selftests/bpf: Fix conflicts with built-in functions in bench_local_storage_create

The fork function in gcc is considered a built in function due to
being used by libgcov when building with gnu extensions.

Rename fork to sched_process_fork to prevent this conflict.

See details:
https://github.com/gcc-mirror/gcc/commit/d1c38823924506d389ca58d02926ace21bdf82fa
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82457

Fixes the following error:

In file included from progs/bench_local_storage_create.c:6:
progs/bench_local_storage_create.c:43:14: error: conflicting types for
built-in function 'fork'; expected 'int(void)'
[-Werror=builtin-declaration-mismatch]
43 | int BPF_PROG(fork, struct task_struct *parent, struct
task_struct *child)
| ^~~~

Fixes: cbe9d93d58b1 ("selftests/bpf: Add bench for task storage creation")
Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230331075848.1642814-1-james.hilliard1@gmail.com

selftests/bpf: Add bench for task storage creation

This patch adds a task storage benchmark to the existing
local-storage-create benchmark.

For task storage,
./bench --storage-type task --batch-size 32:
bpf_ma: Summary: creates 30.456 ± 0.507k/s ( 30.456k/prod), 6.08 kmallocs/create
no bpf_ma: Summary: creates 31.962 ± 0.486k/s ( 31.962k/prod), 6.13 kmallocs/create

./bench --storage-type task --batch-size 64:
bpf_ma: Summary: creates 30.197 ± 1.476k/s ( 30.197k/prod), 6.08 kmallocs/create
no bpf_ma: Summary: creates 31.103 ± 0.297k/s ( 31.103k/prod), 6.13 kmallocs/create

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20230322215246.1675516-6-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

selftests/bpf: Add local-storage-create benchmark

This patch tests how many kmallocs is needed to create and free
a batch of UDP sockets and each socket has a 64bytes bpf storage.
It also measures how fast the UDP sockets can be created.

The result is from my qemu setup.

Before bpf_mem_cache_alloc/free:
./bench -p 1 local-storage-create
Setting up benchmark 'local-storage-create'...
Benchmark 'local-storage-create' started.
Iter 0 ( 73.193us): creates 213.552k/s (213.552k/prod), 3.09 kmallocs/create
Iter 1 (-20.724us): creates 211.908k/s (211.908k/prod), 3.09 kmallocs/create
Iter 2 ( 9.280us): creates 212.574k/s (212.574k/prod), 3.12 kmallocs/create
Iter 3 ( 11.039us): creates 213.209k/s (213.209k/prod), 3.12 kmallocs/create
Iter 4 (-11.411us): creates 213.351k/s (213.351k/prod), 3.12 kmallocs/create
Iter 5 ( -7.915us): creates 214.754k/s (214.754k/prod), 3.12 kmallocs/create
Iter 6 ( 11.317us): creates 210.942k/s (210.942k/prod), 3.12 kmallocs/create
Summary: creates 212.789 ± 1.310k/s (212.789k/prod), 3.12 kmallocs/create

After bpf_mem_cache_alloc/free:
./bench -p 1 local-storage-create
Setting up benchmark 'local-storage-create'...
Benchmark 'local-storage-create' started.
Iter 0 ( 68.265us): creates 243.984k/s (243.984k/prod), 1.04 kmallocs/create
Iter 1 ( 30.357us): creates 238.424k/s (238.424k/prod), 1.04 kmallocs/create
Iter 2 (-18.712us): creates 232.963k/s (232.963k/prod), 1.04 kmallocs/create
Iter 3 (-15.885us): creates 238.879k/s (238.879k/prod), 1.04 kmallocs/create
Iter 4 ( 5.590us): creates 237.490k/s (237.490k/prod), 1.04 kmallocs/create
Iter 5 ( 8.577us): creates 237.521k/s (237.521k/prod), 1.04 kmallocs/create
Iter 6 ( -6.263us): creates 238.508k/s (238.508k/prod), 1.04 kmallocs/create
Summary: creates 237.298 ± 2.198k/s (237.298k/prod), 1.04 kmallocs/create

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20230308065936.1550103-18-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>