Re: [RFC 0/8] Variable Order Page Cache

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From: Maxim Levitsky
Date: Thursday, April 19, 2007 - 4:58 pm

On Thursday 19 April 2007 19:35:04 Christoph Lameter wrote:
(ramfs).
general
mm
layers).

Hello,

This is exactly what I wanted some time ago,
Thank you very much, I was almost thinking of doing this myself 
(but decided that it is too difficult now for me and maybe doesn't worth the 
effort)

I want to point out on number of problems that this will solve (and reasons I 
wanted to do that)

First of all, today, packet writing on cd/dvd doesn't work well, it is very 
slow because 
now all file-systems are limited to 4k-barrier and cd/dvd can write only 
32k/64k packets.
This is why a pktcdvd was written and it emulates those 4k sectors by doing 
read/modify/write cycle
This cause a lot of seeks and read/writing switches and thus it is very slow.

By introducing a bigger that 4k page cache a dvd/cd can be divided is 64k/32k 
blocks that will be read an written freely
(Although dvd can read 2k  I don't think that reading a 64k block will hurt 
since most of time drive is busy seeking and locating a specific sector)

Now I thinking to implement this in an other way, I mean I want to teach udf 
filesystem to to packet writing on its own, bypassing disk cache (but not page 
cache)

Secondary 32/64k limitation is present of flash devices too, so they can 
benefit too, and I almost sure that future hard disks will use bigger block 
size too.

To summarize I want to tell that bigger pagesize will allow devices that have 
big hardware sectors to work fine in linux.

Best regards,
	Maxim Levitsky
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Messages in current thread:
[RFC 0/8] Variable Order Page Cache, Christoph Lameter, (Thu Apr 19, 9:35 am)
[RFC 1/8] Add order field to address_space struct, Christoph Lameter, (Thu Apr 19, 9:35 am)
[RFC 2/8] Basic allocation for higher order page cache pages, Christoph Lameter, (Thu Apr 19, 9:35 am)
[RFC 3/8] Flushing and zeroing higher order page cache pages, Christoph Lameter, (Thu Apr 19, 9:35 am)
[RFC 4/8] Enhance fallback functions in libs to support hi ..., Christoph Lameter, (Thu Apr 19, 9:35 am)
[RFC 5/8] Enhance generic_read/write to support higher ord ..., Christoph Lameter, (Thu Apr 19, 9:35 am)
[RFC 6/8] Account for pages in the page cache in terms of ..., Christoph Lameter, (Thu Apr 19, 9:35 am)
[RFC 7/8] Enhance ramfs to support higher order pages, Christoph Lameter, (Thu Apr 19, 9:35 am)
[RFC 8/8] Add some debug output, Christoph Lameter, (Thu Apr 19, 9:35 am)
Re: [RFC 6/8] Account for pages in the page cache in terms ..., Christoph Lameter, (Thu Apr 19, 10:52 am)
Re: [RFC 0/8] Variable Order Page Cache, Badari Pulavarty, (Thu Apr 19, 12:09 pm)
Re: [RFC 4/8] Enhance fallback functions in libs to suppor ..., Christoph Lameter, (Thu Apr 19, 12:10 pm)
Re: [RFC 0/8] Variable Order Page Cache, Andi Kleen, (Thu Apr 19, 12:11 pm)
Re: [RFC 0/8] Variable Order Page Cache, Christoph Lameter, (Thu Apr 19, 12:12 pm)
Re: [RFC 0/8] Variable Order Page Cache, Christoph Lameter, (Thu Apr 19, 12:15 pm)
Re: [RFC 0/8] Variable Order Page Cache, David Chinner, (Thu Apr 19, 3:42 pm)
Re: [RFC 0/8] Variable Order Page Cache, Maxim Levitsky, (Thu Apr 19, 4:58 pm)
Re: [RFC 0/8] Variable Order Page Cache, Christoph Lameter, (Thu Apr 19, 6:14 pm)
Re: [RFC 4/8] Enhance fallback functions in libs to suppor ..., Christoph Lameter, (Thu Apr 19, 6:15 pm)
Re: [RFC 0/8] Variable Order Page Cache, Christoph Lameter, (Thu Apr 19, 6:15 pm)
Re: [RFC 0/8] Variable Order Page Cache, William Lee Irwin III, (Thu Apr 19, 9:47 pm)
Re: [RFC 0/8] Variable Order Page Cache, Christoph Lameter, (Thu Apr 19, 10:27 pm)
Re: [RFC 0/8] Variable Order Page Cache, William Lee Irwin III, (Thu Apr 19, 11:22 pm)
Re: [RFC 0/8] Variable Order Page Cache, Jens Axboe, (Thu Apr 19, 11:32 pm)
Re: [RFC 0/8] Variable Order Page Cache, David Chinner, (Fri Apr 20, 12:48 am)
Re: [RFC 0/8] Variable Order Page Cache, David Chinner, (Fri Apr 20, 1:42 am)
Re: [RFC 0/8] Variable Order Page Cache, Mel Gorman, (Fri Apr 20, 7:14 am)
Re: [RFC 0/8] Variable Order Page Cache, Mel Gorman, (Fri Apr 20, 7:37 am)
Re: [RFC 7/8] Enhance ramfs to support higher order pages, William Lee Irwin III, (Fri Apr 20, 7:47 am)
Re: [RFC 4/8] Enhance fallback functions in libs to suppor ..., Christoph Lameter, (Fri Apr 20, 9:01 am)
Re: [RFC 3/8] Flushing and zeroing higher order page cache ..., Christoph Lameter, (Fri Apr 20, 9:15 am)
Re: [RFC 7/8] Enhance ramfs to support higher order pages, Christoph Lameter, (Fri Apr 20, 9:20 am)
Re: [RFC 0/8] Variable Order Page Cache, Christoph Lameter, (Fri Apr 20, 9:23 am)
Re: [RFC 7/8] Enhance ramfs to support higher order pages, Christoph Lameter, (Fri Apr 20, 9:30 am)
Re: [RFC 3/8] Flushing and zeroing higher order page cache ..., William Lee Irwin III, (Fri Apr 20, 9:51 am)
Re: [RFC 7/8] Enhance ramfs to support higher order pages, William Lee Irwin III, (Fri Apr 20, 10:11 am)
Re: [RFC 7/8] Enhance ramfs to support higher order pages, Christoph Lameter, (Fri Apr 20, 10:15 am)
Re: [RFC 7/8] Enhance ramfs to support higher order pages, William Lee Irwin III, (Fri Apr 20, 10:19 am)
Re: [RFC 7/8] Enhance ramfs to support higher order pages, Christoph Lameter, (Fri Apr 20, 10:57 am)
Re: [RFC 7/8] Enhance ramfs to support higher order pages, Christoph Lameter, (Fri Apr 20, 10:59 am)
Re: [RFC 7/8] Enhance ramfs to support higher order pages, Christoph Lameter, (Fri Apr 20, 11:01 am)
Re: [RFC 7/8] Enhance ramfs to support higher order pages, Christoph Lameter, (Fri Apr 20, 11:02 am)
Re: [RFC 4/8] Enhance fallback functions in libs to suppor ..., Christoph Lameter, (Fri Apr 20, 12:10 pm)
Re: [RFC 7/8] Enhance ramfs to support higher order pages, William Lee Irwin III, (Fri Apr 20, 12:21 pm)
Re: [RFC 0/8] Variable Order Page Cache, Andrew Morton, (Sat Apr 21, 3:18 pm)