[alsa-devel] [PATCH] ALSA: hda: Request driver probe from an async task
Takashi Iwai
tiwai at suse.de
Tue Apr 24 16:10:28 CEST 2018
On Tue, 24 Apr 2018 16:03:53 +0200,
Paul Menzel wrote:
>
> Dear Takashi,
>
>
> On 04/24/18 14:15, Takashi Iwai wrote:
> > On Tue, 24 Apr 2018 13:59:58 +0200,
> > Paul Menzel wrote:
>
> >> On 04/23/18 14:33, Takashi Iwai wrote:
> >>> On Mon, 23 Apr 2018 14:30:36 +0200, Paul Menzel wrote:
> >>
> >>>> On 04/23/18 14:21, Takashi Iwai wrote:
> >>>>> On Mon, 23 Apr 2018 14:05:52 +0200, Paul Menzel wrote:
> >>>>>>
> >>>>>> From: Paul Menzel <pmenzel at molgen.mpg.de>
> >>>>>> Date: Sat, 24 Mar 2018 09:28:43 +0100
> >>>>>>
> >>>>>> On an ASRock E350M1, with Linux 4.17-rc1 according to `initcall_debug`
> >>>>>> calling `azx_driver_init` takes sometimes more than a few milliseconds,
> >>>>>> and up to 200 ms.
> >>>>>>
> >>>>>> ```
> >>>>>> [ 2.892598] calling azx_driver_init+0x0/0xfe4 [snd_hda_intel] @ 218
> >>>>>> [ 2.943002] initcall azx_driver_init+0x0/0xfe4 [snd_hda_intel]
> >>>>>> returned 0 after 49195 usecs
> >>>>>> ```
> >>>>>>
> >>>>>> Trying to execute the Linux kernel in less than 500 ms, this is quite a
> >>>>>> hold-up, and therefore request the probe from an async task.
> >>>>>>
> >>>>>> With this change, the test shows, that the function returns earlier.
> >>>>>>
> >>>>>> ```
> >>>>>> [ 3.254800] calling azx_driver_init+0x0/0xfe4 [snd_hda_intel] @ 227
> >>>>>> [ 3.254887] initcall azx_driver_init+0x0/0xfe4 [snd_hda_intel]
> >>>>>> returned 0 after 66 usecs
> >>>>>> ```
> >>>>>>
> >>>>>> The same behavior is visible on a Dell OptiPlex 7010. The longer times
> >>>>>> seem to happen, when the module *e1000e* is probed during the same time.
> >>>>>>
> >>>>>> Signed-off-by: Paul Menzel <pmenzel at molgen.mpg.de>
> >>>>>
> >>>>> What actually took so long? Could you analyze further instead of
> >>>>> blindly putting the flag?
> >>>>
> >>>> Well, I am not sure. Could you please give me hints, how to debug this
> >>>> further? Is there some debug flag?
> >>>
> >>> Usually perf would help, but even a simple printk() should suffice to
> >>> see what's going on there :)
> >>
> >> Please find the messages for a 23 ms run below, and the debug patch
> >> attached.
> >>
> >>> [ 2.996238] calling azx_driver_init+0x0/0xfe4 [snd_hda_intel] @ 214
> >>> [ 3.009838] calling rtl8169_pci_driver_init+0x0/0x1000 [r8169] @ 217
> >>> [ 3.009904] r8169 Gigabit Ethernet driver 2.3LK-NAPI loaded
> >>> [ 3.010721] random: get_random_bytes called from ipv6_regen_rndid+0x2c/0x100 with crng_init=1
> >>> [ 3.011283] r8169 0000:03:00.0 eth0: RTL8168e/8111e at 0x(ptrval), bc:5f:f4:c8:d3:98, XID 0c200000 IRQ 26
> >>> [ 3.011289] r8169 0000:03:00.0 eth0: jumbo features [frames: 9200 bytes, tx checksumming: ko]
> >>> [ 3.013876] initcall rtl8169_pci_driver_init+0x0/0x1000 [r8169] returned 0 after 3917 usecs
> >>> [ 3.031754] calling pcspkr_platform_driver_init+0x0/0x1000 [pcspkr] @ 221
> >>> [ 3.031904] input: PC Speaker as /devices/platform/pcspkr/input/input4
> >>> [ 3.032288] initcall pcspkr_platform_driver_init+0x0/0x1000 [pcspkr] returned 0 after 508 usecs
> >>> [ 3.034795] calling psmouse_init+0x0/0x7c [psmouse] @ 220
> >>> [ 3.034903] initcall psmouse_init+0x0/0x7c [psmouse] returned 0 after 87 usecs
> >>> [ 3.043051] random: get_random_u32 called from cache_random_seq_create+0xa3/0x1f0 with crng_init=1
> >>> [ 3.043154] random: get_random_u32 called from cache_alloc_refill+0x5bb/0x13d0 with crng_init=1
> >>> [ 3.043187] random: get_random_u32 called from cache_random_seq_create+0xa3/0x1f0 with crng_init=1
> >>> [ 3.043198] random: get_random_u32 called from cache_alloc_refill+0x5bb/0x13d0 with crng_init=1
> >>> [ 3.043229] random: get_random_u32 called from cache_random_seq_create+0xa3/0x1f0 with crng_init=1
> >>> [ 3.043265] random: get_random_u32 called from cache_alloc_refill+0x5bb/0x13d0 with crng_init=1
> >>> [ 3.043429] random: get_random_u32 called from cache_random_seq_create+0xa3/0x1f0 with crng_init=1
> >>> [ 3.043479] random: get_random_u32 called from cache_alloc_refill+0x5bb/0x13d0 with crng_init=1
> >>> [ 3.043749] random: get_random_bytes called from key_alloc+0x1fc/0x5e0 with crng_init=1
> >>> [ 3.043973] random: get_random_u32 called from cache_random_seq_create+0xa3/0x1f0 with crng_init=1
> >>> [ 3.045483] random: get_random_u32 called from arch_rnd.part.2+0x18/0x40 with crng_init=1
> >>> [ 3.045501] random: get_random_u32 called from load_elf_binary+0x76a/0x1d20 with crng_init=1
> >>> [ 3.045507] random: get_random_u32 called from arch_align_stack+0x45/0x70 with crng_init=1
> >>> [ 3.045528] random: get_random_u32 called from arch_rnd.part.2+0x18/0x40 with crng_init=1
> >>> [ 3.045558] random: get_random_u32 called from cache_alloc_refill+0x5bb/0x13d0 with crng_init=1
> >>> [ 3.045771] random: get_random_u32 called from cache_random_seq_create+0xa3/0x1f0 with crng_init=1
> >>> [ 3.046127] random: get_random_u32 called from cache_alloc_refill+0x5bb/0x13d0 with crng_init=1
> >>> [ 3.046197] calling pcsp_init+0x0/0x1000 [snd_pcsp] @ 221
> >>> [ 3.046206] Error: Driver 'pcspkr' is already registered, aborting...
