On Wed, Feb 13, 2019 at 06:54:34PM +0100, Peter Zijlstra wrote: > On Wed, Feb 13, 2019 at 05:47:56PM +0000, Mel Gorman wrote: > > If there is a tangiable performance benefit from using contiguous regions > > then I would suggest optimistically allocating them with appropriate > > GFP flags to avoid large latencies at startup time and fall back if > > necessary. > > Right; the code does the fallback thing. It successively tries smaller > order allocations until 0-order fails. > > It currently uses: > > #define PERF_AUX_GFP (GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN | > __GFP_NORETRY) > > Is that what you could consider appropriate?
Yeah, spot on. Conceivably the semantics of __GFP_NORETY will change a little at some point in the next year but not in any way I'd consider harmful (depends on how THP and locality discussions go). Even *if* we did something harmful, there will be complaints before it's problematic. -- Mel Gorman SUSE Labs
