[PATCH] um: allow using glibc string functions instead of generics

[Richard Weinberger]

----- Ursprüngliche Mail -----
> Von: "anton ivanov" <anton.ivanov at cambridgegreys.com>
> An: "richard" <richard at nod.at>
> CC: "linux-um" <linux-um at lists.infradead.org>
> Gesendet: Dienstag, 10. November 2020 22:33:48
> Betreff: Re: [PATCH] um: allow using glibc string functions instead of generics

> On 10/11/2020 21:29, Richard Weinberger wrote:
>> ----- Ursprüngliche Mail -----
>>> Von: "anton ivanov" <anton.ivanov at cambridgegreys.com>
>>>> On what workload did you see such a huge performance improvement?
>>> File IO ~ 1% or thereabouts, iperf - 2-4%.
>>>
>>>> The in-kernel variants of memcpy and such are already well optimized.
>>> UML has no string.h in asm which means it falls back to
>>> asm-generic/string.h which in turn pulls in the ones from lib/string.c
>>>
>>> These are not optimized.
>> Hmmm, I think it should use the highly optimized variants from arch/x86.
> 
> That is the other option - to bring in string32.h and string64.h from x86.

Yes, I thought we do so already. I fear we list this feature after some code
cleanup a long time ago.

I'm happy with either option.

Thanks,
//richard