Is there a way to reduce esp-wifi memory usage if not using ble/bluetooth/esp-now, and only using wifi?

[yanshay]

I'm still on 0.23.1, title pretty much says it all.
I'm in desperate need for internal RAM, so looking for any way to reduce internal RAM usage which mostly goes now to esp-wifi/esp-mbedtls .

[bjoernQ]

Only on the original ESP32 and only if you activate esp-wifi's ble feature there are 64k reserved for BT.

It would be possible (but unimplemented) to reclaim some of the memory when not using BT-classic and all of it when not using BT anymore (e.g. using BT for provisioning). However, the reclaimed memory would only be available as heap, not for the stack

[yanshay]

I'm on esp32s3, it seems like esp-wifi takes around 51Kb or maybe more (heap, see below).

This is my heap memory map when there's just one TLS session.
(all my other allocs go to PSRAM)

Jul 31 18:37:24 External | ████░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ | Used: 14% (Used 311764 of 2097152, free: 1785388)
Jul 31 18:37:24 Internal | ████████████████████████████████░░░ | Used: 93% (Used 61176 of 65536, free: 4360)
Jul 31 18:37:24 Internal | ██████░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ | Used: 19% (Used 33544 of 169984, free: 136440)

This is when another TLS session is added, so it looks like TLS takes (72796-33544) + (65324-61176) = 43,400.
Sometimes it appears to take less...

Jul 31 18:38:43 External | █████░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ | Used: 16% (Used 355820 of 2097152, free: 1741332)
Jul 31 18:38:43 Internal | ██████████████████████████████████░ | Used: 99% (Used 65324 of 65536, free: 212)
Jul 31 18:38:43 Internal | ██████████████░░░░░░░░░░░░░░░░░░░░░ | Used: 42% (Used 72796 of 169984, free: 97188)

So it seems like esp-wifi takes around 51320 (before adding TLS).

So are you saying it could be possible to reclaim some of that if not using BT at all but not implemented currently?
I'm good with heap, need extra memory for TLS sessions.

[Dominaezzz]

Do you need a fix for 0.23.1 or are you willing to upgrade to pull in memory usage improvements?

I'm thinking one can convince both esp-wifi and/or esp-mbedtls (this might be easier) to use PSRAM instead of internal RAM.

[Dominaezzz]

BTW - when moving tasks to PSRAM does it slow down their execution meaningfully having to fetch the state from PSRAM and back?

It will be slower but I don't know by how much (I'd guess you won't notice). The XiP from PSRAM stuff would also help here, (unless you don't use both cores).

[yanshay]

I don't think I use the XiP from PSRAM, is that the feature that copies flash to PSRAM?

I don't use it currently.

But how is it related to two cores usage? When I did try it for the display DMA and it didn't seem to help I also didn't use two cores. Does it have an effect only when using two cores?

[Dominaezzz]

If one core is trying to access PSRAM whilst the other core is trying to access flash, the first one will have to wait.

[yanshay]

So if I didn't use the other core it's not relevant and should still have worked?

[Dominaezzz]

I'm taking about CPU workloads

In the case of DMA, it doesn't need to be two cores, one is enough

[bjoernQ]

Another thing: currently esp-wifi allocated more than needed from internal RAM - I wanted to revisit that but not sure when I will get to that. We definitely don't backport anything however