Re: [PATCH v10 0/6] Re-introduce TX FIFO resize for larger EP bursting

From: Wesley Cheng
Date: Tue Jun 22 2021 - 18:01:22 EST

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In reply to: Ferry Toth: "Re: [PATCH v10 0/6] Re-introduce TX FIFO resize for larger EP bursting"
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On 6/22/2021 1:09 PM, Ferry Toth wrote:
> Hi
>
> Op 22-06-2021 om 20:38 schreef Wesley Cheng:
>>
>> On 6/19/2021 5:40 AM, Ferry Toth wrote:
>>> Hi
>>>
>>> Op 18-06-2021 om 00:25 schreef Wesley Cheng:
>>>> Hi,
>>>>
>>>> On 6/17/2021 2:55 PM, Ferry Toth wrote:
>>>>> Hi
>>>>>
>>>>> Op 17-06-2021 om 23:48 schreef Wesley Cheng:
>>>>>> Hi,
>>>>>>
>>>>>> On 6/17/2021 2:01 PM, Ferry Toth wrote:
>>>>>>> Hi
>>>>>>>
>>>>>>> Op 17-06-2021 om 11:58 schreef Wesley Cheng:
>>>>>>>> Changes in V10:
>>>>>>>>     - Fixed compilation errors in config where OF is not used
>>>>>>>> (error due to
>>>>>>>>       unknown symbol for of_add_property()). Add of_add_property()
>>>>>>>> stub.
>>>>>>>>     - Fixed compilation warning for incorrect argument being
>>>>>>>> passed to
>>>>>>>> dwc3_mdwidth
>>>>>>> This fixes the OOPS I had in V9. I do not see any change in
>>>>>>> performance
>>>>>>> on Merrifield though.
>>>>>> I see...thanks Ferry! With your testing, are you writing to the
>>>>>> device's
>>>>>> internal storage (ie UFS, eMMC, etc...), or did you use a ramdisk as
>>>>>> well?
>>>>> In this case I just tested the EEM path using iperf3.
>>>>>
>>>> Got it. I don't believe f_eem will use a high enough (if at all)
>>>> bMaxBurst value to change the TXFIFO size.
>>>>
>>>>>> If not with a ramdisk, we might want to give that a try to avoid the
>>>>>> storage path being the bottleneck. You can use "dd" to create an
>>>>>> empty
>>>>>> file, and then just use that as the LUN's backing file.
>>>>>>
>>>>>> echo ramdisk.img >
>>>>>> /sys/kernel/config/usb_gadget/g1/functions/mass_storage.0/lun.0/file
>>>>> Ah, why didn't I think of that. I have currently mass storage setup
>>>>> with
>>>>> eMMC but it seems that is indeed the bottleneck.
>>>>>
>>> I created a 64MB disk following the instructions here
>>> http://www.linux-usb.org/gadget/file_storage.html (that seems a little
>>> outdated, at least I can not start the first partition at sector 8, but
>>> minimum 2048), and added a test file on it.
>>>
>>> I then copy the file to /dev/shm prior to setting configfs (composite
>>> device gser/eem/mass_storage/uac2).
>>>
>>> journal shows:
>>>
>>> kernel: Mass Storage Function, version: 2009/09/11
>>> kernel: LUN: removable file: (no medium)
>>>
>>> I don't know what that means, because I see the test file on the
>>> ramdisk.
>>>
>>> Then I again used gnome disks to benchmark (read/write 10MB):
>>>
>>> With V10 on top v5.13.0-rc5:
>>>
>>> R/W speed = 35.6/35.8MB/s, access time 0.35ms
>>>
>>> With no patches on top v5.12.0:
>>>
>>> R/W speed = 35.7/36.1MB/s, access time 0.35ms
>> Hi Ferry,
>>
>>> I see no speed difference (and it's about the same as with the eMMC
>>> backed disk). But the patches are causing a new call trace
>>>
>> Would you happen to know what DWC3 controller revision the device is
>> using? The callstack print occurs, because it looks like it ran out of
>> internal memory, although there should be logic present for making sure
>> that at least there is enough room for 1 FIFO per endpoint. (possibly
>> the logic/math depends on the controller revision)

Hi Ferry,

>
> Do you know where I could find that in a file on the device?
>

Maybe you can just dump the DWC3 registers?
cat /sys/kernel/debug/usb/<controller name>/regdump

Was going to ask for the same to confirm the TXFIFO sizes from your
results below :).

