netdev - Re: [PATCH net v3 3/3] bnxt_en: handle tpa

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Message-ID: <0bc60b9d-fbf7-4421-ab6a-5854355d68f4@davidwei.uk>
Date: Tue, 10 Dec 2024 10:14:53 -0800
From: David Wei <dw@...idwei.uk>
To: Yunsheng Lin <linyunsheng@...wei.com>, netdev@...r.kernel.org,
 Michael Chan <michael.chan@...adcom.com>,
 Andy Gospodarek <andrew.gospodarek@...adcom.com>,
 Somnath Kotur <somnath.kotur@...adcom.com>
Cc: Andrew Lunn <andrew+netdev@...n.ch>, "David S. Miller"
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
Subject: Re: [PATCH net v3 3/3] bnxt_en: handle tpa_info in queue API
 implementation

On 2024-12-10 04:25, Yunsheng Lin wrote:
> On 2024/12/4 12:10, David Wei wrote:
> 
>>  	bnxt_copy_rx_ring(bp, rxr, clone);
>> @@ -15563,6 +15580,8 @@ static int bnxt_queue_stop(struct net_device *dev, void *qmem, int idx)
>>  	bnxt_hwrm_rx_agg_ring_free(bp, rxr, false);
>>  	rxr->rx_next_cons = 0;
>>  	page_pool_disable_direct_recycling(rxr->page_pool);
>> +	if (bnxt_separate_head_pool())
>> +		page_pool_disable_direct_recycling(rxr->head_pool);
> 
> Hi, David
> As mentioned in [1], is the above page_pool_disable_direct_recycling()
> really needed?
> 
> Is there any NAPI API called in the implementation of netdev_queue_mgmt_ops?
> It doesn't seem obvious there is any NAPI API like napi_enable() &
> ____napi_schedule() that is called in bnxt_queue_start()/bnxt_queue_stop()/
> bnxt_queue_mem_alloc()/bnxt_queue_mem_free() through code reading.
> 
> 1. https://lore.kernel.org/all/c2b306af-4817-4169-814b-adbf25803919@huawei.com/

Hi Yunsheng, there are explicitly no napi_enable/disable() calls in the
bnxt implementation of netdev_queue_mgmt_ops due to ... let's say HW/FW
quirks. I looked back at my discussions w/ Broadcom, and IIU/RC
bnxt_hwrm_vnic_update() will prevent any work from coming into the rxq
that I'm trying to stop. Calling napi_disable() has unintended side
effects on the Tx side.

The intent of the call to page_pool_disable_direct_recycling() is to
prevent pages from the old page pool from being returned into the fast
cache. These pages must be returned via page_pool_return_page() so that
the it can eventually be freed in page_pool_release_retry().

I'm going to take a look at your discussions in [1] and respond there.