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From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Steven Pratt <slpratt@austin.ibm.com>
Cc: Andrew Morton <akpm@osdl.org>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH/RFC] Simplified Readahead
Date: Sat, 25 Sep 2004 02:16:54 +1000	[thread overview]
Message-ID: <41544876.4040302@yahoo.com.au> (raw)
In-Reply-To: <41543FE2.5040807@austin.ibm.com>

Steven Pratt wrote:
> Andrew Morton wrote:
> 
>> Steven Pratt <slpratt@austin.ibm.com> wrote:
>>  
>>
>>> would like to offer up an alternative simplified design which will 
>>> not only make the code easier to maintain,
>>>   
>>
>>
>> We won't know that until all functionality is in place.
>>  
>>
> Ok, but both you and Nick indicated that the queue congestion isn't 
> needed,

I would have thought that always doing the readahead would provide a
more graceful degradation, assuming the readahead algorithm is fairly
accurate, and copes with things like readahead thrashing (which we
hope is the case).

>> I do think we should skip the I/O for POSIX_FADV_WILLNEED against a
>> congested queue.  I can't immediately think of a good reason for skipping
>> the I/O for normal readahead.
>>  

I don't see why you should skip the readahead for FADVISE_WILLNEED
either. Presumably if someone needs this, they really need it. We
should aim for optimal behaviour when the apis are being used correctly...

  reply	other threads:[~2004-09-24 16:40 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-09-23 16:06 [PATCH/RFC] Simplified Readahead Steven Pratt
2004-09-23 22:14 ` Joel Schopp
2004-09-24  0:21 ` Nick Piggin
2004-09-24  2:42 ` Andrew Morton
2004-09-24 15:40   ` Steven Pratt
2004-09-24 16:16     ` Nick Piggin [this message]
2004-09-24 16:48       ` Steven Pratt
2004-09-24 22:05     ` Andrew Morton
2004-09-24 22:43       ` Steven Pratt
2004-09-24 23:01         ` Andrew Morton
2004-09-27 15:39           ` Steven Pratt
2004-09-27 19:26             ` Andrew Morton
2004-09-28 10:13               ` Jens Axboe
2004-09-24 22:55       ` Steven Pratt
2004-09-27 20:29         ` Ray Bryant
2004-09-27 21:04           ` Steven Pratt
2004-09-25  0:45       ` Nick Piggin
2004-09-25  1:01 ` Ram Pai
2004-09-25  6:07   ` Ram Pai
2004-09-27 15:30     ` Steven Pratt
2004-09-27 18:42       ` Ram Pai
2004-09-27 20:07         ` Steven Pratt
2004-09-29 18:46           ` Ram Pai
2004-09-29 22:33             ` Steven Pratt
2004-09-29 23:13               ` Andreas Dilger
2004-09-30  2:26                 ` Ram Pai
2004-09-30  5:29                   ` Andrew Morton
2004-09-30 20:20                 ` Stephen C. Tweedie
2004-09-30  1:12               ` Ram Pai
2004-10-01 21:02             ` Steven Pratt
2004-10-05 17:52               ` Ram Pai
     [not found] <372479081@toto.iv>
2004-09-24  5:00 ` Peter Chubb
2004-09-24 22:57   ` Steven Pratt

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