cxgbe netmap: Avoid too frequent flush of CIDX by the NIC
Needs ReviewPublic
Actions

Authored by bwicht_verisign.com on Nov 6 2018, 1:49 PM.

Tags

None

Referenced Files

	Unknown Object (File)
	Dec 24 2023, 6:58 AM

	Unknown Object (File)
	Sep 1 2023, 4:01 AM

	Unknown Object (File)
	Jul 11 2023, 7:16 AM

	Unknown Object (File)
	Jul 1 2023, 5:00 PM

	Unknown Object (File)
	Jun 30 2023, 6:51 PM

	Unknown Object (File)
	May 17 2023, 8:50 PM

	Unknown Object (File)
	May 11 2023, 4:42 AM

	Unknown Object (File)
	May 9 2023, 1:43 PM

View All 10 Files

Subscribers

jch

Details

Reviewers

Summary

By default, CIDX (consumer index) is flushed by the NIC after every
update. That means a PCI transaction for each TX packet. By setting the
threshold to 32, the amount of PCI traffic is significantly reduced.

Submitted by: Marc De La Gueronniere <mdelagueronniere@verisign.com>
MFC after: 1 week
Sponsored by: Verisign, Inc.

Diff Detail

Lint

Lint Passed

Unit

No Test Coverage

Build Status

Buildable 20660
Build 20075: arc lint + arc unit

Event Timeline

bwicht_verisign.com created this revision.Nov 6 2018, 1:49 PM

Herald added a subscriber: ae. · View Herald TranscriptNov 6 2018, 1:49 PM

Harbormaster completed remote builds in B20660: Diff 50073.Nov 6 2018, 1:49 PM

lazy_tx_credit_flush in the driver is supposed to avoid the situation you described. Try setting it to 1 if it isn't already and see if that helps.

jch added a subscriber: jch.Nov 6 2018, 9:29 PM

In D17870#381915, @np wrote:

lazy_tx_credit_flush in the driver is supposed to avoid the situation you described. Try setting it to 1 if it isn't already and see if that helps.

In fact, we are using lazy_tx_credit_flush=1

Does this change have no impact when lazy_tx_credit_flush is used?

Revision Contents
Changeset List

Path

Size

sys/

dev/

cxgbe/

t4_netmap.c

1 line

Diff 50073

View Options

cxgbe netmap: Avoid too frequent flush of CIDX by the NICNeeds ReviewPublicActions