linux-kernel - Re: [PATCH 0/3] TLB flush multiple pages per IPI v5

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Message-ID: <20150610172457.GH26425@suse.de>
Date:	Wed, 10 Jun 2015 18:24:57 +0100
From:	Mel Gorman <mgorman@...e.de>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Andi Kleen <andi@...stfloor.org>,
	Dave Hansen <dave.hansen@...el.com>,
	Ingo Molnar <mingo@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Rik van Riel <riel@...hat.com>,
	Hugh Dickins <hughd@...gle.com>,
	Minchan Kim <minchan@...nel.org>,
	H Peter Anvin <hpa@...or.com>, Linux-MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 0/3] TLB flush multiple pages per IPI v5

On Wed, Jun 10, 2015 at 09:42:34AM -0700, Linus Torvalds wrote:
> On Wed, Jun 10, 2015 at 9:17 AM, Linus Torvalds
> <torvalds@...ux-foundation.org> wrote:
> >
> > So anyway, I like the patch series. I just think that the final patch
> > - the one that actually saves the addreses, and limits things to
> > BATCH_TLBFLUSH_SIZE, should be limited.
> 
> Oh, and another thing:
> 
> Mel, can you please make that "struct tlbflush_unmap_batch" be just
> part of "struct task_struct" rather than a pointer?
> 

Yes, that was done earlier today based on Ingo's review so that the
allocation could be dealt with as a separate path at the end of the series.

> If you are worried about the cpumask size, you could use
> 
>       cpumask_var_t cpumask;
> 
> and
> 
>         alloc_cpumask_var(..)
> ...
>         free_cpumask_var(..)
> 
> for that.
> 
> That way, sane configurations never have the allocation cost.
> 

Ok, good point.  Patch 3 in my git tree ("mm: Dynamically allocate TLB
batch unmap control structure") does not do this but I'll look into doing
it before the release based on 4.2-rc1.

-- 
Mel Gorman
SUSE Labs
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