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 <redacted>

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@linux.intel.com>