From owner-freebsd-scsi@FreeBSD.ORG Fri Jan 30 17:38:12 2015 Return-Path: Delivered-To: freebsd-scsi@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 66E5B7D7 for ; Fri, 30 Jan 2015 17:38:12 +0000 (UTC) Received: from nm5-vm6.bullet.mail.gq1.yahoo.com (nm5-vm6.bullet.mail.gq1.yahoo.com [98.136.218.181]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 2E7A2DE1 for ; Fri, 30 Jan 2015 17:38:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s2048; t=1422639485; bh=gZN+8ucR1i4g2/dsFmDTqkeuCHoOqABfeN+PI0e20zA=; h=Subject:From:In-Reply-To:Date:Cc:References:To:From:Subject; b=i8S90nCjRohkX5/spUSGDiFEs2KCGAsxP5pkNVY458A1zzh8/ewQIGEeH/KDVwiELiE9/es397LnF3Yps1Q0oO/n0W/ycU7AeM/Y35na53vuiWX7LCksXhc7cGxpmcfaRwn7w3GAgeGfuNn64MUIqk2I1Mfu/Y7jlfiv1MvCTcdiApmptwOCLsg1vZ66ov5BhJKZiz7RRfI3NTRl56pMNxwrOhQYjHhZBjX1rymrgsqZ28EsBolGx24aQBbwvM1eNiScjHgvF+SSpIjYp3nxuSJdeY6Dx0klMu8U1Al1eyhmbEMwIzRDHM7XwLYGiXAbbq/HoYxVwvVg3RSTHkAOyw== Received: from [98.137.12.59] by nm5.bullet.mail.gq1.yahoo.com with NNFMP; 30 Jan 2015 17:38:05 -0000 Received: from [208.71.42.193] by tm4.bullet.mail.gq1.yahoo.com with NNFMP; 30 Jan 2015 17:38:05 -0000 Received: from [127.0.0.1] by smtp204.mail.gq1.yahoo.com with NNFMP; 30 Jan 2015 17:38:05 -0000 X-Yahoo-Newman-Id: 233747.20230.bm@smtp204.mail.gq1.yahoo.com X-Yahoo-Newman-Property: ymail-3 X-YMail-OSG: Y.I3qTQVM1kedMIZI6pTM5iFvXANAN27AEQcHItcDGnrgmb bP6FKu93HP1GrdDciR2kaGcX3GStopvk.VMCrGSYZzxqIBEG4b9DjEynhCP8 JS6blZc9AzSdC7sNISbqCuVG.ZBMVFEZSuqorIkSmIPi7N1FteZAoTGiP.lh bzFkR0gphz4aLKcLhbOySRoV3uXMFB8s6ZVqTbyLQz37iMDDjOZDO.bijjwE jrY.69_IKo.vtRbG6FGqP1SFs6Sm4fw7n7vVayNTZOtNs.pLQJdq1VtEnNiq IcvLx3hijru.tDG.KSyFAL9OoNuPPfY4N50sgDOasMQFz8tS6VxK2M.Z4qQK uPlAwJANagYt_n.pgbTCyzOFY2uXoTmLz0yJXq4Ku4eRGdWNJD0CDHdxKSgN _K05JxwLAdG8GGpWa9NTbe_Op4vdxIqikueXw_EPbs2K9RqbJN7RfVaFw0dN awtbMWgGtC9J2vLzQ6F_W1MnEserf7a1u71V4rb29hZo4bpnnnsLCsC2YtZs r0WsHQ8SevZ6nea3tY4eALGTsyPf_3Ka_S49NAMrqng-- X-Yahoo-SMTP: clhABp.swBB7fs.LwIJpv3jkWgo2NU8- Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2070.6\)) Subject: Re: How to send 1MB I/O size in a single I/O request without split From: Scott Long In-Reply-To: <37dd5147bdbf0ea417d2fdfb31565358@mail.gmail.com> Date: Fri, 30 Jan 2015 10:38:03 -0700 Content-Transfer-Encoding: quoted-printable Message-Id: References: <8B56B74C-7EBC-4D1B-89AB-46DA8ED05DD5@yahoo.com> <923e4c2e65d29f2f39e0aa2f6d4ab38a@mail.gmail.com> <37dd5147bdbf0ea417d2fdfb31565358@mail.gmail.com> To: Sibananda Sahu X-Mailer: Apple Mail (2.2070.6) Cc: freebsd-scsi@freebsd.org X-BeenThere: freebsd-scsi@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: SCSI subsystem List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 30 Jan 2015 17:38:12 -0000 > On Jan 30, 2015, at 3:18 AM, Sibananda Sahu = wrote: >=20 > Hi Scott, >=20 > One more thing to ask. >=20 > I think even if I will modify the bus_dma_tag in our driver to have a = max > segment of 4K, the max I/O length per I/O request that will come is = 128KB > because of the MAXPHYS limitation. > I have tested this by restricting the MAXPHYS to 128KB again and when = I > requested an I/O with bs=3D1M the I/O was split with various length = I/O > requests. >=20 > Does this implies that tuning the MAXPHYS is the ultimate solution to = get > larger I/O size?? Yes. You will need to rebuild your kernel with the larger size. Some = day we might default to a larger size, or make it dynamic. Scott