data from blktrace: read speed V.S. write speed Post: 302365134

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Special Forums Hardware Filesystems, Disks and Memory data from blktrace: read speed V.S. write speed Post 302365134 by W.C.C on Monday 26th of October 2009 05:45:15 AM

10-26-2009

Registered User

data from blktrace: read speed V.S. write speed

I analysed disk performance with blktrace and get some data:
read:

Code:

  8,3    4     2141     2.882115217  3342  Q   R 195732187 + 32 [cat]
  8,3    4     2142     2.882116411  3342  G   R 195732187 + 32 [cat]
  8,3    4     2144     2.882117647  3342  I   R 195732187 + 32 [cat]
  8,3    4     2145     2.882118965  3342  D   R 195732187 + 32 [cat]
  8,3    4     2149     2.884145702     0  C   R 195732187 + 32 [0]

write:

Code:

  
  8,3    4    43622     5.305507398  3436  Q   W 17805895 + 8 [bash]
  8,3    4    43623     5.305508277  3436  G   W 17805895 + 8 [bash]
  8,3    4    43624     5.305508574  3436  I   W 17805895 + 8 [bash]
  8,3    2      414     5.306695591     0  D   W 17805895 + 16 [swapper]
  8,3    2      418     5.307020642     0  C   W 17805895 + 16 [0]

And, d2c time of one read request is 0.002026737s. On the other hand, d2c time of one write request is 0.000325051s. It show: read time > write time. Is it right? why? I have no idea.

W.C.C

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LEARN ABOUT CENTOS

verify_blkparse

VERIFY_BLKPARSE(1)														VERIFY_BLKPARSE(1)

NAME

       verify_blkparse - verifies an output file produced by blkparse

SYNOPSIS

       verify_blkparse <filename>

DESCRIPTION

       Verifies an output file from blkparse. All it does is check if the events in the file are correctly time ordered. If an entry is found that
       isn't ordered, it's dumped to stdout.

AUTHORS

       blkparse was written by Jens Axboe, Alan D. Brunelle and Nathan Scott.  This man page was created from the blktrace  documentation  by  Bas
       Zoetekouw.

REPORTING BUGS

       Report bugs to <linux-btrace@vger.kernel.org>

COPYRIGHT

       Copyright (C) 2006 Jens Axboe, Alan D. Brunelle and Nathan Scott.
       This   is   free   software.    You   may   redistribute   copies   of	it   under   the   terms   of	the  GNU  General  Public  License
       <http://www.gnu.org/licenses/gpl.html>.	There is NO WARRANTY, to the extent permitted by law.
       This manual page was created for Debian by Bas Zoetekouw.  It was derived from the documentation provided by the  authors  and  it  may	be
       used, distributed and modified under the terms of the GNU General Public License, version 2.
       On Debian systems, the text of the GNU General Public License can be found in /usr/share/common-licenses/GPL-2.

SEE ALSO

       btrace (8), blktrace (8), blkparse (1), blkrawverify (1), btt (1)

blktrace git-20070306202522					  March  6, 2007						VERIFY_BLKPARSE(1)

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