Re: [PATCH] Scalable page cache

Christoph Hellwig (hch@ns.caldera.de)
Mon, 26 Nov 2001 19:08:20 +0100


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?

-
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