snd_pcm_writei() takes to much time to write data

[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.

[perexg]

If you write 8000 frames and rate is 8000Hz then it's exactly one second. If you want to write frames to the remaining space (buffer), then use snd_pcm_avail()/snd_pcm_avail_update() to identify the available frames or set the I/O mode to non-block snd_pcm_nonblock(). Otherwise the driver wait's until all frames are consumed (can be put to the buffer).