Re: [PATCH v2 00/11] perf/uprobe: Optimize uprobes

[Andrii Nakryiko]

On Fri, Jul 19, 2024 at 11:42 AM Andrii Nakryiko
<andrii.nakryiko@xxxxxxxxx> wrote:
>
> On Mon, Jul 15, 2024 at 11:10 AM Andrii Nakryiko
> <andrii.nakryiko@xxxxxxxxx> wrote:
> >
> > On Mon, Jul 15, 2024 at 10:10 AM Andrii Nakryiko
> > <andrii.nakryiko@xxxxxxxxx> wrote:
> > >
> > > On Mon, Jul 15, 2024 at 7:45 AM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> > > >
> > > > On Thu, Jul 11, 2024 at 09:57:44PM -0700, Andrii Nakryiko wrote:
> > > >
> > > > > But then I also ran it on Linux built from perf/uprobes branch (these
> > > > > patches), and after a few seconds I see that there is no more
> > > > > attachment/detachment happening. Eventually I got splats, which you
> > > > > can see in [1]. I used `sudo ./uprobe-stress -a10 -t5 -m5 -f3` command
> > > > > to run it inside my QEMU image.
> > > >
> > > > So them git voodoo incantations did work and I got it built. I'm running
> > > > that exact same line above (minus the sudo, because test box only has a
> > > > root account I think) on real hardware.
> > > >
> > > > I'm now ~100 periods in and wondering what 'eventually' means...
> > >
> > > So I was running in a qemu set up with 16 cores on top of bare metal's
> > > 80 core CPU (Intel(R) Xeon(R) Gold 6138 CPU @ 2.00GHz). I just tried
> > > it again, and I can reproduce it within first few periods:
> > >
> > > WORKING HARD!..
> > >
> > > PERIOD #1 STATS:
> > > FUNC CALLS               919632
> > > UPROBE HITS              706351
> > > URETPROBE HITS           641679
> > > ATTACHED LINKS              951
> > > ATTACHED UPROBES           2421
> > > ATTACHED URETPROBES        2343
> > > MMAP CALLS                33533
> > > FORKS CALLS                 241
> > >
> > > PERIOD #2 STATS:
> > > FUNC CALLS                11444
> > > UPROBE HITS               14320
> > > URETPROBE HITS             9896
> > > ATTACHED LINKS               26
> > > ATTACHED UPROBES             75
> > > ATTACHED URETPROBES          61
> > > MMAP CALLS                39093
> > > FORKS CALLS                  14
> > >
> > > PERIOD #3 STATS:
> > > FUNC CALLS                  230
> > > UPROBE HITS                 152
> > > URETPROBE HITS              145
> > > ATTACHED LINKS                2
> > > ATTACHED UPROBES              2
> > > ATTACHED URETPROBES           2
> > > MMAP CALLS                39121
> > > FORKS CALLS                   0
> > >
> > > PERIOD #4 STATS:
> > > FUNC CALLS                    0
> > > UPROBE HITS                   0
> > > URETPROBE HITS                0
> > > ATTACHED LINKS                0
> > > ATTACHED UPROBES              0
> > > ATTACHED URETPROBES           0
> > > MMAP CALLS                39010
> > > FORKS CALLS                   0
> > >
> > > You can see in the second period all the numbers drop and by period #4
> > > (which is about 20 seconds in) anything but mmap()ing stops. When I
> > > said "eventually" I meant about a minute tops, however long it takes
> > > to do soft lockup detection, 23 seconds this time.
> > >
> > > So it should be very fast.
> > >
> > > Note that I'm running with debug kernel configuration (see [0] for
> > > full kernel config), here are debug-related settings, in case that
> > > makes a difference:
> > >
> > > $ cat ~/linux-build/default/.config | rg -i debug | rg -v '^#'
> > > CONFIG_X86_DEBUGCTLMSR=y
> > > CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC=y
> > > CONFIG_BLK_DEBUG_FS=y
> > > CONFIG_PNP_DEBUG_MESSAGES=y
> > > CONFIG_AIC7XXX_DEBUG_MASK=0
> > > CONFIG_AIC79XX_DEBUG_MASK=0
> > > CONFIG_SCSI_MVSAS_DEBUG=y
> > > CONFIG_DM_DEBUG=y
> > > CONFIG_MLX4_DEBUG=y
> > > CONFIG_USB_SERIAL_DEBUG=m
> > > CONFIG_INFINIBAND_MTHCA_DEBUG=y
> > > CONFIG_INFINIBAND_IPOIB_DEBUG=y
> > > CONFIG_INFINIBAND_IPOIB_DEBUG_DATA=y
> > > CONFIG_CIFS_DEBUG=y
> > > CONFIG_DLM_DEBUG=y
> > > CONFIG_DEBUG_BUGVERBOSE=y
> > > CONFIG_DEBUG_KERNEL=y
> > > CONFIG_DEBUG_INFO=y
> > > CONFIG_DEBUG_INFO_DWARF4=y
> > > CONFIG_DEBUG_INFO_COMPRESSED_NONE=y
> > > CONFIG_DEBUG_INFO_BTF=y
> > > CONFIG_DEBUG_INFO_BTF_MODULES=y
> > > CONFIG_DEBUG_FS=y
> > > CONFIG_DEBUG_FS_ALLOW_ALL=y
> > > CONFIG_ARCH_HAS_DEBUG_WX=y
> > > CONFIG_HAVE_DEBUG_KMEMLEAK=y
> > > CONFIG_ARCH_HAS_DEBUG_VM_PGTABLE=y
> > > CONFIG_ARCH_HAS_DEBUG_VIRTUAL=y
> > > CONFIG_SCHED_DEBUG=y
> > > CONFIG_DEBUG_PREEMPT=y
> > > CONFIG_LOCK_DEBUGGING_SUPPORT=y
> > > CONFIG_DEBUG_RT_MUTEXES=y
> > > CONFIG_DEBUG_SPINLOCK=y
> > > CONFIG_DEBUG_MUTEXES=y
> > > CONFIG_DEBUG_WW_MUTEX_SLOWPATH=y
> > > CONFIG_DEBUG_RWSEMS=y
> > > CONFIG_DEBUG_LOCK_ALLOC=y
> > > CONFIG_DEBUG_LOCKDEP=y
> > > CONFIG_DEBUG_ATOMIC_SLEEP=y
> > > CONFIG_DEBUG_IRQFLAGS=y
> > > CONFIG_X86_DEBUG_FPU=y
> > > CONFIG_FAULT_INJECTION_DEBUG_FS=y
> > >
> > >   [0] https://gist.github.com/anakryiko/97a023a95b30fb0fe607ff743433e64b
> > >
> > > >
> > > > Also, this is a 2 socket, 10 core per socket, 2 threads per core
> > > > ivybridge thing, are those parameters sufficient?
> > >
> > > Should be, I guess? It might be VM vs bare metal differences, though.
> > > I'll try to run this on bare metal with more production-like kernel
> > > configuration to see if I can still trigger this. Will let you know
> > > the results when I get them.
> >
> > Ok, so I ran it on bare metal host with production config. I didn't
> > really bother to specify parameters (so just one thread for
> > everything, the default):
> >
> > # ./uprobe-stress
> > WORKING HARD!..
