Commit 2efeaf1d authored by Michal Schmidt's avatar Michal Schmidt Committed by Jakub Kicinski
Browse files

qed: put cond_resched() in qed_dmae_operation_wait() 



It is OK to sleep in qed_dmae_operation_wait, because it is called only
in process context, while holding p_hwfn->dmae_info.mutex from one of
the qed_dmae_{host,grc}2{host,grc} functions.
The udelay(DMAE_MIN_WAIT_TIME=2) in the function is too short to replace
with usleep_range, but at least it's a suitable point for checking if we
should give up the CPU with cond_resched().

This lowers the latency caused by 'ethtool -d' from 10 ms to less than
2 ms on my test system with voluntary preemption.

Signed-off-by: default avatarMichal Schmidt <mschmidt@redhat.com>
Link: https://patch.msgid.link/20240930201307.330692-5-mschmidt@redhat.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent cf54ae6b

drivers/net/ethernet/qlogic/qed/qed_hw.c

+1 −0
Original line number Diff line number Diff line
@@ -596,6 +596,7 @@ static int qed_dmae_operation_wait(struct qed_hwfn *p_hwfn) 
	barrier();

	while (*p_hwfn->dmae_info.p_completion_word != DMAE_COMPLETION_VAL) {

		udelay(DMAE_MIN_WAIT_TIME);

		cond_resched();

		if (++wait_cnt > wait_cnt_limit) {

			DP_NOTICE(p_hwfn->cdev,

				  "Timed-out waiting for operation to complete. Completion word is 0x%08x expected 0x%08x.\n",