On Thu, Feb 13, 2020 at 06:48:06PM -0800, Matthew Wilcox wrote: >On Fri, Feb 14, 2020 at 10:05:15AM +0800, Wei Yang wrote: >> On Wed, Feb 12, 2020 at 07:43:33AM +0000, Mel Gorman wrote: >> >Broadly speaking it was driven by cases whereby kswapd either a) fell >> >asleep prematurely and there were many stalls in direct reclaim before >> >kswapd recovered, b) stalls in direct reclaim immediately after kswapd went >> >to sleep or c) kswapd reclaimed for lower zones and went to sleep while >> >parallel tasks were direct reclaiming in higher zones or higher orders. >> >> Thanks for your explanation. I am trying to understand the connection between >> those cases and the behavior of kswapd. >> >> In summary, all three cases are related to direct reclaim, while happens in >> three different timing of kswapd: > >Reclaim performed by kswapd is the opposite of direct reclaim. Direct >reclaim is reclaim initiated by a task which is trying to allocate memory. >If a task cannot perform direct reclaim itself, it may ask kswapd to >attempt to reclaim memory for it. Not totally opposite, I think. They both reclaim some memory, while after direct reclaim, some freed memory will be allocated. Is this the difference you want to mention? -- Wei Yang Help you, Help me
