On 5/21/21 3:28 AM, Mel Gorman wrote: > The vm.percpu_pagelist_fraction is used to increase the batch and high > limits for the per-cpu page allocator (PCP). The intent behind the sysctl > is to reduce zone lock acquisition when allocating/freeing pages but it has > a problem. While it can decrease contention, it can also increase latency > on the allocation side due to unreasonably large batch sizes. This leads > to games where an administrator adjusts percpu_pagelist_fraction on the > fly to work around contention and allocation latency problems. > > This series aims to alleviate the problems with zone lock contention while > avoiding the allocation-side latency problems. For the purposes of review, > it's easier to remove this sysctl now and reintroduce a similar sysctl > later in the series that deals only with pcp->high. > > Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> I despise working with percpu_pagelist_fraction. I usually just end up poking random numbers into it and then checking what the fallout looks like in /proc/zoneinfo is. Good riddance. Acked-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