> >>> [ 3.046337] initcall pcsp_init+0x0/0x1000 [snd_pcsp] returned -16 after 128 usecs
> >>> [ 3.046348] random: get_random_u32 called from arch_align_stack+0x45/0x70 with crng_init=1
> >>> [ 3.046363] random: get_random_bytes called from load_elf_binary+0xaf8/0x1d20 with crng_init=1
> >>> [ 3.046383] random: get_random_u32 called from randomize_page+0x42/0x57 with crng_init=1
> >>> [ 3.047312] random: get_random_u32 called from cache_alloc_refill+0x5bb/0x13d0 with crng_init=1
> >>> [ 3.048151] random: get_random_u32 called from cache_random_seq_create+0xa3/0x1f0 with crng_init=1
> >>> [ 3.048638] random: get_random_u32 called from cache_alloc_refill+0x5bb/0x13d0 with crng_init=1
> >>> [ 3.054325] random: get_random_u32 called from copy_process.part.33+0x186/0x2100 with crng_init=1
> >>> [ 3.054371] random: get_random_u32 called from cache_alloc_refill+0x5bb/0x13d0 with crng_init=1
> >>> [ 3.067344] usb usb3: New USB device found, idVendor=1d6b, idProduct=0001, bcdDevice= 4.17
> >>> [ 3.067350] usb usb3: New USB device strings: Mfr=3, Product=2, SerialNumber=1
> >>> [ 3.067353] usb usb3: Product: OHCI PCI host controller
> >>> [ 3.067356] usb usb3: Manufacturer: Linux 4.17.0-rc2+ ohci_hcd
> >>> [ 3.067359] usb usb3: SerialNumber: 0000:00:12.0
> >>> [ 3.067850] random: get_random_u32 called from cache_random_seq_create+0xa3/0x1f0 with crng_init=1
> >>> [ 3.067864] hub 3-0:1.0: USB hub found
> >>> [ 3.067960] hub 3-0:1.0: 5 ports detected
> >>> [ 3.068141] random: get_random_u32 called from cache_alloc_refill+0x5bb/0x13d0 with crng_init=1
> >>> [ 3.068618] 1
> >>> [ 3.068644] 2
> >>> [ 3.068953] 3
> >>> [ 3.068954] 4
> >>> [ 3.068955] 5
> >>> [ 3.068959] 6
> >>> [ 3.068960] 7
> >>> [ 3.068966] 8
> >>> [ 3.068967] 9
> >>> [ 3.069204] 1
> >>> [ 3.069217] 2
> >>> [ 3.069565] 3
> >>> [ 3.069566] 4
> >>> [ 3.069567] 5
> >>> [ 3.069568] 6
> >>> [ 3.069569] 7
> >>> [ 3.069581] 8
> >>> [ 3.069583] 9
> >>> [ 3.069774] random: get_random_u32 called from copy_process.part.33+0x186/0x2100 with crng_init=1
> >>> [ 3.069924] initcall azx_driver_init+0x0/0xfe4 [snd_hda_intel] returned 0 after 23153 usecs
> >>
> >> Unfortunately, it looks like the time stamps of the Linux kernel and
> >> the initcall_debug time do not match. From the Linux time stamps it
> >> should be 73 ms.
> >
> > Indeed. But even from this result, you can have a rough idea.
> > As you can see, the most of time was spent before "1" point, which is
> > the very beginning of azx_probe(). That is, the slowness is not in
> > HD-audio driver probe itself. Rather it's likely because of parallel
> > probing with other multiple devices.
>
> I agree. But that also makes it clear, that the probe can be done in
> async task, doesn’t it?
Yes, but it's no fix, either. The probe callback itself doesn't take
any long time, but the problem is the stage before that. By declaring
the async probe, you can hide it, but it doesn't mean that the whole
issue is solved by that.
thanks,
Takashi
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