From: Julian Wiedmann <jwiedmann.dev@gmail.com>
To: Hyeonggon Yoo <42.hyeyoo@gmail.com>, netdev@vger.kernel.org
Cc: Shay Agroskin <shayagr@amazon.com>,
Arthur Kiyanovski <akiyano@amazon.com>,
David Arinzon <darinzon@amazon.com>,
Noam Dagan <ndagan@amazon.com>, Saeed Bishara <saeedb@amazon.com>,
"David S . Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Sameeh Jubran <sameehj@amazon.com>,
Wei Yongjun <weiyongjun1@huawei.com>,
Lorenzo Bianconi <lorenzo@kernel.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] net: ena: Do not waste napi skb cache
Date: Mon, 24 Jan 2022 11:29:52 +0200 [thread overview]
Message-ID: <5cca8bdd-bed0-f26a-6c96-d18947d3a50b@gmail.com> (raw)
In-Reply-To: <f835cbb3-a028-1daf-c038-516dd47ce47c@gmail.com>
On 24.01.22 10:57, Julian Wiedmann wrote:
> On 23.01.22 13:56, Hyeonggon Yoo wrote:
>> By profiling, discovered that ena device driver allocates skb by
>> build_skb() and frees by napi_skb_cache_put(). Because the driver
>> does not use napi skb cache in allocation path, napi skb cache is
>> periodically filled and flushed. This is waste of napi skb cache.
>>
>> As ena_alloc_skb() is called only in napi, Use napi_build_skb()
>> instead of build_skb() to when allocating skb.
>>
>> This patch was tested on aws a1.metal instance.
>>
>> Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
>> ---
>> drivers/net/ethernet/amazon/ena/ena_netdev.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.c b/drivers/net/ethernet/amazon/ena/ena_netdev.c
>> index c72f0c7ff4aa..2c67fb1703c5 100644
>> --- a/drivers/net/ethernet/amazon/ena/ena_netdev.c
>> +++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c
>> @@ -1407,7 +1407,7 @@ static struct sk_buff *ena_alloc_skb(struct ena_ring *rx_ring, void *first_frag)
>> skb = netdev_alloc_skb_ip_align(rx_ring->netdev,
>> rx_ring->rx_copybreak);
>
> To keep things consistent, this should then also be napi_alloc_skb().
>
And on closer look, this copybreak path also looks buggy. If rx_copybreak
gets reduced _while_ receiving a frame, the allocated skb can end up too
small to take all the data.
@ ena maintainers: can you please fix this?
>> else
>> - skb = build_skb(first_frag, ENA_PAGE_SIZE);
>> + skb = napi_build_skb(first_frag, ENA_PAGE_SIZE);
>>
>> if (unlikely(!skb)) {
>> ena_increase_stat(&rx_ring->rx_stats.skb_alloc_fail, 1,
>
next prev parent reply other threads:[~2022-01-24 9:30 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-23 11:56 [PATCH] net: ena: Do not waste napi skb cache Hyeonggon Yoo
2022-01-24 8:57 ` Julian Wiedmann
2022-01-24 9:29 ` Julian Wiedmann [this message]
2022-01-24 20:50 ` Shay Agroskin
2022-01-25 9:34 ` Hyeonggon Yoo
2022-01-25 13:50 ` Julian Wiedmann
2022-01-29 8:56 ` Hyeonggon Yoo
2022-01-25 13:45 ` Julian Wiedmann
2022-01-26 13:16 ` [PATCH v2] " Hyeonggon Yoo
2022-01-26 15:16 ` Shay Agroskin
2022-01-26 15:52 ` Jakub Kicinski
2022-01-29 8:55 ` Hyeonggon Yoo
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