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Re: [lwip-users] Externally allocated memory pool for pbufs


From: Olivier Desenfans
Subject: Re: [lwip-users] Externally allocated memory pool for pbufs
Date: Wed, 8 Nov 2017 10:33:55 +0100

Thanks for the answer, that really clears it up for me. Could you link
the previous question you mention for my own information?

So if I really wanted to use a fixed address for TX buffers, I'd
basically have to reimplement an allocator that makes use of the
uncached zone. Sure sounds inconvenient. Regarding performance, it
probably is slower but it also means more predictability at run-time
as 1) you don't need to perform additional cache operations from
user-space at run-time 2) you avoid additional system calls at
run-time. That sounded more elegant for a real-time system. Anyway,
we'll use run-time cache primitives then.

Thanks a lot for the help,

Olivier

2017-11-07 21:17 GMT+01:00 address@hidden <address@hidden>:
> Olivier Desenfans wrote:
>>
>> Regarding the TX side of things,
>
>
> Keep in mind that most TX functions allocate PBUF_RAM pbufs, which are
> allocated via mem_malloc(). To move this into pools, you'll need some extra
> work.
>
> Also, are you *sure* constructing packets in uncached memory is faster than
> flushing the cache before transmission?
> (Wait a minute, I feel like I have asked this question before here? *g*)
>
> Cheers,
> Simon
>
>
>
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