linux-kernel - Re: [PATCH v4 00/10] PCID and improved laziness

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Date:   Mon, 17 Jul 2017 10:57:15 +0100
From:   Mel Gorman <mgorman@...e.de>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Andy Lutomirski <luto@...nel.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org, Borislav Petkov <bp@...en8.de>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        Nadav Amit <nadav.amit@...il.com>,
        Rik van Riel <riel@...hat.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Arjan van de Ven <arjan@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH v4 00/10] PCID and improved laziness

On Wed, Jul 05, 2017 at 10:56:57AM +0200, Ingo Molnar wrote:
> 
> * Andy Lutomirski <luto@...nel.org> wrote:
> 
> > *** Ingo, even if this misses 4.13, please apply the first patch before
> > *** the merge window.
> 
> > Andy Lutomirski (10):
> >   x86/mm: Don't reenter flush_tlb_func_common()
> >   x86/mm: Delete a big outdated comment about TLB flushing
> >   x86/mm: Give each mm TLB flush generation a unique ID
> >   x86/mm: Track the TLB's tlb_gen and update the flushing algorithm
> >   x86/mm: Rework lazy TLB mode and TLB freshness tracking
> >   x86/mm: Stop calling leave_mm() in idle code
> >   x86/mm: Disable PCID on 32-bit kernels
> >   x86/mm: Add nopcid to turn off PCID
> >   x86/mm: Enable CR4.PCIDE on supported systems
> >   x86/mm: Try to preserve old TLB entries using PCID
> 
> So this series is really nice, and the first two patches are already upstream, and 
> I've just applied all but the final patch to tip:x86/mm (out of caution - I'm a wimp).
> 
> That should already offer some improvements and enables the CR4 bit - but doesn't 
> actually use the PCID hardware yet.
> 
> I'll push it all out when it passes testing.
> 
> If it's all super stable I plan to tempt Linus with a late merge window pull 
> request for all these preparatory patches. (Unless he objects that is. Hint, hint.)
> 
> Any objections?
> 

What was the final verdict here? I have a patch ready that should be layered
on top which will need a backport. PCID support does not appear to have
made it in this merge window so I'm wondering if I should send the patch
as-is for placement on top of Andy's work or go with the backport and
apply a follow-on patch after Andy's work gets merged.

Thanks.

-- 
Mel Gorman
SUSE Labs