From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Lee Revell <rlrevell@joe-job.com>
Cc: Hugh Dickins <hugh@veritas.com>, Ingo Molnar <mingo@elte.hu>,
Andrew Morton <akpm@osdl.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: More latency regressions with 2.6.11-rc4-RT-V0.7.39-02
Date: Thu, 24 Feb 2005 13:41:21 +1100 [thread overview]
Message-ID: <421D3ED1.9040409@yahoo.com.au> (raw)
In-Reply-To: <1109211897.4831.2.camel@krustophenia.net>
Lee Revell wrote:
> On Thu, 2005-02-24 at 12:29 +1100, Nick Piggin wrote:
>
>>Lee Revell wrote:
>>
>>>IIRC last time I really tested this a few months ago, the worst case
>>>latency on that machine was about 150us. Currently its 422us from the
>>>same clear_page_range code path.
>>>
>>
>>Well it should be pretty trivial to add a break in there.
>>I don't think it can get into 2.6.11 at this point though,
>>so we'll revisit this for 2.6.12 if the clear_page_range
>>optimisations don't get anywhere.
>>
>
>
> Agreed, it would be much better to optimize this away than just add a
> scheduling point. It seems like we could do this lazily.
>
Oh? What do you mean by lazy? IMO it is sort of implemented lazily now.
That is, we are too lazy to refcount page table pages in fastpaths, so
that pushes a lot of work to unmap time. Not necessarily a bad trade-off,
mind you. Just something I'm looking into.
next prev parent reply other threads:[~2005-02-24 2:43 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-02-23 18:07 More latency regressions with 2.6.11-rc4-RT-V0.7.39-02 Lee Revell
2005-02-23 19:16 ` Hugh Dickins
2005-02-23 19:36 ` Lee Revell
2005-02-23 20:06 ` Hugh Dickins
2005-02-23 20:10 ` Lee Revell
2005-02-23 20:30 ` Lee Revell
2005-02-23 21:03 ` Hugh Dickins
2005-02-23 22:14 ` Lee Revell
2005-02-23 23:52 ` PPC RT Patch john cooper
2005-02-24 4:20 ` Frank Rowand
2005-02-24 13:56 ` john cooper
2005-02-23 23:27 ` More latency regressions with 2.6.11-rc4-RT-V0.7.39-02 Nick Piggin
2005-02-24 1:03 ` Lee Revell
2005-02-24 1:29 ` Nick Piggin
2005-02-24 2:24 ` Lee Revell
2005-02-24 2:41 ` Nick Piggin [this message]
2005-02-24 3:03 ` Lee Revell
2005-02-23 20:53 ` Hugh Dickins
2005-02-23 22:13 ` Lee Revell
2005-02-24 4:56 ` Hugh Dickins
2005-02-24 6:32 ` Lee Revell
2005-02-24 8:26 ` Hugh Dickins
2005-02-25 3:30 ` Lee Revell
2005-02-25 5:58 ` Hugh Dickins
2005-02-25 15:02 ` Lee Revell
2005-02-23 19:52 ` Lee Revell
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