Re: [PATCH] Scalable page cache

[Christoph Hellwig <hch@ns.caldera.de>]

Hi Ingo,

In article <Pine.LNX.4.33.0111262026120.15876-100000@localhost.localdomain> you wrote:
> On 26 Nov 2001, Momchil Velikov wrote:
>
>> Yep.  Folks on #kernelnewbies told me about it, when there were only
>> changes to ``shrink_cache'' left.  So, I decided to funish mine ;)
>
> ok :) A search on Google for 'scalable pagecache' brings you straight to
> our patch. I've uploaded the patch against 2.4.16 as well:
>
>   http://redhat.com/~mingo/smp-pagecache-patches/pagecache-2.4.16-A1
>
> this is a (tested) port of the patch to the latest VM.

This patch seems to have a number of interesting changes compared to
older versions.

 - do_generic_file_read() now takes an additional integer parameter,
   'nonblock'.  This one always is zero, though.  Why do you break
   the interface?
 - there is a new global function, flush_inode_pages().  It is not
   used at all.  What is this one supposed to do?
 - file_send_actor() is no more static in mm/filemap.c.  I'm perfectly
   fine with that as I will need that for the UnixWare sendv64 emulation
   in Linux-ABI, but again no user outside of filemap.c exists.
 - you change a number of parameters called 'offset' into 'index',
   this makes sense to me, but doesn't really belong into this diff..
 - due to the additional per-bucket spinlock the pagecache size
   dramatically increases.  Wouldn't it be a good idea to switch to
   bootmem allocation so very big machines still can have the full
   size, not limited by __get_free_pages failing?