Re: O->A loan

[yamt%mwd.biglobe.ne.jp@localhost (YAMAMOTO Takashi)]

hi,

thanks.
is this on a different hardware from the previous one?

YAMAMOTO Takashi

> 
> Hello Yamamoto-san
> 
> I have run dbench on ufs/wapbl with diagnostics disabled.
> http://linbsd.org/yamt3.png
> 
> 
> On Thu, 12 Jan 2012, YAMAMOTO Takashi wrote:
> 
>> Date: Thu, 12 Jan 2012 03:31:59 +0000 (UTC)
>> From: YAMAMOTO Takashi <yamt%mwd.biglobe.ne.jp@localhost>
>> To: jaimef%mauthesis.com@localhost
>> Cc: chuq%chuq.com@localhost, tech-kern%netbsd.org@localhost
>> Subject: Re: O->A loan
>> 
>> hi,
>>
>>> I did not remove DIAGNOSTIC.
>>> Would you like me to rerun without DIAGNOSTIC?
>>
>> yes, please.
>>
>> YAMAMOTO Takashi
>>
>>> On Thu, 12 Jan 2012, YAMAMOTO Takashi wrote:
>>>
>>>> Date: Thu, 12 Jan 2012 03:14:33 +0000 (UTC)
>>>> From: YAMAMOTO Takashi <yamt%mwd.biglobe.ne.jp@localhost>
>>>> To: jaimef%mauthesis.com@localhost
>>>> Cc: chuq%chuq.com@localhost, tech-kern%netbsd.org@localhost
>>>> Subject: Re: O->A loan
>>>>
>>>> hi,
>>>>
>>>> thanks for benchmark!
>>>>
>>>> was it without DIAGNOSTIC?
>>>>
>>>> YAMAMOTO Takashi
>>>>
>>>>> Hello Yamamoto-san,
>>>>>
>>>>> I ran dbench on the same system with yamt-pagecache, yamt-pagecache
>>>>> without a-o loan, and yamt-pagecache-base3.
>>>>> http://linbsd.org/yamt.png
>>>>> The tests were run three times on each kernel and the results were
>>>>> consistent between reboots/runs.
>>>>>
>>>>> Thanks.
>>>>>
>>>>> On Tue, 27 Dec 2011, YAMAMOTO Takashi wrote:
>>>>>
>>>>>> Date: Tue, 27 Dec 2011 02:53:29 +0000 (UTC)
>>>>>> From: YAMAMOTO Takashi <yamt%mwd.biglobe.ne.jp@localhost>
>>>>>> To: chuq%chuq.com@localhost
>>>>>> Cc: tech-kern%netbsd.org@localhost
>>>>>> Subject: Re: O->A loan
>>>>>>
>>>>>> hi,
>>>>>>
>>>>>> i made read with O->A loaning work for easy cases (ie. no locking 
>>>>>> difficulty)
>>>>>> on yamt-pagecache branch so that someone interested can benchmark.
>>>>>>
>>>>>> YAMAMOTO Takashi
>>>>>>
>>>>>>> hi,
>>>>>>>
>>>>>>>> On Tue, Nov 29, 2011 at 06:38:27AM +0000, YAMAMOTO Takashi wrote:
>>>>>>>>> O->A loaned pages installed on the user address space would have a 
>>>>>>>>> different
>>>>>>>>> owner than the usual map->entry.uvm_obj.
>>>>>>>>> although it was not a problem when you wrote this patch, at least some
>>>>>>>>> non-mechanical changes would be required after the recent locking
>>>>>>>>> changes in this area.  namely, uvm_map_lock_entry etc now assumes that
>>>>>>>>> any pages mapped in a map entry belong to either the entry's amap or
>>>>>>>>> underlying object.
>>>>>>>>
>>>>>>>> ok, I didn't think it would be entirely mechanical.  :-)
>>>>>>>>
>>>>>>>> what if the O->A loan code also changed the entry's uvm_obj to be the 
>>>>>>>> vnode
>>>>>>>> that the pages really belong to?  if the loan range in the amap is 
>>>>>>>> fully
>>>>>>>> populated (which it is in this context) then that shouldn't affect the
>>>>>>>> logical contents of the entry, it would just cause anyone locking the 
>>>>>>>> entry
>>>>>>>> to also lock the vnode.  if the range of the loan is smaller than the
>>>>>>>> range of the entry, we could split the entry.  do you think that would 
>>>>>>>> work?
>>>>>>>
>>>>>>> it might work, but i have some concerns:
>>>>>>> - entry fragmentation
>>>>>>> - the extra uobj reference keeps the file even after unlink
>>>>>>>
>>>>>>> YAMAMOTO Takashi
>>>>>>>
>>>>>>>>
>>>>>>>> -Chuck