Re: [reiserfs-dev] Re: Ext2 directory index: ALS paper and benchmarks

[Andrew Morton <akpm@zip.com.au>]

Daniel Phillips wrote:
> 
> On December 7, 2001 07:32 pm, Andrew Morton wrote:
> > Daniel Phillips wrote:
> > >
> > > Because Ext2 packs multiple entries onto a single inode table block, the
> > > major effect is not due to lack of readahead but to partially processed
> > > inode table blocks being evicted.
> >
> > Inode and directory lookups are satisfied direct from the icache/dcache,
> > and the underlying fs is not informed of a lookup, which confuses the VM.
> >
> > Possibly, implementing a d_revalidate() method which touches the
> > underlying block/page when a lookup occurs would help.
> 
> Very interesting point, the same thing happens with file index blocks vs page
> cache accesses.  You're suggesting we need some kind of mechanism for
> propagating hits on cache items, either back to the underlying data or the
> information used to regenerate the cache items.

Not just to regenerate, but in the case of inodes: to write them back.  

We have situations in which sync_unlocked_inodes() stalls badly,
because it keeps on doing reads.

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