[PATCH v4 0/5] Add support for the ARMv8.2 Statistical Profiling Extension
Kim Phillips
kim.phillips at arm.com
Tue Jun 27 14:07:58 PDT 2017
On Thu, 22 Jun 2017 19:36:20 +0100
Will Deacon <will.deacon at arm.com> wrote:
> On Thu, Jun 22, 2017 at 10:56:40AM -0500, Kim Phillips wrote:
> > On Wed, 21 Jun 2017 16:31:09 +0100
> > Will Deacon <will.deacon at arm.com> wrote:
> >
> > > On Thu, Jun 15, 2017 at 10:57:35AM -0500, Kim Phillips wrote:
> > > > On Mon, 12 Jun 2017 11:20:48 -0500
> > > > Kim Phillips <kim.phillips at arm.com> wrote:
> > > >
> > > > > On Mon, 12 Jun 2017 12:08:23 +0100
> > > > > Mark Rutland <mark.rutland at arm.com> wrote:
> > > > >
> > > > > > On Mon, Jun 05, 2017 at 04:22:52PM +0100, Will Deacon wrote:
> > > > > > > This is the sixth posting of the patches previously posted here:
> > > > ...
> > > > > > Kim, do you have any version of the userspace side that we could look
> > > > > > at?
> > > > > >
> > > > > > For review, it would be really helpful to have something that can poke
> > > > > > the PMU, even if it's incomplete or lacking polish.
> > > > >
> > > > > Here's the latest push, based on a a couple of prior versions of this
> > > > > driver:
> > > > >
> > > > > http://linux-arm.org/git?p=linux-kp.git;a=shortlog;h=refs/heads/armspev0.1
> > > > >
> > > > > I don't seem to be able to get any SPE data output after rebasing on
> > > > > this version of the driver. Still don't know why at the moment...
> > > >
> > > > Bisected to commit e38ba76deef "perf tools: force uncore events to
> > > > system wide monitoring". So, using record with specifying a -C
> > > > <cpu> explicitly now produces SPE data, but only a couple of valid
> > > > records at the beginning of each buffer; the rest is filled with
> > > > PADding (0's).
> > > >
> > > > I see Mark's latest comments have found a possible issue in the perf
> > > > aux buffer handling code in the driver, and that the driver does some
> > > > memset of padding (0's) itself; could that be responsible for the above
> > > > behaviour?
> > >
> > > Possibly. Do you know how big you're mapping the aux buffer
> >
> > 4MiB.
> >
> > > and what (if any) value you're passing as aux_watermark?
> >
> > None passed, but it looks like 4KiB was used since the AUXTRACE size
> > was 4MiB - 4KiB.
> >
> > I'm not seeing the issue with a simple bts-based version I'm
> > working on...yet. We can revisit if I'm able to reproduce again; the
> > problem could have been on the userspace side.
I'm close to finishing the bts version of userspace, and have been
testing a bit more thoroughly, so now I consistently see the excessive
PADding when recording a CPU that's idle. I.e., when I taskset the perf
record to the same CPU I specify to record's -C (taskset -c n perf
record -C n), I get max. twenty-odd number of PAD bytes at the end of
the AUX buffers in the perf.data file. If, OTOH, I taskset -c n perf
record -C m, where m != n, I get a couple of valid event records in the
buffer, and the rest of the buffer is filled with PADding.
It wouldn't be a problem except that it's wastes too much space
sometimes. Here is a good output buffer sample from a --mmap-pages=,12
run, with only 4 PADs tacked onto the end:
0xd190 [0x30]: PERF_RECORD_AUXTRACE size: 0x48 offset: 0 ref: 0xe914f7e3ce idx: 0 tid: -1 cpu: 2
.
. ... ARM SPE data: size 72 bytes
. 00000000: 4a 01 B COND
. 00000002: b1 00 00 00 00 00 00 00 c0 TGT 0 el2 ns=1
. 0000000b: 42 42 RETIRED NOT-TAKEN
. 0000000d: b0 f4 4e 10 08 00 00 ff ff PC ff000008104ef4 el3 ns=1
. 00000016: 98 00 00 LAT 0 TOT
. 00000019: 71 a5 39 e1 14 e9 00 00 00 TS 1001077684645
. 00000022: 4a 02 B IND
. 00000024: b1 54 51 11 08 00 00 ff ff TGT ff000008115154 el3 ns=1
. 0000002d: 42 02 RETIRED
. 0000002f: b0 68 36 11 08 00 00 ff ff PC ff000008113668 el3 ns=1
. 00000038: 98 00 00 LAT 0 TOT
. 0000003b: 71 a5 39 e1 14 e9 00 00 00 TS 1001077684645
. 00000044: 00 PAD
. 00000045: 00 PAD
. 00000046: 00 PAD
. 00000047: 00 PAD
whereas this one - from later on in the same run - is over 99% PADs:
0xd250 [0x30]: PERF_RECORD_AUXTRACE size: 0x5fc0 offset: 0xfffff4ae0044 ref: 0xe91cead1dd idx: 0 tid: -1 cpu: 2
.
