Re: [PATCH] Remove set_migrateflags()

[Mel Gorman <mel@csn.ul.ie>]

On (14/01/08 11:29), Christoph Lameter didst pronounce:
> On Mon, 14 Jan 2008, Mel Gorman wrote:
> 
> > Grouping the radix nodes into the same TLB entries as the inode and dcaches
> > does appear to help performance a small amount on kernbench at least. Applying
> > this patch showed a performance difference on elapsed time between -4.45%
> > and 0.23% and between -0.36% and 0.28% on total CPU time which appears to
> > support that position.
> 
> Ahh... Okay.
> 
> > > And thus setting __GFP_RECLAIMABLE
> > > is a bit strange. We could set SLAB_RECLAIM_ACCOUNT on radix tree slab
> > > creation if we want those to be placed in the reclaimable section.
> > > Then we are sure that the radix tree slabs are consistently placed in the
> > > reclaimable section and then the radix tree slabs will also be accounted as
> > > such.
> > > 
> > 
> > What is there right now places the pages appropriately but should they really
> > be accounted for as such too? I know that marking them like that will
> > cause SLUB to treat them differently and I don't fully understand the
> > implications of that.
> 
> Marking them makes the slab allocators set GFP_RECLAIMABLE on all page 
> allocator allocations for the radix tree and it will also cause the 
> statistics to be update correspondingly. No other differences.
> 

Ok, great.

> > NAK for now. I'm still of the opinion that radix nodes should be marked
> > reclaimable because they are often cleaned up at the same time as slabs that
> > are really reclaimable.
> 
> Do another version of this patch setting SLAB_RECLAIM_ACCOUNT for the 
> radix tree?
> 

If you send me a version, I'll review and put it through the same tests.
I can roll the patch as well if you'd prefer.

Thanks.

-- 
Mel Gorman
Part-time Phd Student                          Linux Technology Center
University of Limerick                         IBM Dublin Software Lab

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