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 linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Message-ID: <253h6oxvlwd.fsf@nvidia.com> Date: Thu, 17 Aug 2023 16:28:02 +0300 From: Aurelien Aptel <aaptel@...dia.com> To: Sagi Grimberg <sagi@...mberg.me>, linux-nvme@...ts.infradead.org, netdev@...r.kernel.org, hch@....de, kbusch@...nel.org, axboe@...com, chaitanyak@...dia.com, davem@...emloft.net, kuba@...nel.org Cc: Boris Pismenny <borisp@...dia.com>, aurelien.aptel@...il.com, smalin@...dia.com, malin1024@...il.com, ogerlitz@...dia.com, yorayz@...dia.com, galshalom@...dia.com, mgurtovoy@...dia.com Subject: Re: [PATCH v12 08/26] nvme-tcp: Add DDP data-path Sagi Grimberg <sagi@...mberg.me> writes: >>>> @@ -1308,6 +1407,15 @@ static int nvme_tcp_try_send_cmd_pdu(struct nvme_tcp_request *req) >>>> else >>>> msg.msg_flags |= MSG_EOR; >>>> >>>> + if (test_bit(NVME_TCP_Q_OFF_DDP, &queue->flags)) { >>>> + ret = nvme_tcp_setup_ddp(queue, pdu->cmd.common.command_id, >>>> + blk_mq_rq_from_pdu(req)); >>>> + WARN_ONCE(ret, "ddp setup failed (queue 0x%x, cid 0x%x, ret=%d)", >>>> + nvme_tcp_queue_id(queue), >>>> + pdu->cmd.common.command_id, >>>> + ret); >>>> + } >>> >>> Any reason why this is done here when sending the command pdu and not >>> in setup time? >> >> We wish to interact with the HW from the same CPU per queue, hence we >> are calling setup_ddp() after queue->io_cpu == raw_smp_processor_id() >> was checked in nvme_tcp_queue_request(). > > That is very fragile. You cannot depend on this micro-optimization being > in the code. Is this related to a hidden steering rule you are adding > to the hw? We are using a steering rule in order to redirect packets into the offload engine. This rule also helps with aligning the nvme-tcp connection with a specific core. > Which reminds me, in the control patch, you are passing io_cpu, this is > also a dependency that should be avoided, you should use the same > mechanism as arfs to learn where the socket is being reaped. We can use queue->sock->sk->sk_incoming_cpu instead of queue->io_cpu as it is used in the nvme-tcp target.
Powered by blists - more mailing lists