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Merge branch 'replace-bpf-memory-allocator-with-kmalloc_nolock-in-local-storage'
Amery Hung says:
====================
Replace BPF memory allocator with kmalloc_nolock() in local storage
This patchset tries to simplify bpf_local_storage.c by adopting
kmalloc_nolock(). This removes memory preallocation and reduces the
dependency of smap in bpf_selem_free() and bpf_local_storage_free().
The later will simplify a future refactor that replaces
local_storage->lock and b->lock [1].
RFC v1 tried to switch to kmalloc_nolock() unconditionally. However,
as there is substantial performance loss in socket local storage due to
1) defer_free() in kfree_nolock() and 2) no kfree_rcu() batching,
replacing kzalloc() is postponed until necessary improvements in mm
land.
Benchmark
./bench -p 1 local-storage-create --storage-type <socket,task> \
--batch-size <16,32,64>
The benchmark is a microbenchmark stress-testing how fast local storage
can be created. For task local storage, switching from BPF memory
allocator to kmalloc_nolock() yields a small amount of improvement. For
socket local storage, it remains roughly the same as nothing has changed.
Socket local storage
memory alloc batch creation speed creation speed diff
--------------- ---- ------------------ ----
kzalloc 16 144.149 ± 0.642k/s 3.10 kmallocs/create
(before) 32 144.379 ± 1.070k/s 3.08 kmallocs/create
64 144.491 ± 0.818k/s 3.13 kmallocs/create
kzalloc 16 146.180 ± 1.403k/s 3.10 kmallocs/create +1.4%
(not changed) 32 146.245 ± 1.272k/s 3.10 kmallocs/create +1.3%
64 145.012 ± 1.545k/s 3.10 kmallocs/create +0.4%
Task local storage
memory alloc batch creation speed creation speed diff
--------------- ---- ------------------ ----
BPF memory 16 24.668 ± 0.121k/s 2.54 kmallocs/create
allocator 32 22.899 ± 0.097k/s 2.67 kmallocs/create
(before) 64 22.559 ± 0.076k/s 2.56 kmallocs/create
kmalloc_nolock 16 25.796 ± 0.059k/s 2.52 kmallocs/create +4.6%
(after) 32 23.412 ± 0.069k/s 2.50 kmallocs/create +2.2%
64 23.717 ± 0.108k/s 2.60 kmallocs/create +5.1%
[1] https://lore.kernel.org/bpf/20251002225356.1505480-1-ameryhung@gmail.com/
v1 -> v2
- Only replace BPF memory allocator with kmalloc_nolock()
Link: https://lore.kernel.org/bpf/20251112175939.2365295-1-ameryhung@gmail.com/
====================
Link: https://patch.msgid.link/20251114201329.3275875-1-ameryhung@gmail.com
Signed-off-by: 
Alexei Starovoitov <ast@kernel.org>