From owner-freebsd-net@freebsd.org Mon Jul 2 14:10:02 2018 Return-Path: Delivered-To: freebsd-net@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id BC70F102A98A for ; Mon, 2 Jul 2018 14:10:01 +0000 (UTC) (envelope-from rizzo.unipi@gmail.com) Received: from mailman.ysv.freebsd.org (mailman.ysv.freebsd.org [IPv6:2001:1900:2254:206a::50:5]) by mx1.freebsd.org (Postfix) with ESMTP id 50F878A587 for ; Mon, 2 Jul 2018 14:10:01 +0000 (UTC) (envelope-from rizzo.unipi@gmail.com) Received: by mailman.ysv.freebsd.org (Postfix) id 0FF34102A989; Mon, 2 Jul 2018 14:10:01 +0000 (UTC) Delivered-To: net@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id DA995102A988 for ; Mon, 2 Jul 2018 14:10:00 +0000 (UTC) (envelope-from rizzo.unipi@gmail.com) Received: from mail-it0-x230.google.com (mail-it0-x230.google.com [IPv6:2607:f8b0:4001:c0b::230]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 732968A582 for ; Mon, 2 Jul 2018 14:10:00 +0000 (UTC) (envelope-from rizzo.unipi@gmail.com) Received: by mail-it0-x230.google.com with SMTP id p4-v6so12307877itf.2 for ; Mon, 02 Jul 2018 07:10:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:sender:in-reply-to:references:from:date:message-id :subject:to:cc; bh=KOO08tjAUJj/T+JwGGhaJXAm+arIvqzW7jhIa69NKY0=; b=nQyyIQybMBEwrLiumdOKlwfuZAMEQV/PtEeGgAL2F8fzeDNQOZvG7aRx4s6e84lEhO HbMgnBV5zej2EyOvYPjDYdH8HtukxPOTHZJp+pHIU8sJsN/PFozLKaM0GV4hskJFqzOZ Nqh1qbpPcFoIsIqLKHrzt2Dye/THf89T8ygF8+SX9XrXjoAFGb2fAq8N0hekqdLhbqQ+ 4D4Uo70FTCLgujC0xXhxqfJayA7WIUABvfpE1jBqigniZ/CGq7gwxFd4iPEXfIdcXygm leaJrUi/uspzqOSTZte+BQsFDkiYpedF8L20scAUD04zdOHAaZSj0oEy6lfsBq0sUAbK QsEg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:sender:in-reply-to:references:from :date:message-id:subject:to:cc; bh=KOO08tjAUJj/T+JwGGhaJXAm+arIvqzW7jhIa69NKY0=; b=ixI0gNatZ1iBLHEUGLSONmkLgMwybeIYqzxsZlezwIhKi2GHz32i3H6NvNKGs1tzeM FhLnQvX8Rlqam6FMHbaSZY3ytdOGxnfA4TgdVXRtBoe3/Gs4eMZeJheIl/Lm+44YDzlm OEjOlBEKsX6v92NNMOxyPrzZ5w86dx9yPewr+zFj54kmh+YaYFB+stxS7PT789mWnOux kwDAMG0KSsC3DAt1cobW1IS5lJdogINuIPmNCgl1FqIt4RyPA1oMwwlY+a7eLcpnwv0G NGChtcWtYTp1G+xEfJIYZa70alxLkommekf9JTdPBuDT4k9PxJc1BBpq3E5fh3ErCfmw LWaw== X-Gm-Message-State: APt69E1OzKbmIIhIzGrMTadn7gLyeXqjFcXwvd9PGyWoM2Y/uNHeXrrS HtUlBkVfq/Dj8kEJ5P8GCf1EsiS0C3j6S6wPxhc= X-Google-Smtp-Source: AAOMgpeojWzl/5/3IIcBWd5omRJgJiX4P4wtSa7zMOHP6xAclRvZNNyKL+XZho0ytMnhKbG56VQDSdPpzPnr1c+CRxE= X-Received: by 2002:a24:2555:: with SMTP id g82-v6mr9838751itg.108.1530540599775; Mon, 02 Jul 2018 07:09:59 -0700 (PDT) MIME-Version: 1.0 Sender: rizzo.unipi@gmail.com Received: by 2002:a6b:9f01:0:0:0:0:0 with HTTP; Mon, 2 Jul 2018 07:09:59 -0700 (PDT) In-Reply-To: References: From: Luigi Rizzo Date: Mon, 2 Jul 2018 16:09:59 +0200 X-Google-Sender-Auth: uQWeYjZ1CVOKiow6e1gjeLP41AM Message-ID: Subject: Re: Regarding latency of Netmap i/o To: Suneet Singh Cc: "freebsd-net@freebsd.org" Content-Type: text/plain; charset="UTF-8" X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.27 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 02 Jul 2018 14:10:02 -0000 On Mon, Jul 2, 2018 at 1:34 AM, Suneet Singh wrote: > Dear Professor, > > I am Suneet from India. I am a PhD student in Unicamp, Campinas, Brazil. I > am testing latency of MACSAD P4 software switch. I found that latency using > netmap i/o is higher than using socket_mmap i/o while in case of dpdk, > latency is very low. please quantify the latency the type of experiment you run, the system's configuration and the latency figures that you are seeing because 'higher' and 'very low' mean nothing without context. Batching is almost never a reason for significantly higher latency unless it is misused. Typically there are mistakes in setting up the experiment that cause higher latency than expected cheers luigi > > As I read the research papers related to netmap, I found that it may be the > reason of high latency in case of netmap compare to socket_mmap due to batch > process. > > However, I am not sure why latency of my switch is higher using netmap > compare to sockte mmap. I am requesting you to please let me know the > performance of netmap interms of latency (end-to-end) compare to > socket_mmap. > > Thank you so much for your precious time. > > " Man needs his difficulties because they are necessary to enjoy success." > > Kind Regards > Suneet Kumar Singh > > https://www.researchgate.net/profile/Suneet_Singh7 -- -----------------------------------------+------------------------------- Prof. Luigi RIZZO, rizzo@iet.unipi.it . Dip. di Ing. dell'Informazione http://www.iet.unipi.it/~luigi/ . Universita` di Pisa TEL +39-050-2217533 . via Diotisalvi 2 Mobile +39-338-6809875 . 56122 PISA (Italy) -----------------------------------------+-------------------------------