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mlx4_core: Roll back round robin bitmap allocation commit for CQs, SRQs, and MPTs
Commit f4ec9e95 "mlx4_core: Change bitmap allocator to work in round-robin fashion" introduced round-robin allocation (via bitmap) for all resources which allocate via a bitmap. Round robin allocation is desirable for mcgs, counters, pd's, UARs, and xrcds. These are simply numbers, with no involvement of ICM memory mapping. Round robin is required for QPs, since we had a problem with immediate reuse of a 24-bit QP number (commit f4ec9e95). However, for other resources which use the bitmap allocator and involve mapping ICM memory -- MPTs, CQs, SRQs -- round-robin is not desirable. What happens in these cases is the following: ICM memory is allocated and mapped in chunks of 256K. Since the resource allocation index goes up monotonically, the allocator will eventually require mapping a new chunk. Now, chunks are also unmapped when their reference count goes back to zero. Thus, if a single app is running and starts/exits frequently we will have the following situation: When the app starts, a new chunk must be allocated and mapped. When the app exits, the chunk reference count goes back to zero, and the chunk is unmapped and freed. Therefore, the app must pay the cost of allocation and mapping of ICM memory each time it runs (although the price is paid only when allocating the initial entry in the new chunk). For apps which allocate MPTs/SRQs/CQs and which operate as described above, this presented a performance problem. We therefore roll back the round-robin allocator modification for MPTs, CQs, SRQs. Reported-by:Matthew Finlay <matt@mellanox.com> Signed-off-by: