linux-kernel - Re: [PATCH v2] MIPS: Take in account load hazards for HI/LO restoring

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Message-ID: <ZjTdvUDL01XV39Lm@alpha.franken.de>
Date: Fri, 3 May 2024 14:51:09 +0200
From: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
To: Siarhei Volkau <lis8215@...il.com>
Cc: linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] MIPS: Take in account load hazards for HI/LO restoring

On Tue, Apr 30, 2024 at 06:45:58PM +0300, Siarhei Volkau wrote:
> MIPS CPUs usually have 1 to 4 cycles load hazards, thus doing load
> and right after move to HI/LO will usually stall the pipeline for
> significant amount of time. Let's take it into account and separate
> loads and mthi/lo in instruction sequence.
> 
> The patch uses t6 and t7 registers as temporaries in addition to t8.
> 
> The patch tries to deal with SmartMIPS, but I know little about and
> haven't tested it.
> 
> Changes in v2:
> - clear separation of actions for SmartMIPS and pre-MIPSR6.
> 
> Signed-off-by: Siarhei Volkau <lis8215@...il.com>
> ---
>  arch/mips/include/asm/stackframe.h | 19 +++++++++++--------
>  1 file changed, 11 insertions(+), 8 deletions(-)
> 

applied to mips-next.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]