Re: [RFC PATCH v8 00/19] virtio/vsock: introduce SOCK_SEQPACKET support

From: Stefano Garzarella <sgarzare@redhat.com>
To: Arseny Krasnov <arseny.krasnov@kaspersky.com>
Cc: Andra Paraschiv <andraprs@amazon.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"stsp2@yandex.ru" <stsp2@yandex.ru>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"virtualization@lists.linux-foundation.org"
	<virtualization@lists.linux-foundation.org>,
	"oxffffaa@gmail.com" <oxffffaa@gmail.com>,
	Norbert Slusarek <nslusarek@gmx.net>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	Colin Ian King <colin.king@canonical.com>,
	Jakub Kicinski <kuba@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Jorgen Hansen <jhansen@vmware.com>,
	Alexander Popov <alex.popov@linux.com>
Subject: Re: [RFC PATCH v8 00/19] virtio/vsock: introduce SOCK_SEQPACKET support
Date: Thu, 22 Apr 2021 12:02:17 +0200	[thread overview]
Message-ID: <20210422100217.jmpgevtrukqyukfo@steredhat> (raw)
In-Reply-To: <bfefdd94-a84f-8bed-331e-274654a7426f@kaspersky.com>

On Thu, Apr 22, 2021 at 12:40:17PM +0300, Arseny Krasnov wrote:
>On 22.04.2021 11:46, Stefano Garzarella wrote:
>> On Wed, Apr 21, 2021 at 06:06:28PM +0300, Arseny Krasnov wrote:
>>> Thank You, i'll prepare next version. Main question is: does this
>>> approach(no SEQ_BEGIN, SEQ_END, 'msg_len' and 'msg_id') considered
>>> good? In this case it will be easier to prepare final version, because
>>> is smaller and more simple than previous logic. Also patch to spec
>>> will be smaller.
>> Yes, it's definitely much better than before.
>>
>> The only problem I see is that we add some overhead per fragment
>> (header). We could solve that with the mergeable buffers that Jiang is
>> considering for DGRAM.
>
>If we are talking about receive, i think, i can reuse merge logic for

Yep, for TX the guest can potentially enqueue a big buffer.
Maybe it's still worth keeping a maximum size and fragmenting as we do 
now.

>
>stream sockets, the only difference is that buffers are mergeable
>until previous EOR(e.g. previous message) bit is found in rx queue.
>

I got a little lost.
Can you elaborate more?

Thanks,
Stefano

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