On Mon, Oct 31, 2022 at 11:37:35AM +0800, Chen Wandun wrote: > > > > As is, the patch could result in a batch request of 0 and > > > I foget this, the patch need some improve, thanks. > > > > > > > fall through to allocating from the zone list anyway defeating the > > > > purpose of the PCP allocator and probably regressing performance in some > > > > csaes. > > > Same as I understand???how about set high/batch for each order in pcplist??? > > Using anything would than (X >> order) consumes storage. Even if storage > > was to be used, selecting a value per-order would be impossible because > > the correct value would depend on frequency of requests for each order. > > That can only be determined at runtime and the cost of determining the > > value would likely exceed the benefit. > > Can we set a experience value for pcp batch for each order during init > stage? I'm not sure what you mean by "experience value" but maybe you meant experimental value? > If so we can make accurately control for pcp size. Nowdays, the size of each > order in pcp list is full of randomness. I dont konw which scheme is better > for performance. > It is something that could be experimented with but the main question is -- what should those per-order values be? One option would be to enforce pcp->high for all high-order values except THP if THP is enabled. That would limit some of the issues with pcp->high being exceeded as even if two THPs are refilled, one of them is allocated immediately. I wasn't convinced it was necessary when implementing high-order PCP support but it could be evaluated. -- Mel Gorman SUSE Labs
