On Tue, Mar 01, 2022 at 09:16:18AM +0800, Huang, Ying wrote:
> Hi, Oscar,
Hi Huang Ying
> b. Make kswapd of the fast memory node to reclaim pages until the free
> pages are a little more than the high watermark (named as promo
> watermark). If we want to promote some hot pages from the slow
> memory to the fast memory, but the free pages of the fast memory
> node will become lower than the high watermark after promotion, we
> will wake up kswapd of the fast memory node to demote more cold
> pages in the fast memory node to the slow memory node firstly. This
> will free some extra space in the fast memory node, so the hot pages
> in the slow memory node can be promoted to the fast memory node.
What about this? Somehow it sounds clear to me.
"b. Define a new watermark called wmark_promo which is higher than wmark_high,
and have kswapd reclaiming pages until free pages reach such watermark.
The scenario is as follows: when we want to promote hot-pages from a slow
memory to a fast memory, but fast memory's free pages would go lower than
high watermark with such promotion, we wake up kswapd with wmark_promo
watermark in order to demote cold pages and free us up some space.
So, next time we want to promote hot-pages we might have a chance of
doing so."
But I am fine with your updated write up as well, so if you spin a new
version:
Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
--
Oscar Salvador
SUSE Labs
