Re: [PATCH 3/4] mm, page_alloc: fix dirtyable highmem calculation
From: Johannes Weiner
Date: Wed Jul 13 2016 - 09:16:51 EST
On Wed, Jul 13, 2016 at 11:00:03AM +0100, Mel Gorman wrote:
> From: Minchan Kim <minchan@xxxxxxxxxx>
> Note from Mel: This may optionally be considered a fix to the mmotm patch
> but if so, please preserve credit for Minchan.
> When I tested vmscale in mmtest in 32bit, I found the benchmark was slow
> down 0.5 times.
> base node
> 1 global-1
> User 12.98 16.04
> System 147.61 166.42
> Elapsed 26.48 38.08
> With vmstat, I found IO wait avg is much increased compared to base.
> The reason was highmem_dirtyable_memory accumulates free pages and
> highmem_file_pages from HIGHMEM to MOVABLE zones which was wrong. With
> that, dirth_thresh in throtlle_vm_write is always 0 so that it calls
> congestion_wait frequently if writeback starts.
> With this patch, it is much recovered.
> base node fi
> 1 global-1 fix
> User 12.98 16.04 13.78
> System 147.61 166.42 143.92
> Elapsed 26.48 38.08 29.64
> Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
> Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>