On 15/08/2023 19:28, Jakub Kicinski wrote:

On Tue, 15 Aug 2023 19:20:31 +0100 Vadim Fedorenko wrote:

quoted

quoted

quoted

+	ret = xa_alloc(&dpll_device_xa, &dpll->id, dpll, xa_limit_16b,
+		       GFP_KERNEL);

Why only 16b and why not _cyclic?

I cannot image systems with more than 65k of DPLL devices. We don't
store any id's of last used DPLL device, so there is no easy way to
restart the search from the last point. And it's not a hot path to
optimize it.

I think this gets used under the xa_lock() so you can just add a static
variable inside the function to remember previous allocation.

I don't expect >64k devices either, obviously, but what are we saving
by not allowing the full u32 range?

I don't see any benefits for either _cyclic or u32 range, but if you 
insist I can change it.

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