From nobody Wed Oct 5 21:41:13 2022 X-Original-To: freebsd-hackers@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4MjSgq0Wl0z4f88X for ; Wed, 5 Oct 2022 21:41:27 +0000 (UTC) (envelope-from wlosh@bsdimp.com) Received: from mail-ej1-x629.google.com (mail-ej1-x629.google.com [IPv6:2a00:1450:4864:20::629]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "smtp.gmail.com", Issuer "GTS CA 1D4" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4MjSgp2hjmz3Hrr for ; Wed, 5 Oct 2022 21:41:26 +0000 (UTC) (envelope-from wlosh@bsdimp.com) Received: by mail-ej1-x629.google.com with SMTP id b2so541294eja.6 for ; Wed, 05 Oct 2022 14:41:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bsdimp-com.20210112.gappssmtp.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=p7Ytw52+sj6uEblG7xdDg/P5LQixYdCDfjMZ/0Q4e9k=; b=cd9AGrbD0xh5ue0WshICoAlscTbCpFBKbJCIjJyGjrDxjUZgvEmz3tbmfqTrM6JXTu xe1XFaktJFkk98QgMiuudI8fjOeuslEeQaAuERBgK+d04kBGctVWIB1tmx0yOIXEHFd/ HDkmHJ+OUvqml7ERsA280iewgpMGX7Bb/vYdyUb7VrfJxh6MEyFlv9jtATrk4tRsT9M4 hAGoLftQxe2vFimhx9cRi6I/8F1thiL5XRrkppd0WT8EPHiShpeOZ1hbxD1sUKp0aWep DWT3zIUIhty6XGFiy5J4XTZEZQtVLUrn6nqCiiklg2j7OVXge7UlWLv0Mn/7zwA33kAk fuww== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=p7Ytw52+sj6uEblG7xdDg/P5LQixYdCDfjMZ/0Q4e9k=; b=44YQWKfnvqoLnvSp+booDRP0JegD/KOCg7SeUhjb4R+gLf7vn1k7OQGIV1xL2MiOH8 UPTeJJ4P9oq4HLzzYiS0OGY+2HpcbmJvQlZYcstFdz0bimIIv2aWFDIyoyG+tg9jfctR mnYDs+8vC4nrK5VQsh0UsMZT2xKcjQcgJb3h01jaBbcHq+E1sTTdLjYXE3k4Xqwn17sm WzE0/FG3H3VVfY3kOMlRd4tFE0UOJB0cpZ3Kq2RU8QyWloxXOvtjSRIEc8m6djhmBLg2 oYQOKCx8qKb5eceQ3/d6Ta61X+zYylck/l8lautVCv7rxGuutGEeGOIrHeqr6XtnoBuR ScJw== X-Gm-Message-State: ACrzQf1SXwTCFvtcWh7gz/OUrTSfgct2+W00GHXubDPWTXyP94WaMXs0 LZJptGP7Cl28Z4k2FE72MoNdJ+ELGoF+hTCOSv0ARe24EaE= X-Google-Smtp-Source: AMsMyM7vc/l4lOxuvMfe6pHfR2tflXMBEnIYSIsaCD6PCe2CzTmjZQXA53exfq1jpJR5Pa6qHcYzx6EOYSxCEMWquUI= X-Received: by 2002:a17:907:6e28:b0:78d:20d7:1431 with SMTP id sd40-20020a1709076e2800b0078d20d71431mr1297404ejc.333.1665006085067; Wed, 05 Oct 2022 14:41:25 -0700 (PDT) List-Id: Technical discussions relating to FreeBSD List-Archive: https://lists.freebsd.org/archives/freebsd-hackers List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-hackers@freebsd.org MIME-Version: 1.0 References: <1cede94a-c114-17fa-a81c-bb58c2b5879c@freebsd.org> <750a38c-2c86-a571-eb65-f63998b7649f@puchar.net> <3999539a33b13a2843ae50b5ba3c44fa@gundo.com> In-Reply-To: <3999539a33b13a2843ae50b5ba3c44fa@gundo.com> From: Warner Losh Date: Wed, 5 Oct 2022 15:41:13 -0600 Message-ID: Subject: Re: Block sizes for dd(1) to USB memory sticks (flash drives) for installers for FreeBSD To: Pau Amma Cc: freebsd-hackers@freebsd.org Content-Type: multipart/alternative; boundary="0000000000003fefde05ea5070ad" X-Rspamd-Queue-Id: 