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Date: Wed, 12 Nov 2003 19:31:24 -0800
From: Andrew Morton <akpm@osdl.org>
To: Jack Steiner <steiner@sgi.com>
Cc: davidm@hpl.hp.com, linux-ia64@vger.kernel.org,
       linux-kernel@vger.kernel.org
Subject: Re: Inefficient TLB flushing
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Jack Steiner <steiner@sgi.com> wrote:
>
> > Either that, or add a new interface function
>  > 
>  > 	int mmu_gather_is_full_mm(mmu_gather *tlb);
>  > 
>  > and use it...
>  > 
> 
>  How implementation independent should it be? Currently, there is only one
>  field in the mmu_gather structure that must be preserved. However, if we
>  want to make the interface truly implementation independent, it seems
>  like we should define something like:
> 
>  	if (need_resched()) {
>  		struct mmu_gather_state state;
>  		tlb_mmu_gather_save_state(*tlbp, &state);
>  		tlb_finish_mmu(*tlbp, tlb_start, start);
>  		...
>  		*tlbp = tlb_mmu_gather_restore_state(&state);
>  	}
> 
>  Is this overkill?

Think so ;) The `full_mm_flush' boolean is the only state thing we can pass
into tlb_gather_mmu anyway.

> 
>  Should we use the patch given above for 2.6.0 & replace it with an implementation 
>  independent interface for 2.6.1?

Just the little wrapper which doesn't assume the presence of
mmu_gather.full_mm should suffice.