Re: [RFC][PATCH 0/6] Another go at speculative page faults

From: Davidlohr Bueso
Date: Wed Oct 22 2014 - 03:35:21 EST


On Mon, 2014-10-20 at 23:56 +0200, Peter Zijlstra wrote:
> Hi,
>
> I figured I'd give my 2010 speculative fault series another spin:
>
> https://lkml.org/lkml/2010/1/4/257
>
> Since then I think many of the outstanding issues have changed sufficiently to
> warrant another go. In particular Al Viro's delayed fput seems to have made it
> entirely 'normal' to delay fput(). Lai Jiangshan's SRCU rewrite provided us
> with call_srcu() and my preemptible mmu_gather removed the TLB flushes from
> under the PTL.
>
> The code needs way more attention but builds a kernel and runs the
> micro-benchmark so I figured I'd post it before sinking more time into it.
>
> I realize the micro-bench is about as good as it gets for this series and not
> very realistic otherwise, but I think it does show the potential benefit the
> approach has.
>
> (patches go against .18-rc1+)

I think patch 2/6 is borken:

error: patch failed: mm/memory.c:2025
error: mm/memory.c: patch does not apply

and related, as you mention, I would very much welcome having the
introduction of 'struct faut_env' as a separate cleanup patch. May I
suggest renaming it to fault_cxt?

Thanks,
Davidlohr

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