Date: Mon, 7 Jun 1999 14:33:07 -0400 (EDT) From: Zhihui Zhang <zzhang@cs.binghamton.edu> To: freebsd-hackers@freebsd.org Subject: help with I/O optimization with object Message-ID: <Pine.GSO.3.96.990607141929.12278A-100000@sol.cs.binghamton.edu>
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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
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