From owner-freebsd-hackers Thu Jun 3 7:51:45 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from sol (cs1-gw.cs.binghamton.edu [128.226.171.72]) by hub.freebsd.org (Postfix) with SMTP id 989F1153A5 for ; Thu, 3 Jun 1999 07:51:34 -0700 (PDT) (envelope-from zzhang@cs.binghamton.edu) Received: from localhost (zzhang@localhost) by sol (SMI-8.6/8.6.9) with SMTP id KAA28604 for ; Thu, 3 Jun 1999 10:40:11 -0400 Date: Thu, 3 Jun 1999 10:40:10 -0400 (EDT) From: Zhihui Zhang Reply-To: Zhihui Zhang To: freebsd-hackers@freebsd.org Subject: The choice of MAXPHYS Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG The value of MAXPHYS is chosen to be 64K for the maximum raw I/O transfer size. I am wondering why it is not set larger. The maxcontig value of FFS is default to be 16, which means 16*8192 or 128K bytes (twice as big as 64K) . If we raise the value of MAXPHYS, we can put more data blocks of a big file contiguously on the disk (perhaps even more than 16 blocks to achieve better performance). Am I right? Is there any limit of the value of MAXPHYS? Any help is appreciated. -Zhihui To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message