5af666a94e
Currently timeout and buffer size are hard-coded in the fx2lafw driver which is non-optimal if we want to get good results at both high and low sample rates. The timeout is hard-coded to 40ms, which doesn't work well when sampling at a low sample rate. E.g. at 20kHz filling all available buffer space alone takes 6 seconds. So naturally we'll see a lot of transfers timeout in this case. The buffer size is hard-coded to 4096 bytes, which does not work well with high sample rates. E.g. at 24MHz these 4096 bytes are enough space for 0.17ms of data. The total buffer size is enough for about 5ms of data. Sooner or later the application won't be able to resubmit a transfer within this time span and the device will abort data acquisition. Usually this happens within the first few seconds of sampling. This patch adds a few new helper functions which calculate the buffer size and timeout based on the current sample rate. The buffer size is chosen to be large enough to hold about 10ms of data and it also must be a multiple of 512 bytes since the firmware will send us the data in 512 byte chunks. The timeout is set to the time it would take to fill the whole available buffer space plus a 25% headroom to accommodate for jitter. This is more than enough, but there is no need to make the timeout a tight deadline, since it is only meant as a last resort in case the device stops submitting data. And in this case data acquisition will be aborted anyway. The patch also limits the the number of transfers so that the total buffer space is not much more of 500ms. This will ensure that we do not have to wait too long when aborting data acquisition. This patch also significantly reduces the number of context switches when sampling at a higher sample rate. On my system for example the CPU load of sigrok-cli when sampling at 24MHz goes down from ~25% to 3-4%. Signed-off-by: Lars-Peter Clausen <lars@metafoo.de> |
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| .. | ||
| alsa | ||
| asix-sigma | ||
| chronovu-la8 | ||
| common | ||
| demo | ||
| fx2lafw | ||
| hantek-dso | ||
| link-mso19 | ||
| mastech-va18b | ||
| openbench-logic-sniffer | ||
| zeroplus-logic-cube | ||
| Makefile.am | ||