snd_pcm_readi() takes to much time to write data

[GitHub issues - opened <github@xxxxxxxxxxxxxxxx>]

alsa-project/alsa-lib issue #428 was opened from nnamera:

I am using the ALSA open-source library to read and write audio data for my project. To write audio data, I am calling the snd_pcm_writei function. Initially, it works as expected, but after writing 2-3 frames, the function starts taking significantly more time (around 1 second) to complete.

Normally, snd_pcm_writei should execute within 1-3 ms, but this delay is affecting my application's overall performance, causing audio chopping issues.

Here are the details of my setup:

Frame size: ~8000 bytes (writing 8000 bytes per call)

Plug PCM: Route conversion PCM (sformat=S16_LE)
  Transformation table:
    0 <- 0
    1 <- 0
Its setup is:
  stream       : PLAYBACK
  access       : RW_INTERLEAVED
  format       : S16_LE
  subformat    : STD
  channels     : 1
  rate         : 8000
  exact rate   : 8000 (8000/1)
  msbits       : 16
  buffer_size  : 4000
  period_size  : 1000
  period_time  : 125000
  tstamp_mode  : NONE
  tstamp_type  : MONOTONIC
  period_step  : 1
  avail_min    : 1000
  period_event : 0
  start_threshold  : 4000
  stop_threshold   : 4000
  silence_threshold: 0
  silence_size : 0
  boundary     : 9007199254740992000
Slave: Soft volume PCM
Control: amba-playback
min_dB: -20
max_dB: 20
resolution: 256
Its setup is:
  stream       : PLAYBACK
  access       : MMAP_INTERLEAVED
  format       : S16_LE
  subformat    : STD
  channels     : 2
  rate         : 8000
  exact rate   : 8000 (8000/1)
  msbits       : 16
  buffer_size  : 4000
  period_size  : 1000
  period_time  : 125000
  tstamp_mode  : NONE
  tstamp_type  : MONOTONIC
  period_step  : 1
  avail_min    : 1000
  period_event : 0
  start_threshold  : 4000
  stop_threshold   : 4000
  silence_threshold: 0
  silence_size : 0
  boundary     : 9007199254740992000
Slave: Hardware PCM card 0 'es8389' device 0 subdevice 0
Its setup is:
  stream       : PLAYBACK
  access       : MMAP_INTERLEAV[   22.206911] ambarella-i2c e400a000.i2c: No ACK from address 0x6c, 0:0!
ED
  format    [   22.214533] os04c10: probe of 2-0001 failed with error -5
   : S16_LE
  subformat    : STD
  channels     : 2
  rate         : 8000
  exact rate   : 8000 (8000/1)
  msbits       : 16
  buffer_size  : 4000
  period_size  : 1000
  period_time  : 125000
  tstamp_mode  : NONE
  tstamp_type  : MONOTONIC
  period_step  : 1
  avail_min    : 1000
  period_event : 0
  start_threshold  : 4000
  stop_threshold   : 4000
  silence_threshold: 0
  silence_size : 0
  boundary     : 9007199254740992000
  appl_ptr     : 0
  hw_ptr       : 0

I would appreciate any guidance or suggestions on why this delay is happening and how I can resolve it. Let me know if you need any additional details or logs.

Issue URL     : https://github.com/alsa-project/alsa-lib/issues/428
Repository URL: https://github.com/alsa-project/alsa-lib