lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Mon, 7 Dec 2020 17:42:14 -0700 From: David Ahern <dsahern@...il.com> To: Boris Pismenny <borisp@...lanox.com>, kuba@...nel.org, davem@...emloft.net, saeedm@...dia.com, hch@....de, sagi@...mberg.me, axboe@...com, kbusch@...nel.org, viro@...iv.linux.org.uk, edumazet@...gle.com Cc: boris.pismenny@...il.com, linux-nvme@...ts.infradead.org, netdev@...r.kernel.org, benishay@...dia.com, ogerlitz@...dia.com, yorayz@...dia.com, Ben Ben-Ishay <benishay@...lanox.com>, Or Gerlitz <ogerlitz@...lanox.com>, Yoray Zack <yorayz@...lanox.com> Subject: Re: [PATCH v1 net-next 02/15] net: Introduce direct data placement tcp offload On 12/7/20 2:06 PM, Boris Pismenny wrote: > This commit introduces direct data placement offload for TCP. > This capability is accompanied by new net_device operations that > configure > hardware contexts. There is a context per socket, and a context per DDP > opreation. Additionally, a resynchronization routine is used to assist > hardware handle TCP OOO, and continue the offload. > Furthermore, we let the offloading driver advertise what is the max hw > sectors/segments. > > Using this interface, the NIC hardware will scatter TCP payload directly > to the BIO pages according to the command_id. > To maintain the correctness of the network stack, the driver is expected > to construct SKBs that point to the BIO pages. > > This, the SKB represents the data on the wire, while it is pointing > to data that is already placed in the destination buffer. > As a result, data from page frags should not be copied out to > the linear part. > > As SKBs that use DDP are already very memory efficient, we modify > skb_condence to avoid copying data from fragments to the linear > part of SKBs that belong to a socket that uses DDP offload. > > A follow-up patch will use this interface for DDP in NVMe-TCP. > You call this Direct Data Placement - which sounds like a marketing name. Fundamentally, this starts with offloading TCP socket buffers for a specific flow, so generically a TCP Rx zerocopy for kernel stack managed sockets (as opposed to AF_XDP's zerocopy). Why is this not building in that level of infrastructure first and adding ULPs like NVME on top?
Powered by blists - more mailing lists