Re: O->A loan

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

hi,

i'm wondering why the following two are this drastically different.
was there configuration changes more than flipping DIAGNOSTIC?

        http://linbsd.org/yamt.png
        http://linbsd.org/yamt3.png

YAMAMOTO Takashi

> This is the same hardware.
> rmind had noticed in the lockstat output that fileassoc was being called
> on all unlink() operation. So I am rerunning the tests without fileassoc.
> 
> On Mon, 16 Jan 2012, YAMAMOTO Takashi wrote:
> 
>> Date: Mon, 16 Jan 2012 03:47:48 +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.
>> 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
>>
>