. ... ARM SPE data: size 24512 bytes
. 00000000: 4a 00 B
. 00000002: b1 cc 4e 10 08 00 00 ff ff TGT ff000008104ecc el3 ns=1
. 0000000b: 42 02 RETIRED
. 0000000d: b0 90 4e 10 08 00 00 ff ff PC ff000008104e90 el3 ns=1
. 00000016: 98 00 00 LAT 0 TOT
. 00000019: 71 a5 39 e1 14 e9 00 00 00 TS 1001077684645
. 00000022: 49 01 ST
. 00000024: b2 e0 2e f5 7d 00 80 ff ff VA ffff80007df52ee0
. 0000002d: b3 e0 2e f5 fd 00 00 00 80 PA fdf52ee0 ns=1
. 00000036: 9a 00 00 LAT 0 XLAT
. 00000039: 42 16 RETIRED L1D-ACCESS TLB-ACCESS
. 0000003b: b0 e8 41 39 08 00 00 ff ff PC ff0000083941e8 el3 ns=1
. 00000044: 98 00 00 LAT 0 TOT
. 00000047: 71 a5 39 e1 14 e9 00 00 00 TS 1001077684645
. 00000050: 4a 00 B
. 00000052: b1 58 f2 0f 08 00 00 ff ff TGT ff0000080ff258 el3 ns=1
. 0000005b: 42 02 RETIRED
. 0000005d: b0 90 de 0d 08 00 00 ff ff PC ff0000080dde90 el3 ns=1
. 00000066: 98 00 00 LAT 0 TOT
. 00000069: 71 8f 4e e1 14 e9 00 00 00 TS 1001077689999
. 00000072: 48 00 INSN-OTHER
. 00000074: 42 02 RETIRED
. 00000076: b0 f8 16 61 08 00 00 ff ff PC ff0000086116f8 el3 ns=1
. 0000007f: 98 00 00 LAT 0 TOT
. 00000082: 71 8f 4e e1 14 e9 00 00 00 TS 1001077689999
. 0000008b: 49 00 LD
. 0000008d: b2 10 34 ba 7b 00 80 ff ff VA ffff80007bba3410
. 00000096: b3 10 34 ba fb 00 00 00 80 PA fbba3410 ns=1
. 0000009f: 9a 00 00 LAT 0 XLAT
. 000000a2: 42 16 RETIRED L1D-ACCESS TLB-ACCESS
. 000000a4: b0 8c be 7a 08 00 00 ff ff PC ff0000087abe8c el3 ns=1
. 000000ad: 98 00 00 LAT 0 TOT
. 000000b0: 71 8f 4e e1 14 e9 00 00 00 TS 1001077689999
. 000000b9: 00 PAD
...ALL PADs...ALL PADs...ALL PADs...ALL PADs...ALL PADs...ALL PADs...
. 00005fbf: 00 PAD
So maybe there's an offset counter that isn't being reset properly;
hopefully the parallel discussion with Mark will help find the problem.
