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From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Shaohua Li <shaohua.li@intel.com>
Cc: lkml <linux-kernel@vger.kernel.org>, Andrew Morton <akpm@osdl.org>
Subject: Re: [PATCH] less tlb flush in unmap_vmas
Date: Wed, 22 Mar 2006 15:52:59 +1100	[thread overview]
Message-ID: <4420D82B.6080504@yahoo.com.au> (raw)
In-Reply-To: <1142995088.11430.34.camel@sli10-desk.sh.intel.com>

Shaohua Li wrote:

>In unmaping region, if current task doesn't need reschedule, don't do a
>tlb_finish_mmu. This can reduce some tlb flushes.
>
>In the lmbench tests, this patch gives 2.1% improvement on exec proc
>item and 4.2% on sh proc item.
>
>

The problem with this is that by the time we _do_ determine that a
reschedule is needed, we might have built up a huge amount of work
to do (which can probably be as much if not more exensive per-page
as the unmapping), so scheduling latency can still be unacceptable
so I'm afraid I don't think we can include this patch.

One option I've been looking into is my "mmu gather in-place" that
never needs extra tlb flushes and is always preemptible... so that
may be a way forward.

---

Send instant messages to your online friends http://au.messenger.yahoo.com 

  reply	other threads:[~2006-03-22  4:53 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-03-22  2:38 [PATCH] less tlb flush in unmap_vmas Shaohua Li
2006-03-22  4:52 ` Nick Piggin [this message]
2006-03-22  7:15   ` Chen, Kenneth W
2006-03-22  7:30     ` Nick Piggin
2006-03-22  7:44       ` Chen, Kenneth W
2006-03-22 10:13         ` Nick Piggin
2006-03-27  5:01         ` Lee Revell

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