Date:   Wed, 04 Aug 2021 13:40:16 -0700 (PDT)
From:   Palmer Dabbelt <palmer@...belt.com>
To:     mcroce@...ux.microsoft.com, mcroce@...ux.microsoft.com
CC:     linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arch@...r.kernel.org,
        Paul Walmsley <paul.walmsley@...ive.com>,
        aou@...s.berkeley.edu, Atish Patra <Atish.Patra@....com>,
        kernel@...il.dk, akira.tsukamoto@...il.com, drew@...gleboard.org,
        bmeng.cn@...il.com, David.Laight@...lab.com, guoren@...nel.org,
        Christoph Hellwig <hch@...radead.org>
Subject:     Re: [PATCH] riscv: use the generic string routines

On Tue, 03 Aug 2021 09:54:34 PDT (-0700), mcroce@...ux.microsoft.com wrote:
> On Mon, Jul 19, 2021 at 1:44 PM Matteo Croce <mcroce@...ux.microsoft.com> wrote:
>>
>> From: Matteo Croce <mcroce@...rosoft.com>
>>
>> Use the generic routines which handle alignment properly.
>>
>> These are the performances measured on a BeagleV machine for a
>> 32 mbyte buffer:
>>
>> memcpy:
>> original aligned:        75 Mb/s
>> original unaligned:      75 Mb/s
>> new aligned:            114 Mb/s
>> new unaligned:          107 Mb/s
>>
>> memset:
>> original aligned:       140 Mb/s
>> original unaligned:     140 Mb/s
>> new aligned:            241 Mb/s
>> new unaligned:          241 Mb/s
>>
>> TCP throughput with iperf3 gives a similar improvement as well.
>>
>> This is the binary size increase according to bloat-o-meter:
>>
>> add/remove: 0/0 grow/shrink: 4/2 up/down: 432/-36 (396)
>> Function                                     old     new   delta
>> memcpy                                        36     324    +288
>> memset                                        32     148    +116
>> strlcpy                                      116     132     +16
>> strscpy_pad                                   84      96     +12
>> strlcat                                      176     164     -12
>> memmove                                       76      52     -24
>> Total: Before=1225371, After=1225767, chg +0.03%
>>
>> Signed-off-by: Matteo Croce <mcroce@...rosoft.com>
>> Signed-off-by: Emil Renner Berthing <kernel@...il.dk>
>> ---
>
> Hi,
>
> can someone have a look at this change and share opinions?

This LGTM.  How are the generic string routines landing?  I'm happy to 
take this into my for-next, but IIUC we need the optimized generic 
versions first so we don't have a performance regression falling back to 
the trivial ones for a bit.  Is there a shared tag I can pull in?