Date:   Mon, 14 Sep 2020 18:53:36 -0700
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     Andrii Nakryiko <andriin@...com>, bpf <bpf@...r.kernel.org>,
        Network Development <netdev@...r.kernel.org>,
        Alexei Starovoitov <ast@...com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Kernel Team <kernel-team@...com>
Subject: Re: [PATCH bpf-next] selftests/bpf: merge most of test_btf into test_progs

On Mon, Sep 14, 2020 at 6:31 PM Alexei Starovoitov
<alexei.starovoitov@...il.com> wrote:
>
> On Wed, Sep 9, 2020 at 7:51 PM Andrii Nakryiko <andriin@...com> wrote:
> >
> > Move almost 200 tests from test_btf into test_progs framework to be exercised
> > regularly. Pretty-printing tests were left alone in test_btf because they are
> > very slow and were not even executed by default with test_btf. Also, they seem
> > to break when moved under test_progs and I didn't want to spend more time on
> > figuring out why they broke, given we don't want to execute them all the time
> > anyway.
> >
> > All the test_btf tests that were moved are modeled as proper sub-tests in
> > test_progs framework for ease of debugging and reporting.
> >
> > No functional or behavioral changes were intended, I tried to preserve
> > original behavior as close to the original as possible. `test_progs -v` will
> > activate "always_log" flag to emit BTF validation log.
> >
> > Signed-off-by: Andrii Nakryiko <andriin@...com>
> > ---
> >  tools/testing/selftests/bpf/prog_tests/btf.c | 6124 ++++++++++++++
> >  tools/testing/selftests/bpf/test_btf.c       | 7442 ++----------------
> >  2 files changed, 6796 insertions(+), 6770 deletions(-)
>
> Thanks for consolidating, but it's impossible to realistically review such diff.
> gmail web ui is super slow to even reply to such email.
> Could you split it into 'git mv' patch and other patches?
> The first move will break the selftests build, but I think that's ok.
> I'd rather live with such bisecting issue than no review.

Didn't see your email, when I just sent v2. I renamed test_btf into
test_btf_pprint and GIT properly detected a rename. It's now += 1000
lines and Gmail seem to be handling reply quite well.