> Otherwise, I'm hoping Andy will know?
>
>>
>> Also, is there a way to use just a mass storage only composition? Based
>> on the above observation, that probably means that the mass storage
>> interface wasn't resized at all, because the configuration took up a lot
>> of the internal FIFO space.
>
> Sure, it's configured through configfs. With only mass_storage I have:
>
> With V10 on top v5.13.0-rc5:
>
> R/W speed = 41,6/39,3MB/s, access time 0.33ms
>
> With no patches on top v5.12.0:
>
> R/W speed = 41,1/38,7MB/s, access time 0.38ms
>

Thanks Ferry! Could you collect the regdump, so I can confirm the two
things mentioned?

Thanks
Wesley Cheng

>> Thanks
>> Wesley Cheng
>>
>>> kernel: using random self ethernet address
>>> kernel: using random host ethernet address
>>> kernel: Mass Storage Function, version: 2009/09/11
>>> kernel: LUN: removable file: (no medium)
>>> kernel: usb0: HOST MAC aa:bb:cc:dd:ee:f2
>>> kernel: usb0: MAC aa:bb:cc:dd:ee:f1
>>> kernel: IPv6: ADDRCONF(NETDEV_CHANGE): usb0: link becomes ready
>>> kernel: dwc3 dwc3.0.auto: Fifosize(2154) > RAM size(2022) ep5in
>>> depth:115540359
>>> kernel: ------------[ cut here ]------------
>>> kernel: WARNING: CPU: 0 PID: 594 at drivers/usb/gadget/udc/core.c:278
>>> usb_ep_queue+0x75/0x80
>>> kernel: Modules linked in: usb_f_uac2 u_audio usb_f_mass_storage
>>> usb_f_eem u_ether usb_f_serial u_serial libcomposite rfcomm iptable_nat
>>> bnep snd_sof_nocodec spi_pxa2>
>>> kernel: CPU: 0 PID: 594 Comm: irq/14-dwc3 Not tainted
>>> 5.13.0-rc5-edison-acpi-standard #1
>>> kernel: Hardware name: Intel Corporation Merrifield/BODEGA BAY, BIOS 542
>>> 2015.01.21:18.19.48
>>> kernel: RIP: 0010:usb_ep_queue+0x75/0x80
>>> kernel: Code: 01 73 e4 48 8b 05 fb 63 06 01 48 85 c0 74 12 48 8b 78 08
>>> 44 89 e9 4c 89 e2 48 89 ee e8 74 05 00 00 44 89 e8 5d 41 5c 41 5d c3
>>> <0f> 0b 41 bd 94 ff ff ff >
>>> kernel: RSP: 0000:ffff91eec083fc98 EFLAGS: 00010082
>>> kernel: RAX: ffff8af20357d960 RBX: 0000000000000000 RCX:
>>> ffff8af202f06400
>>> kernel: RDX: 0000000000000a20 RSI: ffff8af208785780 RDI:
>>> ffff8af202e9ae00
>>> kernel: RBP: ffff8af202e9ae00 R08: 00000000000000c0 R09:
>>> ffff8af208785780
>>> kernel: R10: 00000000ffffe000 R11: 3fffffffffffffff R12:
>>> ffff8af208785780
>>> kernel: R13: 0000000000000000 R14: ffff8af202e9ae00 R15:
>>> ffff8af203e26cc0
>>> kernel: FS: 0000000000000000(0000) GS:ffff8af23e200000(0000)
>>> knlGS:0000000000000000
>>> kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>> kernel: CR2: 000055e2c21f2100 CR3: 0000000003b38000 CR4:
>>> 00000000001006f0
>>> kernel: Call Trace:
>>> kernel: u_audio_start_playback+0x107/0x1a0 [u_audio]
>>> kernel: composite_setup+0x224/0x1ba0 [libcomposite]
>>> kernel: ? dwc3_gadget_ep_queue+0xf6/0x1a0
>>> kernel: ? usb_ep_queue+0x2a/0x80
>>> kernel: ? configfs_composite_setup+0x6b/0x90 [libcomposite]
>>> kernel: configfs_composite_setup+0x6b/0x90 [libcomposite]
>>> kernel: dwc3_ep0_interrupt+0x469/0xa80
>>> kernel: dwc3_thread_interrupt+0x8ee/0xf40
>>> kernel: ? __wake_up_common_lock+0x85/0xb0
>>> kernel: ? disable_irq_nosync+0x10/0x10
>>> kernel: irq_thread_fn+0x1b/0x60
>>> kernel: irq_thread+0xd6/0x170
>>> kernel: ? irq_thread_check_affinity+0x70/0x70
>>> kernel: ? irq_forced_thread_fn+0x70/0x70
