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* HugePages for MD's caches -- can this be done in modern kernel?
       [not found] <43d009740902061008p968268bj30a03c6f97139bbe@mail.gmail.com>
@ 2009-02-06 18:11 ` Igor Podlesny
       [not found] ` <c39d1fabb5aef8e2ed5158ad59802cf1.squirrel@neil.brown.name>
  1 sibling, 0 replies; 3+ messages in thread
From: Igor Podlesny @ 2009-02-06 18:11 UTC (permalink / raw)
  To: linux-raid; +Cc: neilb, H. Peter Anvin

	Hi!

	$(Subj) :-) Is it worth of efforts?

	P. S. Also, I deem there lots of structures in kernel that could
benefit from using HugePages.
	But this probably a q-n for another kernel list.

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^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: HugePages for MD's caches -- can this be done in modern kernel?
       [not found] ` <c39d1fabb5aef8e2ed5158ad59802cf1.squirrel@neil.brown.name>
@ 2009-02-06 19:27   ` Igor Podlesny
  2009-02-06 20:16     ` NeilBrown
  0 siblings, 1 reply; 3+ messages in thread
From: Igor Podlesny @ 2009-02-06 19:27 UTC (permalink / raw)
  To: NeilBrown; +Cc: linux-raid

2009/2/7 NeilBrown <neilb@suse.de>:
> On Sat, February 7, 2009 5:08 am, Igor Podlesny wrote:
>>    Hi!
>>
>>    $(Subj). :-)
>>
>>    P. S. Also, I deem there lots of structures in kernel that could
>> benefit
>> from using HugePages. But this probably a q-n for another kernel list.
>
> I have only a vague idea what HugePages are and it is not at all clear to
> me why you would want to use them for the MD cache.   I assume you are
>
	HugePages requires less TBL entries so they better fit for large
buffers, as far as I understand.

	http://unixfoo.blogspot.com/2007/10/hugepages.html
	http://linux-mm.org/HugePagesArticles

> talking about MD/RAID456 as that is the only place we use a cache.
>
	Yeah, "stripe_cache_size" setting.
>
> Maybe if you could explain what you are thinking....
>
	Yeah, hope this would suffice.

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^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: HugePages for MD's caches -- can this be done in modern kernel?
  2009-02-06 19:27   ` Igor Podlesny
@ 2009-02-06 20:16     ` NeilBrown
  0 siblings, 0 replies; 3+ messages in thread
From: NeilBrown @ 2009-02-06 20:16 UTC (permalink / raw)
  To: for.poige+linux; +Cc: linux-raid

On Sat, February 7, 2009 6:27 am, Igor Podlesny wrote:
> 2009/2/7 NeilBrown <neilb@suse.de>:
>> On Sat, February 7, 2009 5:08 am, Igor Podlesny wrote:
>>>    Hi!
>>>
>>>    $(Subj). :-)
>>>
>>>    P. S. Also, I deem there lots of structures in kernel that could
>>> benefit
>>> from using HugePages. But this probably a q-n for another kernel list.
>>
>> I have only a vague idea what HugePages are and it is not at all clear
>> to
>> me why you would want to use them for the MD cache.   I assume you are
>>
> 	HugePages requires less TBL entries so they better fit for large
> buffers, as far as I understand.
>
> 	http://unixfoo.blogspot.com/2007/10/hugepages.html
> 	http://linux-mm.org/HugePagesArticles
>
>> talking about MD/RAID456 as that is the only place we use a cache.
>>
> 	Yeah, "stripe_cache_size" setting.
>>
>> Maybe if you could explain what you are thinking....
>>
> 	Yeah, hope this would suffice.

Not really, no.
md does not use "large buffers",  Just lots of little buffers.

NeilBrown


^ permalink raw reply	[flat|nested] 3+ messages in thread

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2009-02-06 18:11 ` HugePages for MD's caches -- can this be done in modern kernel? Igor Podlesny
     [not found] ` <c39d1fabb5aef8e2ed5158ad59802cf1.squirrel@neil.brown.name>
2009-02-06 19:27   ` Igor Podlesny
2009-02-06 20:16     ` NeilBrown

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