Re: [PATCH v0 1/2] perf: Add an option to ask for high order allocations for AUX buffers
From: Peter Zijlstra
Date: Wed Feb 13 2019 - 12:54:45 EST
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?