>>> kernel: kthread+0x116/0x130
>>> kernel: ? kthread_create_worker_on_cpu+0x60/0x60
>>> kernel: ret_from_fork+0x22/0x30
>>> kernel: ---[ end trace e5b9e28058c53584 ]---
>>> kernel: configfs-gadget gadget: u_audio_start_playback:451 Error!
>>> kernel: configfs-gadget gadget: u_audio_start_playback:451 Error!
>>> kernel: dwc3 dwc3.0.auto: request 000000003c32dcc5 was not queued to
>>> ep5in
>>> kernel: dwc3 dwc3.0.auto: request 00000000b2512aa9 was not queued to
>>> ep5in
>>> kernel: dwc3 dwc3.0.auto: Fifosize(2154) > RAM size(2022) ep5in
>>> depth:115540359
>>> kernel: configfs-gadget gadget: u_audio_start_playback:451 Error!
>>> kernel: configfs-gadget gadget: u_audio_start_playback:451 Error!
>>> kernel: dwc3 dwc3.0.auto: request 00000000b2512aa9 was not queued to
>>> ep5in
>>> kernel: dwc3 dwc3.0.auto: request 00000000036ac129 was not queued to
>>> ep5in
>>> kernel: dwc3 dwc3.0.auto: Fifosize(2154) > RAM size(2022) ep5in
>>> depth:115540359
>>> kernel: configfs-gadget gadget: u_audio_start_playback:451 Error!
>>> kernel: configfs-gadget gadget: u_audio_start_playback:451 Error!
>>> kernel: dwc3 dwc3.0.auto: request 00000000ad1b8c18 was not queued to
>>> ep5in
>>> kernel: dwc3 dwc3.0.auto: request 00000000fbc71244 was not queued to
>>> ep5in
>>> kernel: dwc3 dwc3.0.auto: Fifosize(2154) > RAM size(2022) ep5in
>>> depth:115540359
>>> kernel: configfs-gadget gadget: u_audio_start_playback:451 Error!
>>> kernel: configfs-gadget gadget: u_audio_start_playback:451 Error!
>>> kernel: dwc3 dwc3.0.auto: request 00000000fbc71244 was not queued to
>>> ep5in
>>> kernel: dwc3 dwc3.0.auto: request 00000000ad1b8c18 was not queued to
>>> ep5in
>>> kernel: dwc3 dwc3.0.auto: Fifosize(2154) > RAM size(2022) ep5in
>>> depth:115540359
>>> kernel: configfs-gadget gadget: u_audio_start_playback:451 Error!
>>> kernel: configfs-gadget gadget: u_audio_start_playback:451 Error!
>>> kernel: dwc3 dwc3.0.auto: request 000000003c32dcc5 was not queued to
>>> ep5in
>>> kernel: dwc3 dwc3.0.auto: request 00000000b2512aa9 was not queued to
>>> ep5in
>>>
>>> Removing uac2 from the config makes the call trace go away, but the R/W
>>> speed does not change.
>>>
>>>> :), not a problem...I've been working on getting the ideal set up for
>>>> the performance profiling for awhile, so anything I can do to make sure
>>>> we get some good results.
>>>>
>>>>> I'll try with a ramdisk and let you know.
>>>>>
>>>> Thanks again for the testing, Ferry.
>>>>
>>>> Thanks
>>>> Wesley Cheng
>>>>
>>>>>> Thanks
>>>>>> Wesley Cheng
>>>>>>
>>>>>>>> Changes in V9:
>>>>>>>>     - Fixed incorrect patch in series. Removed changes in DTSI, as
>>>>>>>> dwc3-qcom will
>>>>>>>>       add the property by default from the kernel.
>>>>>>>>
>>>>>>>> Changes in V8:
>>>>>>>>     - Rebased to usb-testing
>>>>>>>>     - Using devm_kzalloc for adding txfifo property in dwc3-qcom
>>>>>>>>     - Removed DWC3 QCOM ACPI property for enabling the txfifo
>>>>>>>> resize
>>>>>>>>
>>>>>>>> Changes in V7:
>>>>>>>>     - Added a new property tx-fifo-max-num for limiting how much
>>>>>>>> fifo
>>>>>>>> space the
>>>>>>>>       resizing logic can allocate for endpoints with large burst
>>>>>>>> values. This
>>>>>>>>       can differ across platforms, and tie in closely with overall
