bpf: Inline helper in powerpc JIT #8654
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March 12, 2025 16:28
…U addrs With the introduction of commit 7bdbf74 ("bpf: add special internal-only MOV instruction to resolve per-CPU addrs"), a new BPF instruction BPF_MOV64_PERCPU_REG has been added to resolve absolute addresses of per-CPU data from their per-CPU offsets. This update requires enabling support for this instruction in the powerpc JIT compiler. As of commit 7a0268f ("[PATCH] powerpc/64: per cpu data optimisations"), the per-CPU data offset for the CPU is stored in the paca. To support this BPF instruction in the powerpc JIT, the following powerpc instructions are emitted: mr dst_reg, src_reg //Move src_reg to dst_reg, if src_reg != dst_reg ld tmp1_reg, 48(13) //Load per-CPU data offset from paca(r13) in tmp1_reg. add dst_reg, dst_reg, tmp1_reg //Add the per cpu offset to the dst. To evaluate the performance improvements introduced by this change, the benchmark described in [1] was employed. Before Change: glob-arr-inc : 41.580 ± 0.034M/s arr-inc : 39.592 ± 0.055M/s hash-inc : 25.873 ± 0.012M/s After Change: glob-arr-inc : 42.024 ± 0.049M/s arr-inc : 55.447 ± 0.031M/s hash-inc : 26.565 ± 0.014M/s [1] anakryiko/linux@8dec900975ef Signed-off-by: Saket Kumar Bhaskar <[email protected]>
Inline the calls to bpf_get_smp_processor_id() in the powerpc bpf jit. powerpc saves the Logical processor number (paca_index) in paca. Here is how the powerpc JITed assembly changes after this commit: Before: cpu = bpf_get_smp_processor_id(); addis 12, 2, -517 addi 12, 12, -29456 mtctr 12 bctrl mr 8, 3 After: cpu = bpf_get_smp_processor_id(); lhz 8, 8(13) To evaluate the performance improvements introduced by this change, the benchmark described in [1] was employed. +---------------+-------------------+-------------------+--------------+ | Name | Before | After | % change | |---------------+-------------------+-------------------+--------------| | glob-arr-inc | 41.580 ± 0.034M/s | 54.137 ± 0.019M/s | + 30.20% | | arr-inc | 39.592 ± 0.055M/s | 54.000 ± 0.026M/s | + 36.39% | | hash-inc | 25.873 ± 0.012M/s | 26.334 ± 0.058M/s | + 1.78% | +---------------+-------------------+-------------------+--------------+ [1] anakryiko/linux@8dec900975ef Signed-off-by: Saket Kumar Bhaskar <[email protected]>
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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=942781 expired. Closing PR. |
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Pull request for series with
subject: bpf: Inline helper in powerpc JIT
version: 1
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=942781