FWIW, there is also this one I saw with mmap-pages set to 5
(pages), which gets rounded up to 8 pages: the driver started
memsetting places it shouldn't?:
$ sudo ./perf record -c 512 -C 0 -e arm_spe/branch_filter=0,ts_enable=1,pa_enable=1,event_filter=0,load_filter=0,jitter=1,store_filter=0,min_latency=0/ --mmap-pages=,5 dd if=/dev/urandom of=/dev/null count=10000
rounding mmap pages size to 32K (8 pages)
10000+0 records in
10000+0 records out
5120000 bytes (5.1 MB) copied, 1.3391 s, 3.8 MB/s
[ 1885.042803] Unable to handle kernel paging request at virtual address ffff00000adac000
[ 1885.042873] pgd = ffff00000ad48000
[ 1885.042899] [ffff00000adac000] *pgd=00000000fdffe003, *pud=00000000fdffd003, *pmd=00000000fdff8003, *pte=0000000000000000
[ 1885.043083] Internal error: Oops: 96000047 [#1] PREEMPT SMP
[ 1885.043131] Modules linked in:
[ 1885.043200] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G W 4.12.0-rc5-00039-gf1d4a187881e #34
[ 1885.043299] Hardware name: FVP_Base_AEMv8A-AEMv8A (DT)
[ 1885.043364] task: ffff000008c21a80 task.stack: ffff000008c10000
[ 1885.043436] PC is at __memset+0x1ac/0x1d0
[ 1885.043499] LR is at __arm_spe_pmu_next_off+0x6c/0xd8
[ 1885.043600] pc : [<ffff00000837dbac>] lr : [<ffff0000086771e4>] pstate: 204001c9
[ 1885.043600] sp : ffff80007df22d10
[ 1885.043733] x29: ffff80007df22d10 x28: ffff000008c21a80
[ 1885.043819] x27: ffff000008c37768 x26: ffff80007df30280
[ 1885.043910] x25: ffff80007a109800 x24: 0000001d507d1906
[ 1885.044012] x23: ffff80007a601018 x22: ffff80007a3ebb00
[ 1885.044102] x21: ffff80007df36ab0 x20: ffff80007a3ebb00
[ 1885.044196] x19: ffff80007df36ab0 x18: 0000000000000000
[ 1885.044253] x17: 0000000000000000 x16: 0000000000000000
[ 1885.044339] x15: 0000000000000000 x14: ffff000008c21a80
[ 1885.044456] x13: 000080007532d000 x12: 000000003445d91d
[ 1885.044557] x11: 0000000000000000 x10: 0000000000001000
[ 1885.044600] x9 : 0000000000000000 x8 : ffff00000adac000
[ 1885.044729] x7 : 0000000000000000 x6 : 00000000000003ff
[ 1885.044800] x5 : 0000000000000400 x4 : 0000000000000000
[ 1885.044911] x3 : 0000000000000008 x2 : 0000000000003bff
[ 1885.045000] x1 : 0000000000000000 x0 : ffff00000ada8000
[ 1885.045100] Process swapper/0 (pid: 0, stack limit = 0xffff000008c10000)
[ 1885.045179] Stack: (0xffff80007df22d10 to 0xffff000008c14000)
[ 1885.045239] Call trace:
[ 1885.045300] Exception stack(0xffff80007df22b40 to 0xffff80007df22c70)
[ 1885.045400] 2b40: ffff80007df36ab0 0001000000000000 ffff80007df22d10 ffff00000837dbac
[ 1885.045505] 2b60: 0000000000000000 0000000000000000 ffff80007bb4b520 ffff00000837eac0
[ 1885.045605] 2b80: ffff80007df22d10 ffff0000080d6b58 0000000100060b21 ffff80007bb4afa8
[ 1885.045712] 2ba0: ffff80007bb4af20 ffff80007bb4af00 0000000000000000 ffff000008c19f04
[ 1885.045815] 2bc0: ffff000008bff000 ffff000008c17000 ffff80007bb53f00 000000000002fe89
[ 1885.045916] 2be0: ffff00000ada8000 0000000000000000 0000000000003bff 0000000000000008
[ 1885.046013] 2c00: 0000000000000000 0000000000000400 00000000000003ff 0000000000000000
[ 1885.046126] 2c20: ffff00000adac000 0000000000000000 0000000000001000 0000000000000000
[ 1885.046224] 2c40: 000000003445d91d 000080007532d000 ffff000008c21a80 0000000000000000
[ 1885.046326] 2c60: 0000000000000000 0000000000000000
[ 1885.046408] [<ffff00000837dbac>] __memset+0x1ac/0x1d0
[ 1885.046499] [<ffff00000867729c>] arm_spe_perf_aux_output_begin+0x4c/0x1b8
[ 1885.046599] [<ffff000008678424>] arm_spe_pmu_start+0x34/0xf0
[ 1885.046695] [<ffff000008678548>] arm_spe_pmu_add+0x68/0x98
[ 1885.046733] [<ffff00000814da54>] event_sched_in.isra.61+0xcc/0x218
[ 1885.046879] [<ffff00000814dc08>] group_sched_in+0x68/0x1a0
[ 1885.046981] [<ffff00000814dfd0>] ctx_sched_in+0x290/0x468
[ 1885.047080] [<ffff00000814e23c>] perf_event_sched_in+0x94/0xa8
[ 1885.047179] [<ffff00000814e2b4>] ctx_resched+0x64/0xb0
[ 1885.047268] [<ffff00000814e500>] __perf_event_enable+0x200/0x238
