patches for DPDK stable branches
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From: Long Li <longli@microsoft.com>
To: Wei Hu <weh@microsoft.com>, "dev@dpdk.org" <dev@dpdk.org>
Cc: "stable@dpdk.org" <stable@dpdk.org>,
	Ferruh Yigit <ferruh.yigit@amd.com>,
	 Luca Boccassi <bluca@debian.org>,
	Kevin Traynor <ktraynor@redhat.com>
Subject: RE: [PATCH 1/1] net/mana: add 32 bit short doorbell
Date: Tue, 19 Sep 2023 19:23:39 +0000	[thread overview]
Message-ID: <PH7PR21MB32635BBA4B835FF5CE65D185CEFAA@PH7PR21MB3263.namprd21.prod.outlook.com> (raw)
In-Reply-To: <SI2P153MB0441E7A9C6D7CF9882E5AA16BBFAA@SI2P153MB0441.APCP153.PROD.OUTLOOK.COM>

> > > +#ifdef RTE_ARCH_32
> > > +	uint16_t cqe_incr = (uint16_t)rxq->gdma_cq.head_incr_to_short_db;
> >
> > How do you make sure head_incr_to_short_db doesn't overflow?
> >
> 
> I have checked this with hardware team. In my opinion it would be easily
> overflown.
> The hw team seems suggesting the hw will take care of this.
> 
> Thanks,
> Wei

I'm not sure how HW can take care of this when it overflows. When it happens, the HW will miss a doorbell and CQ queue will get full. And eventually you'll lose completions for TX/RX.

In mana_alloc_and_post_rx_wqes() and mana_rx_burst(), the code has check for RX/TX_WQE_SHORT_DB_THRESHOLD to make sure tail_incr doesn't overflow when ringing the doorbell.

In gdma_poll_completion_queue(), you need to have a similar mechanism to not overflow tail_incr  when ringing the doorbell.

Thanks,

Long

  reply	other threads:[~2023-09-19 19:23 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-09 12:23 Wei Hu
2023-09-13 21:11 ` Long Li
2023-09-14  5:11   ` Wei Hu
2023-09-18 18:02 ` Ferruh Yigit
2023-09-19  3:38   ` Wei Hu
2023-09-19 11:27     ` Ferruh Yigit
2023-09-20  3:11       ` Wei Hu
2023-09-18 20:01 ` Long Li
2023-09-19  2:13   ` Wei Hu
2023-09-19 19:23     ` Long Li [this message]
2023-09-20  8:10       ` Wei Hu
2023-09-20 17:28         ` Long Li

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