>>>>>>>> system latency.
>>>>>>>>     - Added recommended checks for DWC32.
>>>>>>>>     - Added changes to set the tx-fifo-resize property from
>>>>>>>> dwc3-qcom by
>>>>>>>> default
>>>>>>>>       instead of modifying the current DTSI files.
>>>>>>>>     - Added comments on all APIs/variables introduced.
>>>>>>>>     - Updated the DWC3 YAML to include a better description of the
>>>>>>>> tx-fifo-resize
>>>>>>>>       property and added an entry for tx-fifo-max-num.
>>>>>>>>
>>>>>>>> Changes in V6:
>>>>>>>>     - Rebased patches to usb-testing.
>>>>>>>>     - Renamed to PATCH series instead of RFC.
>>>>>>>>     - Checking for fs_descriptors instead of ss_descriptors for
>>>>>>>> determining the
>>>>>>>>       endpoint count for a particular configuration.
>>>>>>>>     - Re-ordered patch series to fix patch dependencies.
>>>>>>>>
>>>>>>>> Changes in V5:
>>>>>>>>     - Added check_config() logic, which is used to communicate the
>>>>>>>> number of EPs
>>>>>>>>       used in a particular configuration. Based on this, the DWC3
>>>>>>>> gadget driver
>>>>>>>>       has the ability to know the maximum number of eps utilized in
>>>>>>>> all
>>>>>>>> configs.
>>>>>>>>       This helps reduce unnecessary allocation to unused eps,
>>>>>>>> and will
>>>>>>>> catch fifo
>>>>>>>>       allocation issues at bind() time.
>>>>>>>>     - Fixed variable declaration to single line per variable, and
>>>>>>>> reverse xmas.
>>>>>>>>     - Created a helper for fifo clearing, which is used by ep0.c
>>>>>>>>
>>>>>>>> Changes in V4:
>>>>>>>>     - Removed struct dwc3* as an argument for
>>>>>>>> dwc3_gadget_resize_tx_fifos()
>>>>>>>>     - Removed WARN_ON(1) in case we run out of fifo space
>>>>>>>>     Changes in V3:
>>>>>>>>     - Removed "Reviewed-by" tags
>>>>>>>>     - Renamed series back to RFC
>>>>>>>>     - Modified logic to ensure that fifo_size is reset if we
>>>>>>>> pass the
>>>>>>>> minimum
>>>>>>>>       threshold. Tested with binding multiple FDs requesting 6
>>>>>>>> FIFOs.
>>>>>>>>
>>>>>>>> Changes in V2:
>>>>>>>>     - Modified TXFIFO resizing logic to ensure that each EP is
>>>>>>>> reserved a
>>>>>>>>       FIFO.
>>>>>>>>     - Removed dev_dbg() prints and fixed typos from patches
>>>>>>>>     - Added some more description on the dt-bindings commit message
>>>>>>>>
>>>>>>>> Currently, there is no functionality to allow for resizing the
>>>>>>>> TXFIFOs, and
>>>>>>>> relying on the HW default setting for the TXFIFO depth. In most
>>>>>>>> cases, the
>>>>>>>> HW default is probably sufficient, but for USB compositions that
>>>>>>>> contain
>>>>>>>> multiple functions that require EP bursting, the default settings
>>>>>>>> might not be enough. Also to note, the current SW will assign an
>>>>>>>> EP to a
>>>>>>>> function driver w/o checking to see if the TXFIFO size for that
>>>>>>>> particular
>>>>>>>> EP is large enough. (this is a problem if there are multiple HW
>>>>>>>> defined
>>>>>>>> values for the TXFIFO size)
>>>>>>>>
>>>>>>>> It is mentioned in the SNPS databook that a minimum of TX FIFO
>>>>>>>> depth = 3
>>>>>>>> is required for an EP that supports bursting. Otherwise, there
>>>>>>>> may be
>>>>>>>> frequent occurences of bursts ending. For high bandwidth
>>>>>>>> functions,
