Re: [PATCH v0 1/2] perf: Add an option to ask for high order allocations for AUX buffers

[Peter Zijlstra]

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?