Re: [PATCH v10 0/6] Re-introduce TX FIFO resize for larger EP bursting
From: Ferry Toth
Date: Sat Jun 19 2021 - 08:40:56 EST
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outdated, at least I can not start the first partition at sector 8, but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
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
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(-)