[ 1885.047366] [<ffff000008147118>] event_function+0x90/0xf0
[ 1885.047452] [<ffff0000081499e8>] remote_function+0x60/0x70
[ 1885.047514] [<ffff0000081194fc>] flush_smp_call_function_queue+0x9c/0x168
[ 1885.047637] [<ffff00000811a2a0>] generic_smp_call_function_single_interrupt+0x10/0x18
[ 1885.047733] [<ffff00000808e928>] handle_IPI+0xc0/0x1d8
[ 1885.047799] [<ffff000008081700>] gic_handle_irq+0x80/0x178
[ 1885.047799] Exception stack(0xffff000008c13d80 to 0xffff000008c13eb0)
[ 1885.047984] 3d80: 0000000000000000 ffff000008c21a80 00000000000003e8 ffff000008651430
[ 1885.048087] 3da0: 000000001999999a 0000000000000020 0000002bedec501b 0000000000000000
[ 1885.048190] 3dc0: 000001b2b5103510 ffff000008081800 0000000000001000 0000000000000000
[ 1885.048300] 3de0: 000000003445d91d 000080007532d000 ffff000008c21a80 0000000000000000
[ 1885.048400] 3e00: 0000000000000000 0000000000000000 0000000000000000 000001b6e54dc796
[ 1885.048505] 3e20: 0000000000000002 ffff80007a983c00 0000000000000002 ffff000008cdc130
[ 1885.048600] 3e40: 000001b6e5424132 ffff000008c21a80 0000000000000000 00000000fef7c684
[ 1885.048716] 3e60: 0000000080b10018 ffff000008c13eb0 ffff00000861014c ffff000008c13eb0
[ 1885.048817] 3e80: ffff00000861018c 0000000040c00149 00000000fef7c684 0000000000000002
[ 1885.048900] 3ea0: ffffffffffffffff ffff00000861014c
[ 1885.048900] [<ffff0000080827f4>] el1_irq+0xb4/0x128
[ 1885.049009] [<ffff00000861018c>] cpuidle_enter_state+0x154/0x200
[ 1885.049126] [<ffff000008610270>] cpuidle_enter+0x18/0x20
[ 1885.049207] [<ffff0000080ddd08>] call_cpuidle+0x18/0x30
[ 1885.049332] [<ffff0000080ddf44>] do_idle+0x19c/0x1d8
[ 1885.049400] [<ffff0000080de114>] cpu_startup_entry+0x24/0x28
[ 1885.049453] [<ffff0000087a6b30>] rest_init+0x80/0x90
[ 1885.049500] [<ffff000008b10b3c>] start_kernel+0x374/0x388
[ 1885.049617] [<ffff000008b101e0>] __primary_switched+0x64/0x6c
[ 1885.049699] Code: 91010108 54ffff4a 8b040108 cb050042 (d50b7428)
[ 1885.049800] ---[ end trace 31b9a9f27da95f58 ]---
[ 1885.049900] Kernel panic - not syncing: Fatal exception in interrupt
[ 1885.050000] SMP: stopping secondary CPUs
[ 1885.050204] Kernel Offset: disabled
[ 1885.050240] Memory Limit: none
[ 1885.050327] ---[ end Kernel panic - not syncing: Fatal exception in interrupt
It's not easily reproduced.
> > Meanwhile, when using fvp-base.dtb, my model setup stops booting the
> > kernel after "smp: Bringing up secondary CPUs ...". If I however take
> > the second SPE node from fvp-base.dts and add it to my working device
> > tree, I get this during the driver probe:
> >
> > [ 1.042063] arm_spe_pmu spe-pmu at 0: probed for CPUs 0-7 [max_record_sz 64, align 1, features 0xf]
> > [ 1.043582] arm_spe_pmu spe-pmu at 1: probed for CPUs 0-7 [max_record_sz 64, align 1, features 0xf]
> > [ 1.043631] genirq: Flags mismatch irq 6. 00004404 (arm_spe_pmu) vs. 00004404 (arm_spe_pmu)
>
> Looks like you've screwed up your IRQ partitions, so you are effectively
> registering the same device twice, which then blows up due to lack of shared
> irqs.
>
> Either remove one of the devices, or use IRQ partitions to restrict them
> to unique sets of CPUs.
Right, but since I want to get parity with what you're running -
fvp_base.dtb - I tried to debug the hang after "smp: Bringing up
secondary CPUs ..." problem, and could only debug it to the PSCI driver
hitting one of these cases:
case PSCI_RET_INVALID_PARAMS:
case PSCI_RET_INVALID_ADDRESS:
Note: it's yet another place I have to manually instrument the error
path in a kernel driver in lieu of it being more naturally verbose by
itself; I *implore* you to reconsider adding proper user messaging to
arm_spe_pmu_event_init().
I can't tell which part of the fvp-base device tree is not liked by the
firmware; I tried different combinations of the PSCI node, different CPU
enumerations (cpu at 100 vs cpu at 1), removing idle-states properties...any
hints appreciated.
Thanks,
Kim
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