Re: [PATCH v3 0/5] Introduce MADV_COLD and MADV_PAGEOUT

[Kirill A. Shutemov]

On Thu, Jun 27, 2019 at 08:54:00PM +0900, Minchan Kim wrote:
> - Problem
> 
> Naturally, cached apps were dominant consumers of memory on the system.
> However, they were not significant consumers of swap even though they are
> good candidate for swap. Under investigation, swapping out only begins
> once the low zone watermark is hit and kswapd wakes up, but the overall
> allocation rate in the system might trip lmkd thresholds and cause a cached
> process to be killed(we measured performance swapping out vs. zapping the
> memory by killing a process. Unsurprisingly, zapping is 10x times faster
> even though we use zram which is much faster than real storage) so kill
> from lmkd will often satisfy the high zone watermark, resulting in very
> few pages actually being moved to swap.

Maybe we should look if we do The Right Thingâ at system-wide level before
introducing new API? How changing swappiness affects your workloads? What
is swappiness value in your setup?

-- 
 Kirill A. Shutemov