4MjSgp2hjmz3Hrr X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org; dkim=pass header.d=bsdimp-com.20210112.gappssmtp.com header.s=20210112 header.b=cd9AGrbD; dmarc=none; spf=none (mx1.freebsd.org: domain of wlosh@bsdimp.com has no SPF policy when checking 2a00:1450:4864:20::629) smtp.mailfrom=wlosh@bsdimp.com X-Spamd-Result: default: False [-3.00 / 15.00]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-1.00)[-1.000]; FORGED_SENDER(0.30)[imp@bsdimp.com,wlosh@bsdimp.com]; R_DKIM_ALLOW(-0.20)[bsdimp-com.20210112.gappssmtp.com:s=20210112]; MIME_GOOD(-0.10)[multipart/alternative,text/plain]; MLMMJ_DEST(0.00)[freebsd-hackers@freebsd.org]; R_SPF_NA(0.00)[no SPF record]; ARC_NA(0.00)[]; RCVD_TLS_LAST(0.00)[]; MIME_TRACE(0.00)[0:+,1:+,2:~]; RCVD_COUNT_TWO(0.00)[2]; RCVD_IN_DNSWL_NONE(0.00)[2a00:1450:4864:20::629:from]; DKIM_TRACE(0.00)[bsdimp-com.20210112.gappssmtp.com:+]; ASN(0.00)[asn:15169, ipnet:2a00:1450::/32, country:US]; TO_DN_SOME(0.00)[]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_TWO(0.00)[2]; PREVIOUSLY_DELIVERED(0.00)[freebsd-hackers@freebsd.org]; TO_MATCH_ENVRCPT_SOME(0.00)[]; DMARC_NA(0.00)[bsdimp.com]; FROM_NEQ_ENVFROM(0.00)[imp@bsdimp.com,wlosh@bsdimp.com] X-ThisMailContainsUnwantedMimeParts: N --0000000000003fefde05ea5070ad Content-Type: text/plain; charset="UTF-8" On Wed, Oct 5, 2022 at 6:10 AM Pau Amma wrote: > On 2022-10-03 08:26, Wojciech Puchar wrote: > >> and > >> elsewhere: > >> > >> bs=1m > >> > >> Why so small? > > I've just checked. 128kB, 1MB and 4MB makes no noticable difference > > I remember someone in #freebsd (memory says debdrup) saying 128K is the > largest amount FreeBSD will write to a file or device as a single unit. maxphys used to be 128k. That changed in 13 to be 1MB (though it can be as large as 8MB). However, the maximum transfer size often is 256k or 512k for USB thumb drives and in the cases where it's less than 1MB, we'll do less. Warner --0000000000003fefde05ea5070ad Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


=
On Wed, Oct 5, 2022 at 6:10 AM Pau Am= ma <pauamma@gundo.com> wrote= :
On 2022-10-03 = 08:26, Wojciech Puchar wrote:
>> <https://www.freebsd.org/r= eleases/13.1R/announce/#_availability> and
>> elsewhere:
>>
>> bs=3D1m
>>
>> Why so small?
> I've just checked. 128kB, 1MB and 4MB makes no noticable differenc= e

I remember someone in #freebsd (memory says debdrup) saying 128K is the largest amount FreeBSD will write to a file or device as a single unit.

maxphys used to be 128k. That changed in 13 to= be 1MB (though it can be as large
as 8MB).=C2=A0

<= /div>
However, the maximum transfer size often is 256k or 512k for USB = thumb drives
and in the cases where it's less than 1MB, we= 9;ll do less.

Warner
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