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Date:      Thu, 3 Jun 1999 10:40:10 -0400 (EDT)
From:      Zhihui Zhang <zzhang@cs.binghamton.edu>
To:        freebsd-hackers@freebsd.org
Subject:   The choice of MAXPHYS
Message-ID:  <Pine.GSO.3.96.990603101914.28480A-100000@sol.cs.binghamton.edu>

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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



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