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RE: RE: [lwip-users] Sizes
From: |
John Kennedy |
Subject: |
RE: RE: [lwip-users] Sizes |
Date: |
Thu, 28 May 2009 07:17:06 -0600 |
Well, just for fun I switched to algorithm 3 and got a 100Kbits/s improvement.
John
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John Kennedy
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-----Original Message-----
From: Simon Goldschmidt [mailto:address@hidden
Sent: Thursday, May 28, 2009 1:16 AM
To: Mailing list for lwIP users
Subject: Re: RE: [lwip-users] Sizes
> BTW which checksum algorithm did base your
> assembly code on? Does anyone know which of the checksum algorithms is the
> fastest?
Unfortunately, that depends largely on your platform. The best thing to do is
to try all of them: call them in a loop on a data buffer that is bigger than
your caches and see which one finishes first.
> I'm a little surprised that other than the call overhead that an
> assembly version of memcpy is much faster than what the complier produces
> from the library?
The difference here is not C or assembly but 'standard' library (written in C,
used on many platforms) or hand-written code that performs well on your
specific platform. And let me tell you there *is* room for improvement here.
For example, some C libraries use byte-by-byte copy if compiled with the
'wrong' options... Nevertheless, the standard library often is not too bad when
copying a well-aligned source to a well-aligned destination.
Simon
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- [lwip-users] Sizes, John Kennedy, 2009/05/27
- Re: [lwip-users] Sizes, Jeff Barber, 2009/05/27
- RE: [lwip-users] Sizes, John Kennedy, 2009/05/27
- RE: [lwip-users] Sizes, Bill Auerbach, 2009/05/27
- RE: [lwip-users] Sizes, John Kennedy, 2009/05/27
- Re: RE: [lwip-users] Sizes, Simon Goldschmidt, 2009/05/28
- RE: RE: [lwip-users] Sizes,
John Kennedy <=
- RE: RE: [lwip-users] Sizes, Bill Auerbach, 2009/05/28