From: "Wu, Jingjing" <jingjing.wu@intel.com>
To: "Hanoch Haim (hhaim)" <hhaim@cisco.com>, "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] net/i40e: latency issue due fix interrupt throttling setting in PF
Date: Tue, 28 Nov 2017 12:50:01 +0000 [thread overview]
Message-ID: <9BB6961774997848B5B42BEC655768F810EC8AC3@SHSMSX103.ccr.corp.intel.com> (raw)
In-Reply-To: <d492226a12e04aa3baa02ae4975bb2dd@XCH-RTP-017.cisco.com>
Hi, Hanoch
Are you talking about i40 VF's latency? And you are using DPDK PF as host driver?
In this case, we are setting the Interrupt Throttling (ITR) to be maximum. That is to say, if the packet rate is very slow , the receive descriptor is written back when ITR timeout, otherwise it is written back when cache line is full (4 descriptors/packets). I think that's why you saw the latency is varying.
If we change the ITR to minor, then huge number of interrupts will coming to core which impact performance.
Thanks
Jingjing
From: Hanoch Haim (hhaim) [mailto:hhaim@cisco.com]
Sent: Friday, November 24, 2017 7:25 PM
To: dev@dpdk.org
Cc: Wu, Jingjing <jingjing.wu@intel.com>
Subject: RE: [dpdk-dev] net/i40e: latency issue due fix interrupt throttling setting in PF
Re-sending
Hanoh
From: Hanoch Haim (hhaim)
Sent: Monday, November 20, 2017 5:19 PM
To: dev@dpdk.org<mailto:dev@dpdk.org>
Cc: Wu, Jingjing (jingjing.wu@intel.com<mailto:jingjing.wu@intel.com>); Hanoch Haim (hhaim)
Subject: [dpdk-dev] net/i40e: latency issue due fix interrupt throttling setting in PF
Hi All,
While integrating dpdk17.11 into TRex latest code a new latency issue is observed (i40e is very sensitive because it has very good resolution due to Qos configuration).
git bitsec found the following commit.
With this commit we observe high spikes of Rx latency (~40usec) vs (~8usec).
Any idea why?
I can send how to reproduce this, it is very simple.
cfd662d22e7bddb4ba41dbd1384f8497f38c2b4e is the first bad commit
commit cfd662d22e7bddb4ba41dbd1384f8497f38c2b4e
Author: Jingjing Wu <jingjing.wu@intel.com<mailto:jingjing.wu@intel.com>>
Date: Thu Aug 24 09:57:51 2017 +0800
net/i40e: fix interrupt throttling setting in PF
As no matter the PF host driver is DPDK or other kernel drivers,
they are sharing the same virtchnnl interfaces to communicate to VFs.
To follow the generic interface, DPDK PF need to set Interrupt
Throttling (ITR) index according to the rxitr_idx from virtchnnl
instead of ITR_NONE.
Fixes: 6d59e4ea74a6 ("net/i40e: change version number to support Linux VF")
Cc: stable@dpdk.org<mailto:stable@dpdk.org>
Signed-off-by: Jingjing Wu <jingjing.wu@intel.com<mailto:jingjing.wu@intel.com>>
Thanks,
Hanoh
next prev parent reply other threads:[~2017-11-28 12:50 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-20 15:18 Hanoch Haim (hhaim)
2017-11-24 11:24 ` Hanoch Haim (hhaim)
2017-11-28 12:50 ` Wu, Jingjing [this message]
2017-11-28 13:14 ` Hanoch Haim (hhaim)
2017-11-28 15:01 ` Wu, Jingjing
2017-11-28 15:07 ` Hanoch Haim (hhaim)
2017-11-30 1:24 ` Wu, Jingjing
2017-11-30 16:47 ` Hanoch Haim (hhaim)
2017-11-30 17:46 ` Wu, Jingjing
2017-11-30 18:02 ` Hanoch Haim (hhaim)
2017-12-06 11:00 ` Xing, Beilei
2017-12-06 11:21 ` Hanoch Haim (hhaim)
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=9BB6961774997848B5B42BEC655768F810EC8AC3@SHSMSX103.ccr.corp.intel.com \
--to=jingjing.wu@intel.com \
--cc=dev@dpdk.org \
--cc=hhaim@cisco.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).