linux-kernel - Re: Change PAGE_SIZE from minimum 4k to 12k

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Message-ID: <20170525210855.3ca03356@alans-desktop>
Date:   Thu, 25 May 2017 21:08:55 +0100
From:   Alan Cox <gnomes@...rguk.ukuu.org.uk>
To:     Pavel Machek <pavel@....cz>
Cc:     Kevin McKinney <klmckinney1@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: Change PAGE_SIZE from minimum 4k to 12k

On Thu, 25 May 2017 19:05:26 +0200
Pavel Machek <pavel@....cz> wrote:

> On Tue 2017-05-16 11:27:08, Kevin McKinney wrote:
> > Hi Everyone,
> > 
> > Would it be possible to have a custom block device driver read/write
> > in increments of 12k instead of reading/writing data in 4k increments?
> > In other words, I would like to change the default page size on a
> > x86_64 platform (4.4.0 kernel) from 4k to 12k as the minimum page
> > size?  I understand I may have negative performance due to
> > fragmentation. Any help would be appreciated.
> > 
> > If this is the wrong mailing list, please let me know the right one to use.  
> 
> I won't say "no" but ammount of work neccessary is likely measured in
> man-years. Plus, hardware page size _is_ 4KB.

Or a few other much larger sizes. Not that it actually matters. You can
implement a larger software page size for a platform but it would still
neeed to be a power of two, and you'd have trouble running some existing
binaries for x86.

What problem are you *actually* trying to solve ?

Alan