linux-kernel - Re: [RFC 0/8] Cpuset aware writeback

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Date:	Sat, 21 Apr 2007 01:15:25 -0700
From:	Ethan Solomita <solo@...gle.com>
To:	Christoph Lameter <clameter@....com>
CC:	akpm@...l.org, Paul Menage <menage@...gle.com>,
	linux-kernel@...r.kernel.org,
	Nick Piggin <nickpiggin@...oo.com.au>, linux-mm@...ck.org,
	Andi Kleen <ak@...e.de>, Paul Jackson <pj@....com>,
	Dave Chinner <dgc@....com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Subject: Re: [RFC 0/8] Cpuset aware writeback

Christoph Lameter wrote:
> On Fri, 20 Apr 2007, Ethan Solomita wrote:
>
>   
>> cpuset_write_dirty_map.htm
>>
>>    In __set_page_dirty_nobuffers() you always call cpuset_update_dirty_nodes()
>> but in __set_page_dirty_buffers() you call it only if page->mapping is still
>> set after locking. Is there a reason for the difference? Also a question not
>> about your patch: why do those functions call __mark_inode_dirty() even if the
>> dirty page has been truncated and mapping == NULL?
>>     
>
> If page->mapping has been cleared then the page was removed from the 
> mapping. __mark_inode_dirty just dirties the inode. If a truncation occurs 
> then the inode was modified.
>   

    You didn't address the first half. Why do the buffers() and 
nobuffers() act differently when calling cpuset_update_dirty_nodes()?

>> cpuset_write_throttle.htm
>>
>>    I noticed that several lines have leading spaces. I didn't check if other
>> patches have the problem too.
>>     
>
> Maybe download the patches? How did those strange .htm endings get 
> appended to the patches?
>   

    Something weird with Firefox, but instead of jumping on me did you 
consider double checking your patches? I just went back, found the text 
versions, and the spaces are still there.e.g.:

+  	unsigned long dirtyable_memory;


>>    In get_dirty_limits(), when cpusets are configd you don't subtract highmen
>> the same way that is done without cpusets. Is this intentional?
>>     
>
> That is something in flux upstream. Linus changed it recently. Do it one 
> way or the other.
>   

    Exactly -- your patch should be consistent and do it the same way as 
whatever your patch is built against. Your patch is built against a 
kernel that subtracts off highmem. "Do it..." are you handing off the 
patch and are done with it?

>>    It seems that dirty_exceeded is still a global punishment across cpusets.
>> Should it be addressed?
>>     
>
> Sure. It would be best if you could place that somehow in a cpuset.
>   

    Again it sounds like you're handing them off. I'm not objecting I 
just hadn't understood that.
    -- Ethan

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