From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by passt.top (Postfix) with ESMTP id 3675E5A0275 for ; Fri, 8 Mar 2024 09:55:22 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1709888121; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=XlI1VM2imdPUA8IFybHOzC1Lw2nNC8O7HLF9JH3KNGA=; b=dHCDOXDIsSF0M6FHLTJyKo3nSRxuk/lnJCg5Ut6P7Bq5IPToa5fOQs8us7pf3AjwEXPqX1 I7z1o+AsWIeblFZwpzOvIe5r0On8bVvWDEDeWlacKpX1RXq2pgLiSnrdCfGCrZaH6CEPhk malujWG+2RN+Y+N7v3W5zQ5WwdFpVv4= Received: from mail-lf1-f72.google.com (mail-lf1-f72.google.com [209.85.167.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-458-v9jfqCOgNkWvx6XW7X7AQw-1; Fri, 08 Mar 2024 03:55:19 -0500 X-MC-Unique: v9jfqCOgNkWvx6XW7X7AQw-1 Received: by mail-lf1-f72.google.com with SMTP id 2adb3069b0e04-5131aa087beso498843e87.2 for ; Fri, 08 Mar 2024 00:55:19 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1709888118; x=1710492918; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=XlI1VM2imdPUA8IFybHOzC1Lw2nNC8O7HLF9JH3KNGA=; b=cvUnlmQX9Xl+NWdmdrwz24XPUCprjxtgQccuH7cR/O0X55BM+xGXUZeThHzwr8YyHS xLCWhP8MzHmTcB6Kpcqj3AxElOu2VcIYrHCxAiwCYpM3DqYzqgiLWGZGdLO5z8XwA+KF xJ6NuQpjLvC5kEo8ceplMMVnKDiekGwohHhURbcFzFrLZOIOf4wBSm45gnAcip2wZ81z kfPWoZuWnb5YbVk5QPLIR8ZN+u6PzNMowCU2bpdxx5hJo6L78cEdm/3QFUfB1UNqY/eZ 8O5u6M0o2+SqVxtQwN0+qI7ooQWXiIDgfwUVs7dJh9oYZBsfkOiASZ7s/GanBLBxOrwa fO6A== X-Forwarded-Encrypted: i=1; AJvYcCUipZOZGFjvqn3OBm0RkTfppE3oZMNu6c/dJ4Ifey7Jc9kjnxnp8U74OJ3xUdSpymhYoh1ZXVcSRB7+krt75Zg8ePOS X-Gm-Message-State: AOJu0YynsJZjxEVhHoC7IPgLtuxin8g4a3sCXze3XCbhrCX4tzUQ/0Kt 5NDw4SCbNDjccK2ISkC6lKEHcXCHyhpNbUezhxdPkc6j1SMS97iB7S9itOudw4+8q/cWYuDyzJx DV556i9Bw1dPfuATImytlNAZA/YmyhCyqozKmGA5/zrLVemXjzg== X-Received: by 2002:a19:7407:0:b0:512:d5e4:1aa4 with SMTP id v7-20020a197407000000b00512d5e41aa4mr3030309lfe.60.1709888117916; Fri, 08 Mar 2024 00:55:17 -0800 (PST) X-Google-Smtp-Source: AGHT+IH9/7WJkzoHSByZR0ZFcOZcUPi9YqyYoDL8OSGaRCuPIWG/fE4O8Zq2JRQFTLSzU0Vs8divog== X-Received: by 2002:a19:7407:0:b0:512:d5e4:1aa4 with SMTP id v7-20020a197407000000b00512d5e41aa4mr3030292lfe.60.1709888117533; Fri, 08 Mar 2024 00:55:17 -0800 (PST) Received: from [192.168.100.30] ([82.142.8.70]) by smtp.gmail.com with ESMTPSA id bw1-20020a0560001f8100b0033db0c866f7sm22728548wrb.11.2024.03.08.00.55.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 08 Mar 2024 00:55:17 -0800 (PST) Message-ID: <3cb340b5-2227-4f44-9c60-b50c8b8fde43@redhat.com> Date: Fri, 8 Mar 2024 09:55:16 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/4] Some improvements to the tap send path To: Stefano Brivio References: <20240308065325.2181322-1-david@gibson.dropbear.id.au> <348a52c9-7c07-4150-b594-4743c7775be6@redhat.com> <20240308093404.3328ad2a@elisabeth> From: Laurent Vivier In-Reply-To: <20240308093404.3328ad2a@elisabeth> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Message-ID-Hash: 47HOS6HL7FZXICPDW4HDWS7WDZ6DWOHN X-Message-ID-Hash: 47HOS6HL7FZXICPDW4HDWS7WDZ6DWOHN X-MailFrom: lvivier@redhat.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: David Gibson , passt-dev@passt.top X-Mailman-Version: 3.3.8 Precedence: list List-Id: Development discussion and patches for passt Archived-At: Archived-At: List-Archive: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: On 3/8/24 09:34, Stefano Brivio wrote: > On Fri, 8 Mar 2024 09:18:48 +0100 > Laurent Vivier wrote: > >> On 3/8/24 07:53, David Gibson wrote: >>> This series has a handful of small improvements to the tap send path. >>> See individual commit messages for the details. >>> >>> I expect this will conflict with Laurent's upcoming work. I hope the >>> conflicts won't be too bad, and indeed will set us up for less >>> duplication there in the end. >> >> I'm working on patch that devides TCP buffers in several buffers pointed out by an IOV >> arrays and then provided to tap_send_frames(). I'm going to base my patch on this series. >> >> The idea is: >> >> A frame is made with 4 iovecs: >> >> #define TCP_IOV_VNET 0 >> #define TCP_IOV_ETH 1 >> #define TCP_IOV_IP 2 >> #define TCP_IOV_PAYLOAD 3 >> #define TCP_IOV_NUM 4 >> typedef struct iovec tap_iovec_t[TCP_IOV_NUM]; > > Except for the typedef :) (I'm actively trying to discourage them) ok... > ...this looks very neat. > > I would suggest that as soon as you have something barely spitting out > pseudo-correct bytes, you give it a try with perf(1). I'm quite > concerned that we might end up killing throughput, especially without > vhost-user, even though in theory it all sounds nice and byte-saving. > I hope to have something to test today... Thanks, Laurent