From owner-freebsd-hackers Mon Jun 7 11:44:42 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 8186014BCF for ; Mon, 7 Jun 1999 11:44:33 -0700 (PDT) (envelope-from zzhang@cs.binghamton.edu) Received: from localhost (zzhang@localhost) by sol (SMI-8.6/8.6.9) with SMTP id OAA12367 for ; Mon, 7 Jun 1999 14:33:07 -0400 Date: Mon, 7 Jun 1999 14:33:07 -0400 (EDT) From: Zhihui Zhang To: freebsd-hackers@freebsd.org Subject: help with I/O optimization with object 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 While studying the file ufs_readwrite.c, I see routines like uiomoveco() that calls vm_uiomove() in vm_map.c. I am almost sure that these are new in FreeBSD 3.x. The comment in ffs_read() says "not a VM based I/O requests" == "not headed for the buffer cache". This does not make sense to me although I understand something about VMIO buffers and non-VMIO buffers. I hope someone can explain the basic ideas of I/O optimization with VM object (relating to the OBJ_OPT flag and the global variable vfs_ioopt) so that I can understand the code easier. Any help is appreciated. -------------------------------------------------- Zhihui Zhang. Please visit http://www.freebsd.org -------------------------------------------------- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message