Re: partially encrypted filesystem

[Pat LaVarre]

> ... but I don't think Linux has very good support for filesystems that
> want to drop 64 pages into the page cache when the VM/VFS only asked
> for one.
> 
> If it did, that would allow ext2/3 to grow block sizes beyond the
> current 4k limit on i386, which would be a good thing to do.  Or
> perhaps we just need to bite the bullet and increase PAGE_CACHE_SIZE
> to something bigger, like 64k.  People are going to want that on
> 32-bit systems soon anyway.

Issue now yes.  Three pieces of evidence:

1)

I hear CD-RW commonly report 64 KiB per write block, DVD-RAM/ DVD+RW
often report 32 KiB per write block.

2)

http://marc.theaimsgroup.com/?l=linux-scsi&m=106700651518749
Subject:  Re: aligned /dev/scd$n reads less rare how
Date: 2003-10-24 14:41:16
is me saying a naive lk 2.6 test like `dd if=/dev/scd0 bs=1M` doesn't
yet improve read thruput by polite alignment, much less improve write
thruput by polite alignment.

Specifically I see we lose alignment in the second cdb and following,
til the end of the disc.

3)

http://marc.theaimsgroup.com/?l=linux-scsi&m=107004995921559
Subject: cdrom sr ide-cd - CDC_WR, 1999 op x46 GPCMD_GET_CONFIGURATION
Date: 2003-11-28 20:05:03
is me saying cdrom.ko does not yet fetch via SCSI over whatever (USB2HS/
ATAPIUDMA133/ 1394a/ ...) the 1999 ANSI T10 standard plug 'n play
descriptor that distinguishes the 32/64 KiB bytes per write block from
the 2 KiB bytes per read block.  (Relevant patches appear incomplete,
nearby.)

Pat LaVarre


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