netdev - Re: [PATCH net-next] test_bpf: indicate whether bpf prog got jited in test suite

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Date:	Thu, 30 Apr 2015 10:10:46 -0700
From:	Alexei Starovoitov <ast@...mgrid.com>
To:	Daniel Borkmann <daniel@...earbox.net>, davem@...emloft.net
CC:	netdev@...r.kernel.org, Nicolas Schichan <nschichan@...ebox.fr>
Subject: Re: [PATCH net-next] test_bpf: indicate whether bpf prog got jited
 in test suite

On 4/30/15 7:17 AM, Daniel Borkmann wrote:
> I think this is useful to verify whether a filter could be JITed or
> not in case of bpf_prog_enable >= 1, which otherwise the test suite
> doesn't tell besides taking a good peek at the performance numbers.
>
> Nicolas Schichan reported a bug in the ARM JIT compiler that rejected
> and waved the filter to the interpreter although it shouldn't have.
> Nevertheless, the test passes as expected, but such information is
> not visible.
>
> It's i.e. useful for the remaining classic JITs, but also for
> implementing remaining opcodes that are not yet present in eBPF JITs
> (e.g. ARM64 waves some of them to the interpreter). This minor patch
> allows to grep through dmesg to find those accordingly, but also
> provides a total summary, i.e.: [<X>/53 JIT'ed]
>
>    # echo 1 > /proc/sys/net/core/bpf_jit_enable
>    # insmod lib/test_bpf.ko
>    # dmesg | grep "jited:0"
>
> dmesg example on the ARM issue with JIT rejection:
>
> [...]
> [   67.925387] test_bpf: #2 ADD_SUB_MUL_K jited:1 24 PASS
> [   67.930889] test_bpf: #3 DIV_MOD_KX jited:0 794 PASS
> [   67.943940] test_bpf: #4 AND_OR_LSH_K jited:1 20 20 PASS
> [...]
>
> Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
> Cc: Nicolas Schichan <nschichan@...ebox.fr>
> Cc: Alexei Starovoitov <ast@...mgrid.com>

yeah. definitely useful addition.
Acked-by: Alexei Starovoitov <ast@...mgrid.com>

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