> >
> > PERIOD #1 STATS:
> > FUNC CALLS              2959843
> > UPROBE HITS             1001312
> > URETPROBE HITS                0
> > ATTACHED LINKS                6
> > ATTACHED UPROBES             28
> > ATTACHED URETPROBES           0
> > MMAP CALLS                 8143
> > FORKS CALLS                 301
> >
> > PERIOD #2 STATS:
> > FUNC CALLS                    0
> > UPROBE HITS              822826
> > URETPROBE HITS                0
> > ATTACHED LINKS                0
> > ATTACHED UPROBES              0
> > ATTACHED URETPROBES           0
> > MMAP CALLS                 8006
> > FORKS CALLS                 270
> >
> > PERIOD #3 STATS:
> > FUNC CALLS                    0
> > UPROBE HITS              889534
> > URETPROBE HITS                0
> > ATTACHED LINKS                0
> > ATTACHED UPROBES              0
> > ATTACHED URETPROBES           0
> > MMAP CALLS                 8004
> > FORKS CALLS                 288
> >
> > PERIOD #4 STATS:
> > FUNC CALLS                    0
> > UPROBE HITS              886506
> > URETPROBE HITS                0
> > ATTACHED LINKS                0
> > ATTACHED UPROBES              0
> > ATTACHED URETPROBES           0
> > MMAP CALLS                 8120
> > FORKS CALLS                 285
> >
> > PERIOD #5 STATS:
> > FUNC CALLS                    0
> > UPROBE HITS              804556
> > URETPROBE HITS                0
> > ATTACHED LINKS                0
> > ATTACHED UPROBES              0
> > ATTACHED URETPROBES           0
> > MMAP CALLS                 7131
> > FORKS CALLS                 263
> > ^C
> > EXITING...
> >
> > Message from syslogd@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx at Jul 15 11:06:33 ...
> >  kernel:[ 2194.334618] watchdog: BUG: soft lockup - CPU#71 stuck for
> > 48s! [uprobe-stress:69900]
> >
> > It was weird on the very first period (no uretprobes, small amount of
> > attachments). And sure enough (gmail will reformat below in the
> > garbage, so [0] has the splat with the original formatting).
> >
> >   [0] https://gist.github.com/anakryiko/3e3ddcccc5ea3ca70ce90b5491485fdc
> >
> > I also keep getting:
> >
> > Message from syslogd@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx at Jul 15 11:09:41 ...
> >  kernel:[ 2382.334088] watchdog: BUG: soft lockup - CPU#71 stuck for
> > 223s! [uprobe-stress:69900]
> >
> > so it's not just a temporary slowdown
> >
> >
> > [ 2166.893057] rcu: INFO: rcu_sched self-detected stall on CPU
> > [ 2166.904199] rcu:     71-....: (20999 ticks this GP)
> > idle=2c84/1/0x4000000000000000 softirq=30158/30158 fqs=8110
> > [ 2166.923810] rcu:              hardirqs   softirqs   csw/system
> > [ 2166.934939] rcu:      number:        0        183            0
> > [ 2166.946064] rcu:     cputime:       60          0        10438
> > ==> 10549(ms)
> > [ 2166.959969] rcu:     (t=21065 jiffies g=369217 q=207850 ncpus=80)
> > [ 2166.971619] CPU: 71 PID: 69900 Comm: uprobe-stress Tainted: G S
> >      E      6.10.0-rc7-00071-g9423ae8ef6ff #62
> > [ 2166.992275] Hardware name: Quanta Tioga Pass Single Side
> > 01-0032211004/Tioga Pass Single Side, BIOS F08_3A24 05/13/2020
