From: Nick Piggin <nickpiggin@yahoo.com.au>
To: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Cc: "Li, Shaohua" <shaohua.li@intel.com>,
"'lkml'" <linux-kernel@vger.kernel.org>,
"'Andrew Morton'" <akpm@osdl.org>,
Hugh Dickins <hugh@veritas.com>
Subject: Re: [PATCH] less tlb flush in unmap_vmas
Date: Wed, 22 Mar 2006 21:13:12 +1100 [thread overview]
Message-ID: <44212338.3050309@yahoo.com.au> (raw)
In-Reply-To: <200603220744.k2M7iBg05206@unix-os.sc.intel.com>
Chen, Kenneth W wrote:
> Nick Piggin wrote on Tuesday, March 21, 2006 11:30 PM
>
>>Well mmu_gather uses a per-cpu data structure and is non preemptible,
>>which I guess is one of the main reasons why we have this preemption
>>here.
>>
>>You're right that another good reason would be ptl lock contention,
>>however I don't think that alleviating that problem alone would allow
>>longer mmu_gather scheduling latencies, because the longest latency
>>is still the mmu_gather <--> mmu_finish span.
>
>
> OK, I think it would be beneficial to take a latency measurement again,
> just to see how it perform now a day. The dynamics might changed.
>
Well I wouldn't argue against further investigation or fine tuning
the present code, however also remember that the way of unconditionally
finishing the mmu_gather that the patch is aimed to prevent never
actually lowered ptl hold times itself.
--
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com
next prev parent reply other threads:[~2006-03-22 11:12 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
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 [this message]
2006-03-27 5:01 ` Lee Revell
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