From: Jakub Kicinski <kuba@kernel.org>
To: Haiyang Zhang <haiyangz@microsoft.com>
Cc: "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
Dexuan Cui <decui@microsoft.com>,
KY Srinivasan <kys@microsoft.com>,
Paul Rosswurm <paulros@microsoft.com>,
"olaf@aepfle.de" <olaf@aepfle.de>,
"vkuznets@redhat.com" <vkuznets@redhat.com>,
"davem@davemloft.net" <davem@davemloft.net>,
"wei.liu@kernel.org" <wei.liu@kernel.org>,
"edumazet@google.com" <edumazet@google.com>,
"pabeni@redhat.com" <pabeni@redhat.com>,
"leon@kernel.org" <leon@kernel.org>,
Long Li <longli@microsoft.com>,
"ssengar@linux.microsoft.com" <ssengar@linux.microsoft.com>,
"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
"daniel@iogearbox.net" <daniel@iogearbox.net>,
"john.fastabend@gmail.com" <john.fastabend@gmail.com>,
"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
"ast@kernel.org" <ast@kernel.org>,
Ajay Sharma <sharmaajay@microsoft.com>,
"hawk@kernel.org" <hawk@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH V3,net-next, 3/4] net: mana: Enable RX path to handle various MTU sizes
Date: Mon, 17 Apr 2023 10:52:29 -0700 [thread overview]
Message-ID: <20230417105229.7d1eb988@kernel.org> (raw)
In-Reply-To: <PH7PR21MB3116023068CFA8D600FA5B18CA9E9@PH7PR21MB3116.namprd21.prod.outlook.com>
On Sat, 15 Apr 2023 14:25:29 +0000 Haiyang Zhang wrote:
> > Allocating frag larger than a page is not safe.
>
> I saw other drivers doing this - use napi_alloc_frag for size bigger than a page.
> And it returns compound page. Why it's not safe? Should we use other allocator
> when need compound pages?
I believe so. There was a thread about this within the last year.
Someone was trying to fix the page frag allocator to not fall back
to order 0 pages in case of failure if requested size is > PAGE_SIZE.
But there was push back and folks were saying that it's simply not
a case supported by the frag allocator. 🤷️
> > Frag allocator falls back to allocating single pages, doesn't it?
>
> Actually I checked it. Compound page is still returned for size smaller than PAGE_SIZE,
> so I used single page allocation for that.
https://elixir.bootlin.com/linux/v6.3-rc6/source/mm/page_alloc.c#L5723
Jumbo frames should really be supported as scatter transfers,
if possible.
next prev parent reply other threads:[~2023-04-17 17:52 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-12 21:15 [PATCH V3,net-next, 0/4] net: mana: Add support for jumbo frame Haiyang Zhang
2023-04-12 21:16 ` [PATCH V3,net-next, 1/4] net: mana: Use napi_build_skb in RX path Haiyang Zhang
2023-04-12 21:16 ` [PATCH V3,net-next, 2/4] net: mana: Refactor RX buffer allocation code to prepare for various MTU Haiyang Zhang
2023-04-13 13:04 ` Leon Romanovsky
2023-04-13 14:03 ` Haiyang Zhang
2023-04-13 16:30 ` Leon Romanovsky
2023-04-13 16:40 ` Jakub Kicinski
2023-04-13 16:59 ` Leon Romanovsky
2023-04-13 17:01 ` Jakub Kicinski
2023-04-15 2:04 ` Jakub Kicinski
2023-04-15 14:09 ` Haiyang Zhang
2023-04-12 21:16 ` [PATCH V3,net-next, 3/4] net: mana: Enable RX path to handle various MTU sizes Haiyang Zhang
2023-04-15 2:06 ` Jakub Kicinski
2023-04-15 14:25 ` Haiyang Zhang
2023-04-17 17:52 ` Jakub Kicinski [this message]
2023-04-17 19:52 ` Haiyang Zhang
2023-04-12 21:16 ` [PATCH V3,net-next, 4/4] net: mana: Add support for jumbo frame Haiyang Zhang
2023-04-15 2:08 ` [PATCH V3,net-next, 0/4] " Jakub Kicinski
2023-04-15 14:11 ` Haiyang Zhang
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