On Mon, Feb 21, 2022 at 04:45:28PM +0800, Huang Ying wrote: > 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). Then, if the free pages of the fast memory node reaches > high watermark, and some hot pages need to be promoted, kswapd of the > fast memory node will be waken up to demote more cold pages in the > fast memory node to the slow memory node. 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. The patch looks good to me, but I think I might be confused by the wording here. IIUC, we define a new wmark (wmark_promo) which is higher than wmark_high. When we cannot migrate a page to another numa node because it has less than wmark_high free pages, we wake up kswapd, and we keep reclaiming until we either have mark_promo pages free when NUMA_BALANCING_MEMORY_TIERING, or mark_high pages free. Is that right? Because above you say "Then, if the free pages of the fast memory node reaches high watermark, and some hot pages need to be promoted..." but that should read promo watermark instead? Am I missing something? -- Oscar Salvador SUSE Labs
