> -----邮件原件-----
> 发件人: Feifei Wang <feifei.wa...@arm.com>
> 发送时间: Tuesday, October 26, 2021 4:02 PM
> 收件人: Konstantin Ananyev <konstantin.anan...@intel.com>
> 抄送: dev@dpdk.org; nd <n...@arm.com>; Feifei Wang
> <feifei.wa...@arm.com>; Ruifeng Wang <ruifeng.w...@arm.com>
> 主题: [PATCH v5 4/5] lib/bpf: use wait event scheme for Rx/Tx iteration
>
> Instead of polling for cbi->use to be updated, use wait event scheme.
>
> Furthermore, delete 'const' for 'bpf_eth_cbi_wait'. This is because of a
> compilation error:
> -----------------------------------------------------------------------
> ../lib/eal/include/rte_common.h:36:13: error: read-only variable ‘value’
> used as ‘asm’ output
> 36 | #define asm __asm__
> | ^~~~~~~
>
> ../lib/eal/arm/include/rte_pause_64.h:66:3: note: in expansion of macro ‘asm’
> 66 | asm volatile("ldaxr %w[tmp], [%x[addr]]" \
> | ^~~
>
> ../lib/eal/arm/include/rte_pause_64.h:96:3: note: in expansion of macro
> ‘__LOAD_EXC_32’
> 96 | __LOAD_EXC_32((src), dst, memorder) \
> | ^~~~~~~~~~~~~
>
> ../lib/eal/arm/include/rte_pause_64.h:167:4: note: in expansion of macro
> ‘__LOAD_EXC’
> 167 | __LOAD_EXC((addr), value, memorder, size) \
> | ^~~~~~~~~~
>
> ../lib/bpf/bpf_pkt.c:125:3: note: in expansion of macro ‘rte_wait_event’
> 125 | rte_wait_event(&cbi->use, UINT32_MAX, ==, puse,
> -----------------------------------------------------------------------
>
> Signed-off-by: Feifei Wang <feifei.wa...@arm.com>
> Reviewed-by: Ruifeng Wang <ruifeng.w...@arm.com>
> ---
> lib/bpf/bpf_pkt.c | 11 ++++-------
> 1 file changed, 4 insertions(+), 7 deletions(-)
>
> diff --git a/lib/bpf/bpf_pkt.c b/lib/bpf/bpf_pkt.c index
> 6e8248f0d6..213d44a75a 100644
> --- a/lib/bpf/bpf_pkt.c
> +++ b/lib/bpf/bpf_pkt.c
> @@ -111,9 +111,9 @@ bpf_eth_cbi_unuse(struct bpf_eth_cbi *cbi)
> * Waits till datapath finished using given callback.
> */
> static void
> -bpf_eth_cbi_wait(const struct bpf_eth_cbi *cbi)
> +bpf_eth_cbi_wait(struct bpf_eth_cbi *cbi)
Hi, Konstantin
For this bpf patch, I delete 'const' through this is contrary to what we
discussed earlier. This is because if we keep 'constant' here and use
'rte_wait_event'
new macro, compiler will report error. And earlier the arm version cannot be
compiled
due to I forgot enable "wfe" config in the meson file, so this issue can not
happen before.
> {
> - uint32_t nuse, puse;
> + uint32_t puse;
>
> /* make sure all previous loads and stores are completed */
> rte_smp_mb();
> @@ -122,11 +122,8 @@ bpf_eth_cbi_wait(const struct bpf_eth_cbi *cbi)
>
> /* in use, busy wait till current RX/TX iteration is finished */
> if ((puse & BPF_ETH_CBI_INUSE) != 0) {
> - do {
> - rte_pause();
> - rte_compiler_barrier();
> - nuse = cbi->use;
> - } while (nuse == puse);
> + rte_wait_event(&cbi->use, UINT32_MAX, ==, puse,
> + __ATOMIC_RELAXED);
> }
> }
>
> --
> 2.25.1