>>>>>>>> such as data tethering (protocols that support data aggregation),
>>>>>>>> mass
>>>>>>>> storage, and media transfer protocol (over FFS), the bMaxBurst
>>>>>>>> value
>>>>>>>> can be
>>>>>>>> large, and a bigger TXFIFO depth may prove to be beneficial in
>>>>>>>> terms
>>>>>>>> of USB
>>>>>>>> throughput. (which can be associated to system access latency,
>>>>>>>> etc...) It
>>>>>>>> allows for a more consistent burst of traffic, w/o any
>>>>>>>> interruptions, as
>>>>>>>> data is readily available in the FIFO.
>>>>>>>>
>>>>>>>> With testing done using the mass storage function driver, the
>>>>>>>> results
>>>>>>>> show
>>>>>>>> that with a larger TXFIFO depth, the bandwidth increased
>>>>>>>> significantly.
>>>>>>>>
>>>>>>>> Test Parameters:
>>>>>>>>     - Platform: Qualcomm SM8150
>>>>>>>>     - bMaxBurst = 6
>>>>>>>>     - USB req size = 256kB
>>>>>>>>     - Num of USB reqs = 16
>>>>>>>>     - USB Speed = Super-Speed
>>>>>>>>     - Function Driver: Mass Storage (w/ ramdisk)
>>>>>>>>     - Test Application: CrystalDiskMark
>>>>>>>>
>>>>>>>> Results:
>>>>>>>>
>>>>>>>> TXFIFO Depth = 3 max packets
>>>>>>>>
>>>>>>>> Test Case | Data Size | AVG tput (in MB/s)
>>>>>>>> -------------------------------------------
>>>>>>>> Sequential|1 GB x     |
>>>>>>>> Read      |9 loops    | 193.60
>>>>>>>>         |           | 195.86
>>>>>>>>              |           | 184.77
>>>>>>>>              |           | 193.60
>>>>>>>> -------------------------------------------
>>>>>>>>
>>>>>>>> TXFIFO Depth = 6 max packets
>>>>>>>>
>>>>>>>> Test Case | Data Size | AVG tput (in MB/s)
>>>>>>>> -------------------------------------------
>>>>>>>> Sequential|1 GB x     |
>>>>>>>> Read      |9 loops    | 287.35
>>>>>>>>         |           | 304.94
>>>>>>>>              |           | 289.64
>>>>>>>>              |           | 293.61
>>>>>>>> -------------------------------------------
>>>>>>>>
>>>>>>>> Wesley Cheng (6):
>>>>>>>>      usb: gadget: udc: core: Introduce check_config to verify USB
>>>>>>>>        configuration
>>>>>>>>      usb: gadget: configfs: Check USB configuration before adding
>>>>>>>>      usb: dwc3: Resize TX FIFOs to meet EP bursting requirements
>>>>>>>>      of: Add stub for of_add_property()
>>>>>>>>      usb: dwc3: dwc3-qcom: Enable tx-fifo-resize property by
>>>>>>>> default
>>>>>>>>      dt-bindings: usb: dwc3: Update dwc3 TX fifo properties
>>>>>>>>
>>>>>>>>     .../devicetree/bindings/usb/snps,dwc3.yaml         | 15 +-
>>>>>>>>     drivers/usb/dwc3/core.c                            |   9 +
>>>>>>>>     drivers/usb/dwc3/core.h                            | 15 ++
>>>>>>>>     drivers/usb/dwc3/dwc3-qcom.c                       |   9 +
>>>>>>>>     drivers/usb/dwc3/ep0.c                             |   2 +
>>>>>>>>     drivers/usb/dwc3/gadget.c                          | 212
>>>>>>>> +++++++++++++++++++++
>>>>>>>>     drivers/usb/gadget/configfs.c                      | 22 +++
>>>>>>>>     drivers/usb/gadget/udc/core.c                      | 25 +++
>>>>>>>>     include/linux/of.h                                 |   5 +
>>>>>>>>     include/linux/usb/gadget.h                         |   5 +
>>>>>>>>     10 files changed, 317 insertions(+), 2 deletions(-)
>>>>>>>>

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