> > [ 2167.013804] RIP: 0010:uprobe_notify_resume+0x622/0xe20
> > [ 2167.024064] Code: 8d 9d c0 00 00 00 48 89 df 4c 89 e6 e8 d7 f9 ff
> > ff 84 c0 0f 85 c6 06 00 00 48 89 5c 24 20 41 8b 6d 58 40 f6 c5 01 74
> > 23 f3 90 <eb> f2 83 7c 24 18 00 48 8b 44 24 10 0f 8e 71 01 00 00 bf 05
> > 00 00
> > [ 2167.061543] RSP: 0000:ffffc9004a49fe78 EFLAGS: 00000202
> > [ 2167.071973] RAX: 0000000000000000 RBX: ffff88a11d307fc0 RCX: ffff88a120752c40
> > [ 2167.086223] RDX: 00000000000042ec RSI: ffffc9004a49ff58 RDI: ffff88a11d307fc0
> > [ 2167.100472] RBP: 0000000000000003 R08: ffff88a12516e500 R09: ffff88a12516f208
> > [ 2167.114717] R10: 00000000004042ec R11: 000000000000000f R12: ffffc9004a49ff58
> > [ 2167.128967] R13: ffff88a11d307f00 R14: 00000000004042ec R15: ffff88a09042e000
> > [ 2167.143213] FS:  00007fd252000640(0000) GS:ffff88bfffbc0000(0000)
> > knlGS:0000000000000000
> > [ 2167.159368] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > [ 2167.170843] CR2: 00007fd244000b60 CR3: 000000209090b001 CR4: 00000000007706f0
> > [ 2167.185091] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > [ 2167.199340] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > [ 2167.213586] PKRU: 55555554
> > [ 2167.218994] Call Trace:
> > [ 2167.223883]  <IRQ>
> > [ 2167.227905]  ? rcu_dump_cpu_stacks+0x77/0xd0
> > [ 2167.236433]  ? print_cpu_stall+0x150/0x2a0
> > [ 2167.244615]  ? rcu_sched_clock_irq+0x319/0x490
> > [ 2167.253487]  ? update_process_times+0x71/0xa0
> > [ 2167.262191]  ? tick_nohz_handler+0xc0/0x100
> > [ 2167.270544]  ? tick_setup_sched_timer+0x170/0x170
> > [ 2167.279937]  ? __hrtimer_run_queues+0xe3/0x250
> > [ 2167.288815]  ? hrtimer_interrupt+0xf0/0x390
> > [ 2167.297168]  ? __sysvec_apic_timer_interrupt+0x47/0x110
> > [ 2167.307602]  ? sysvec_apic_timer_interrupt+0x68/0x80
> > [ 2167.317519]  </IRQ>
> > [ 2167.321710]  <TASK>
> > [ 2167.325905]  ? asm_sysvec_apic_timer_interrupt+0x16/0x20
> > [ 2167.336517]  ? uprobe_notify_resume+0x622/0xe20
> > [ 2167.345565]  ? uprobe_notify_resume+0x609/0xe20
> > [ 2167.354612]  ? __se_sys_futex+0xf3/0x180
> > [ 2167.362445]  ? arch_uprobe_exception_notify+0x29/0x40
> > [ 2167.372533]  ? notify_die+0x51/0xb0
> > [ 2167.379503]  irqentry_exit_to_user_mode+0x7f/0xd0
> > [ 2167.388896]  asm_exc_int3+0x35/0x40
> > [ 2167.395862] RIP: 0033:0x4042ec
> > [ 2167.401966] Code: fc 8b 45 fc 89 c7 e8 6f 07 00 00 83 c0 01 c9 c3
> > cc 48 89 e5 48 83 ec 10 89 7d fc 8b 45 fc 89 c7 e8 55 07 00 00 83 c0
> > 01 c9 c3 <cc> 48 89 e5 48 83 ec 10 89 7d fc 8b 45 fc 89 c7 e8 3b 07 00
> > 00 83
> > [ 2167.439439] RSP: 002b:00007fd251fff8a8 EFLAGS: 00000206
> > [ 2167.449874] RAX: 00000000004042ec RBX: 00007fd252000640 RCX: 000000000000001c
> > [ 2167.464122] RDX: 0000000000000033 RSI: 0000000000000064 RDI: 0000000000000033
> > [ 2167.478368] RBP: 00007fd251fff8d0 R08: 00007fd2523fa234 R09: 00007fd2523fa280
> > [ 2167.492617] R10: 0000000000000000 R11: 0000000000000246 R12: 00007fd252000640
> > [ 2167.506866] R13: 0000000000000016 R14: 00007fd252289930 R15: 0000000000000000
> > [ 2167.521117]  </TASK>
>
> Peter,
>
> Did you manage to reproduce this?

Ping.