On Fri, Jul 29, 2011 at 11:23:10PM +0800, Alex Shi wrote: > In commit 215ddd66, Mel Gorman said kswapd is better to sleep after a > unsuccessful balancing if there is tighter reclaim request pending in > the balancing. In this scenario, the 'order' and 'classzone_idx' > that are checked for tighter request judgment is incorrect, since they > aren't the one kswapd should read from new pgdat, but the last time pgdat > value for just now balancing. Then kswapd will skip try_to_sleep func > and rebalance the last pgdat request. It's not our expected behavior. > > So, I added new variables to distinguish the returned order/classzone_idx > from last balancing, that can resolved above issue in that scenario. > I'm afraid this changelog is very difficult to read and I do not see what problem you are trying to solve and I do not see what this patch might solve. When balance_pgdat() returns with a lower classzone or order, the values stored in pgdat are not re-read and instead it tries to go to sleep based on the starting request. Something like; 1. Read pgdat request A (classzone_idx, order) 2. balance_pgdat() 3. During pgdat, a new pgdat request B (classzone_idx, order) is placed 4. balance_pgdat() returns but failed so classzone_idx is lower 5. Try to sleep based on pgdat request A i.e. pgdat request B is not read and there is a comment explaining why pgdat request B is not read after balance_pgdat() fails. This patch adds some variables that might improve the readability for some people but otherwise I can't see what problem is being fixed. What did I miss? -- Mel Gorman SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>