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Date: Sat, 25 Jan 2003 04:22:39 +1100
From: Nick Piggin <piggin@cyberone.com.au>
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To: Giuliano Pochini <pochini@shiny.it>
CC: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-kernel@alex.org.uk,
       Alex Tomas <bzzz@tmi.comex.ru>, Andrew Morton <akpm@digeo.com>,
       Oliver Xymoron <oxymoron@waste.org>
Subject: Re: 2.5.59-mm5
References: <XFMail.20030124180942.pochini@shiny.it>
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Giuliano Pochini wrote:

>>>An alternate approach might be to change the way the scheduler splits
>>>things. That is, rather than marking I/O read vs write and scheduling
>>>based on that, add a flag bit to mark them all sync vs async since
>>>that's the distinction we actually care about. The normal paths can
>>>all do read+sync and write+async, but you can now do things like
>>>marking your truncate writes sync and readahead async.
>>>
>
>>That will be worth investigating to see if the complexity is worth it.
>>I think from a disk point of view, we still want to split batches between
>>reads and writes. Could be wrong.
>>
>
>Yes, sync vs async is a better way to classify io requests than
>read vs write and it's more correct from OS point of view. IMHO
>it's not more complex then now. Just replace r/w with sy/as and
>it will work.
>
We probably wouldn't want to go that far as you obviously can
only merge reads with reads and writes with writes, a flag would
be fine. We have to get the basics working first though ;)

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