On Wed, Dec 07, 2016 at 10:40:47AM -0600, Christoph Lameter wrote: > On Wed, 7 Dec 2016, Mel Gorman wrote: > > > Which is related to the fundamentals of fragmentation control in > > general. At some point there will have to be a revisit to get back to > > the type of reliability that existed in 3.0-era without the massive > > overhead it incurred. As stated before, I agree it's important but > > outside the scope of this patch. > > What reliability issues are there? 3.X kernels were better in what > way? Which overhead are we talking about? >
3.0-era kernels had better fragmentation control, higher success rates at allocation etc. I vaguely recall that it had fewer sources of high-order allocations but I don't remember specifics and part of that could be the lack of THP at the time. The overhead was massive due to massive stalls and excessive reclaim -- hours to complete some high-allocation stress tests even if the success rate was high. -- Mel Gorman SUSE Labs
