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From: Martin Schwidefsky <schwidefsky@de.ibm.com>
To: Hugh Dickins <hugh@veritas.com>
Cc: akpm@linux-foundation.org, peterz@infradead.org,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [patch 1/5] avoid tlb gather restarts.
Date: Wed, 04 Jul 2007 09:37:51 +0200	[thread overview]
Message-ID: <1183534671.1208.22.camel@localhost> (raw)
In-Reply-To: <Pine.LNX.4.64.0707031829390.2111@blonde.wat.veritas.com>

On Tue, 2007-07-03 at 18:42 +0100, Hugh Dickins wrote:
> > If need_resched() is false in the inner loop of unmap_vmas it is
> > unnecessary to do a full blown tlb_finish_mmu / tlb_gather_mmu for
> > each ZAP_BLOCK_SIZE ptes. Do a tlb_flush_mmu() instead. That gives
> > architectures with a non-generic tlb flush implementation room for
> > optimization. The tlb_flush_mmu primitive is a available with the
> > generic tlb flush code, the ia64_tlb_flush_mm needs to be renamed
> > and a dummy function is added to arm and arm26.
> > 
> > Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
> 
> Acked-by: Hugh Dickins <hugh@veritas.com>
> 
> (Looking at it, I see that we could argue that there ought to be a
> need_resched() etc. check after your tlb_flush_mmu() in unmap_vmas,
> in case it's spent a long while in there on some arches; but I don't
> think we have the ZAP_BLOCK_SIZE tuned with any great precision, and
> you'd at worst be doubling the latency there, so let's not worry
> about it.  I write this merely in order to reserve myself an
> "I told you so" if anyone ever notices increased latency ;)

Hmm, we'd have to repeat the longish if statement to make sure we don't
miss a cond_resched after tlb_flush_mmu. I'd rather not do that.

-- 
blue skies,
  Martin.

"Reality continues to ruin my life." - Calvin.



  reply	other threads:[~2007-07-04  7:35 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-07-03 11:18 [patch 0/5] some mm improvements + s390 tlb flush Martin Schwidefsky
2007-07-03 11:18 ` [patch 1/5] avoid tlb gather restarts Martin Schwidefsky
2007-07-03 17:42   ` Hugh Dickins
2007-07-04  7:37     ` Martin Schwidefsky [this message]
2007-07-16  6:20   ` Andrew Morton
2007-07-03 11:18 ` [patch 2/5] remove ptep_establish Martin Schwidefsky
2007-07-03 11:18 ` [patch 3/5] remove ptep_test_and_clear_dirty and ptep_clear_flush_dirty Martin Schwidefsky
2007-07-03 11:18 ` [patch 4/5] move mm_struct and vm_area_struct Martin Schwidefsky
2007-07-03 11:18 ` [patch 5/5] s390 tlb flush fix Martin Schwidefsky
2007-07-03 18:58   ` Hugh Dickins
2007-07-04  7:34     ` Martin Schwidefsky
  -- strict thread matches above, loose matches on Subject: below --
2007-06-29 13:55 [patch 0/5] Various mm improvements Martin Schwidefsky
2007-06-29 13:55 ` [patch 1/5] avoid tlb gather restarts Martin Schwidefsky
2007-06-29 18:56   ` Hugh Dickins
2007-06-29 21:19     ` Martin Schwidefsky
2007-06-30 13:16       ` Hugh Dickins

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