Re: NFS small files

From: Joseph Koshy (joseph.koshy_at_gmail.com)
Date: 03/09/05

  • Next message: ISP Informatique: "FreeBSD 5.3 et multiprocessor" 
    Date: Wed, 9 Mar 2005 04:15:51 +0000
To: Peter Hessler <phessler@coverity.com>

    > I should mention that copying the same directory on the nfs server takes

    Filename resolution over NFS involves multiple round-trip requests,
    one for each component of the file's pathname.

    For example, assuming that '/mnt' is an NFS mount-point, accessing a
    file named '/mnt/FreeBSD/src/sys/sys/file.h,v' results in the following
    NFS requests:

    [Edited output from ethereal]

     1 0.000000 ::1 ::1 NFS V3
    LOOKUP Call (Reply In 2), DH:0xa9a212b8/FreeBSD
    V3 Procedure: LOOKUP (3)
    what: dir
    Name: FreeBSD

    2 0.000116 ::1 ::1 NFS V3
    LOOKUP Reply (Call In 1), FH:0xcd6610c4
    Status: OK (0)

    3 0.000162 ::1 ::1 NFS V3
    LOOKUP Call (Reply In 4), DH:0xcd6610c4/src
    V3 Procedure: LOOKUP (3)
    what: dir
    Name: src

    4 0.000194 ::1 ::1 NFS V3
    LOOKUP Reply (Call In 3), FH:0x5c9e0ec6
    Status: OK (0)

    5 0.000224 ::1 ::1 NFS V3
    LOOKUP Call (Reply In 6), DH:0x5c9e0ec6/sys
    V3 Procedure: LOOKUP (3)
    what: dir
    Name: sys

    6 0.000253 ::1 ::1 NFS V3
    LOOKUP Reply (Call In 5), FH:0xb4d2113a
    Status: OK (0)

    7 0.000281 ::1 ::1 NFS V3
    LOOKUP Call (Reply In 8), DH:0xb4d2113a/sys
    V3 Procedure: LOOKUP (3)
    what: dir
    Name: sys

    8 0.000312 ::1 ::1 NFS V3
    LOOKUP Reply (Call In 7), FH:0xb0f9f738
    Status: OK (0)

    9 0.000338 ::1 ::1 NFS V3
    LOOKUP Call (Reply In 10), DH:0xb0f9f738/file.h,v
    V3 Procedure: LOOKUP (3)
    what: dir
    Name: file.h,v

    10 0.000366 ::1 ::1 NFS V3
    LOOKUP Reply (Call In 9), FH:0x58ea0f3a
    Status: OK (0)

    11 0.002220 ::1 ::1 NFS V3
    ACCESS Call, FH:0xa9a212b8
    V3 Procedure: ACCESS (4)
    object
    access: 0x3f

    I can imagine that the extra latency induced by these round-trips would be
    adding to elapsed time for your test.
      

    -- 
FreeBSD Volunteer, http://people.freebsd.org/~jkoshy
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