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From: Stephen Hemminger <stephen@networkplumber.org>
To: Yangchao Zhou <zhouyates@gmail.com>
Cc: dev@dpdk.org, Hemant@freescale.com, stable@dpdk.org
Subject: Re: [PATCH v2] kni: fix possible alloc_q starvation when mbufs are exhausted
Date: Wed, 9 Nov 2022 08:39:09 -0800	[thread overview]
Message-ID: <20221109083909.6536bce8@hermes.local> (raw)
In-Reply-To: <20221109060434.2012064-1-zhouyates@gmail.com>

On Wed,  9 Nov 2022 14:04:34 +0800
Yangchao Zhou <zhouyates@gmail.com> wrote:

> In some scenarios, mbufs returned by rte_kni_rx_burst are not freed
> immediately. So kni_allocate_mbufs may be failed, but we don't know.
> 
> Even worse, when alloc_q is completely exhausted, kni_net_tx in
> rte_kni.ko will drop all tx packets. kni_allocate_mbufs is never
> called again, even if the mbufs are eventually freed.
> 
> In this patch, we always try to allocate mbufs for alloc_q.
> 
> Don't worry about alloc_q being allocated too many mbufs, in fact,
> the old logic will gradually fill up alloc_q.
> Also, the cost of more calls to kni_allocate_mbufs should be acceptable.
> 
> Fixes: 3e12a98fe397 ("kni: optimize Rx burst")
> Cc: Hemant@freescale.com
> Cc: stable@dpdk.org
> 
> Signed-off-by: Yangchao Zhou <zhouyates@gmail.com>

Since fifo_get returning 0 (no buffers) is very common would this
change impact performance.

If the problem is pool draining might be better to make the pool
bigger.

  reply	other threads:[~2022-11-09 16:39 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-09  5:13 [PATCH] " Yangchao Zhou
2022-11-09  6:04 ` [PATCH v2] " Yangchao Zhou
2022-11-09 16:39   ` Stephen Hemminger [this message]
2022-11-11  9:12     ` Matt
2022-12-09 16:15       ` Ferruh Yigit
2022-12-30  4:23   ` [PATCH v3] " Yangchao Zhou
2023-01-03 12:47     ` Ferruh Yigit
2023-01-04 11:57       ` Matt
2023-01-04 14:34         ` Ferruh Yigit
2023-03-11  9:16           ` Thomas Monjalon

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