> Also just noticed doing
> ./test_btf -p
> BTF pretty print array(#0)......OK
> BTF pretty print hash(#0)......[   83.134228] ------------[ cut here
> ]------------
> [   83.134907] WARNING: CPU: 3 PID: 2006 at kernel/bpf/hashtab.c:717
> htab_map_get_next_key+0x7fc/0xab0
> [   83.135962] Modules linked in: bpf_preload
> [   83.136403] CPU: 3 PID: 2006 Comm: test_btf Not tainted
> 5.9.0-rc1-00870-g2bab48c5bef0 #2930
> [   83.137328] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
> BIOS 1.11.0-2.el7 04/01/2014
> [   83.138337] RIP: 0010:htab_map_get_next_key+0x7fc/0xab0
> [   83.138947] Code: c0 45 31 e4 e9 0b ff ff ff 48 8b 7c 24 10 48 8d
> 70 30 89 ca e8 d5 8d 21 00 31 c0 48 83 c4 40 5b 5d 41 5c 41 5d 41 5e
> 41 5f c3 <0f> 0b e9 30 f8 ff ff 4c 8b 34 24 89 ca 41 89 dc 41 89 dd e9
> 70 fa
> [   83.140997] RSP: 0018:ffff8881df5b7d30 EFLAGS: 00010246
> [   83.141577] RAX: 0000000000000000 RBX: ffff8881eb537a98 RCX: 1ffff1103d6a6f58
> [   83.142345] RDX: dffffc0000000000 RSI: ffffffff84b180a0 RDI: ffff8881f05008c8
> [   83.143153] RBP: ffff8881e6cf8000 R08: 0000000000000000 R09: ffff8881e6cf8000
> [   83.143953] R10: ffff8881e793405a R11: ffffed103cf2680b R12: ffff8881f1d96898
> [   83.144739] R13: ffffffff83cdf8a0 R14: ffff8881eb537b78 R15: 000000000000005b
> [   83.145571] FS:  00007ff4f1d0a700(0000) GS:ffff8881f6f80000(0000)
> knlGS:0000000000000000
> [   83.146433] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   83.147076] CR2: 0000000000436ef1 CR3: 00000001dfc8e001 CR4: 00000000003706e0
> [   83.147842] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [   83.148679] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [   83.149474] Call Trace:
> [   83.149779]  ? memcpy+0x39/0x60
> [   83.150136]  map_seq_next+0x176/0x300
> [   83.150571]  ? map_seq_show+0x150/0x220
> [   83.151054]  seq_read+0x6ed/0xd70
> [   83.151423]  vfs_read+0x150/0x4a0
> [   83.151830]  ksys_read+0xe9/0x1b0
> [   83.152196]  ? vfs_write+0x620/0x620
> [   83.152644]  ? trace_hardirqs_on+0x20/0x170
> [   83.153133]  do_syscall_64+0x2d/0x40
> [   83.153542]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> [   83.154110] RIP: 0033:0x7ff4f0dd7bf0
> [   83.154498] Code: 0b 31 c0 48 83 c4 08 e9 ae fe ff ff 48 8d 3d 7f
> ed 08 00 e8 02 d4 01 00 66 90 83 3d 59 5b 2c 00 00 75 10 b8 00 00 00
> 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 ae 96 01 00 48 89
> 04 24
> [   83.156514] RSP: 002b:00007fffb93aeee8 EFLAGS: 00000246 ORIG_RAX:
> 0000000000000000
> [   83.157340] RAX: ffffffffffffffda RBX: 0000000000543040 RCX: 00007ff4f0dd7bf0
> [   83.158155] RDX: 0000000000001000 RSI: 0000000000543520 RDI: 0000000000000005
> [   83.158981] RBP: 0000000000543040 R08: 0000000000000003 R09: 0000000000001011
> [   83.159757] R10: 0000000000000000 R11: 0000000000000246 R12: 00007fffb93aefd8
> [   83.160538] R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000004
> [   83.161323] irq event stamp: 3514803
> [   83.161762] hardirqs last  enabled at (3514813):
> [<ffffffff81275931>] console_unlock+0x611/0x9d0
> [   83.162818] hardirqs last disabled at (3514822):
> [<ffffffff81275400>] console_unlock+0xe0/0x9d0
> [   83.163900] softirqs last  enabled at (3308060):
> [<ffffffff83a005a3>] __do_softirq+0x5a3/0x883
> [   83.164851] softirqs last disabled at (3308055):
> [<ffffffff83800ebf>] asm_call_on_stack+0xf/0x20
> [   83.165883] ---[ end trace 518a74dd5d67d50c ]---
> OK
> BTF pretty print lru hash(#0)......[   86.149427] perf: interrupt took
> too long (2577 > 2500), lowering kernel.perf_event_max_sample_rate to
> 77000
> OK
> BTF pretty print percpu array(#0)......[   89.952685] perf: interrupt
> took too long (3249 > 3221), lowering
> kernel.perf_event_max_sample_rate to 61000
> OK
> BTF pretty print percpu hash(#0)......OK
> BTF pretty print lru percpu hash(#0)......[  100.798017] perf:
> interrupt took too long (4160 > 4061), lowering
> kernel.perf_event_max_sample_rate to 48000
> OK
> BTF pretty print array(#1)......OK
> BTF pretty print array(#2)......OK
> BTF pretty print array(#3)......OK
> PASS:9 SKIP:0 FAIL:0
>
> They are slow, but they pass and clearly useful, since they caught above bug.

So are you suggesting to move them into test_progs as well? They do
pass for me when run standalone, but when I initially converted them
into test_progs they started failing and the perspective of figuring
out why wasn't very exciting. But besides that, having guaranteed very
slow tests running all the time is really demotivating. I'm already
quite often tempted to skip bpf_verif_scale due to how long they run,
having another set of even slower tests is just depressing. Unless we
introduce a default fast test subset vs opt-in slow full test suite,
it's just detrimental to a development process, IMO:

$ time sudo ./test_btf_pprint
BTF pretty print array(#0)......OK
BTF pretty print hash(#0)......OK
BTF pretty print lru hash(#0)......OK
BTF pretty print percpu array(#0)......OK
BTF pretty print percpu hash(#0)......OK
BTF pretty print lru percpu hash(#0)......OK
BTF pretty print array(#1)......OK
BTF pretty print array(#2)......OK
BTF pretty print array(#3)......OK
PASS:9 SKIP:0 FAIL:0
sudo ./test_btf_pprint  26.21s user 47.69s system 99% cpu 1:13.92 total

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