On 2018-05-22 14:15, Niklas Cassel wrote:
On Mon, May 21, 2018 at 04:11:38PM -0700, Rajkumar Manoharan wrote:
On 2018-05-21 13:43, Niklas Cassel wrote:
> The following problem was observed when running iperf:
[...]
Sorry for the late response. ath10k_mac_tx_push_pending is already
called
at the end of NAPI handler. Isn't that enough to process pending
frames?
This is true for e.g. ATH10K_BUS_PCI and ATH10K_BUS_SNOC,
but not for e.g. ATH10K_BUS_SDIO and ATH10K_BUS_USB.
While there is some SDIO code merged in Kalle's tree already,
this problem was found when merging
https://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git/?h=ath10k-pending-sdio-usb
with Kalle's ath-next branch.
Earlier we observed performance issues in calling push_pending from
each
tx completion. IMHO this change may introduce the same problem again.
I prefer functional TX over performance issues,
but I agree that it is unfortunate that SDIO doesn't use
ath10k_htt_txrx_compl_task().
Erik, is there a reason for this?
Thanks for details. Now I see your problem. In case of low latency
devices (PCI/SNOC/AHB),
all CE rings interrupts are serviced first and later consolidated data
processing done
from ath10k_htt_txrx_compl_task and then ath10k_mac_tx_push_pending is
called from NAPI Poll.
In case of high latency devices (USB/SDIO), each endpoints are serviced
and all tx/rx jobs
are completed from the same context. Hence no need of consolidated
processing.
Perhaps it would be possible to call ath10k_mac_tx_push_pending()
from the equivalent to ath10k_htt_txrx_compl_task(),
but from SDIO's point of view.
Another solution might be to change so that we only call
ath10k_mac_tx_push_pending() from ath10k_txrx_tx_unref()
if (htt->num_pending_tx == 0). That should decrease the number
of calls to ath10k_mac_tx_push_pending(), while still avoiding
a "TX deadlock" scenario for SDIO.
This issue is specific to HL devices. But your change is common which
will impact LL devices.
I would prefer to call ath10k_mac_tx_push_pending after processing all
received mbox/urb messages.
Export ath10k_mac_tx_push_pending API and call it from USB/SDIO irq
handler. Any thoughts?
-Rajkumar
