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From: Ralf Baechle <ralf@linux-mips.org>
To: "Maciej W. Rozycki" <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org, Paul Gortmaker <paul.gortmaker@windriver.com>
Subject: Re: MIPS: Get rid of branches to .subsections.
Date: Mon, 23 Aug 2010 11:12:57 +0100	[thread overview]
Message-ID: <20100823101257.GA19171@linux-mips.org> (raw)
In-Reply-To: <alpine.LFD.2.00.1008230139480.900@eddie.linux-mips.org>

On Mon, Aug 23, 2010 at 01:54:24AM +0100, Maciej W. Rozycki wrote:

> > By rewriting the loop around all simple LL/SC blocks to C we reduce reduce
> > the amount of inline assembler and at the same time allow GCC to often
> > fill the branch delay slots with something sensible or whever else clever
> > optimization it may have up in its sleeve.
> 
>  Are you sure it won't reorder anything there that actually relies on the 
> atomic access to have succeeded?  I suggest adding barrier() after the 
> loop.

None of the things that were touched by the code had any barrier
functionality  Some of the functions such as atomic_add don't provide
memory barriers but where needed a barrier was always provided by C code
near the end of the function, for example in atomic_add_return.

  Ralf

  reply	other threads:[~2010-08-23 10:13 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-08-18 12:43 MIPS: Get rid of branches to .subsections Ralf Baechle
2010-08-18 13:25 ` Sergei Shtylyov
2010-08-18 13:42   ` Ralf Baechle
2010-08-18 13:33 ` Matt Fleming
2010-08-23  0:54 ` Maciej W. Rozycki
2010-08-23 10:12   ` Ralf Baechle [this message]
2010-08-23 11:25     ` Maciej W. Rozycki

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