From: Guilherme Piccoli <gpiccoli@canonical.com>
To: Sudarsana Reddy Kalluru <skalluru@marvell.com>
Cc: GR-everest-linux-l2 <GR-everest-linux-l2@marvell.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
Ariel Elior <aelior@marvell.com>,
"jay.vosburgh@canonical.com" <jay.vosburgh@canonical.com>
Subject: Re: [EXT] [PATCH V2] bnx2x: Prevent ptp_task to be rescheduled indefinitely
Date: Tue, 25 Jun 2019 09:55:30 -0300 [thread overview]
Message-ID: <CAHD1Q_y7v5fVeDRT+KDimQ-RBJMujMCL2DPvdBh==YEJ3+2ZaQ@mail.gmail.com> (raw)
In-Reply-To: <MN2PR18MB2528BCB89AC93EB791446BABD3E30@MN2PR18MB2528.namprd18.prod.outlook.com>
On Tue, Jun 25, 2019 at 1:02 AM Sudarsana Reddy Kalluru
<skalluru@marvell.com> wrote:
>
> Thanks for your changes and time on this. In general time-latching happens in couple or more milliseconds (even in some 100s of usec) under the normal traffic conditions. With this approach, there's a possibility that every packet has to wait for atleast 50ms for the timestamping. This in turn affects the wait-queue (of packets to be timestamped) at hardware as next TS recording happens only after the register is freed/read. And also, it incurs some latency for the ptp applications.
>
> PTP thread is consuming time may be due to the debug messages in this error path, which you are planning address already (thanks!!).
> "Also, I've dropped the PTP "outstanding, etc" messages to debug-level, they're quite flooding my log.
> Do you see cpu hog even after removing this message? In such case we may need to think of other alternatives such as sleep for 1 ms.
> Just for the info, the approach continuous-poll-for-timestamp() is used ixgbe driver (ixgbe_ptp_tx_hwtstamp_work()) as well.
>
Thanks again for the good insights Sudarsana! I'll do some experiments
dropping all messages and checking
if the ptp thread is still consuming a lot of CPU (I believe so). In
this case, I'll rework the approach by starting
the delays in 1ms to avoid impacting the HW wait-queue and causing
delays in ptp applications.
Cheers,
Guilherme
next prev parent reply other threads:[~2019-06-25 12:56 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-24 22:23 [PATCH V2] bnx2x: Prevent ptp_task to be rescheduled indefinitely Guilherme G. Piccoli
2019-06-25 4:01 ` [EXT] " Sudarsana Reddy Kalluru
2019-06-25 12:55 ` Guilherme Piccoli [this message]
2019-06-25 20:25 ` Guilherme Piccoli
2019-06-26 8:25 ` Sudarsana Reddy Kalluru
2019-06-26 20:24 ` Guilherme Piccoli
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