hdparm -tT reports "suspicious results" ???

From: Chuck Ebbert (76306.1226@compuserve.com)
Date: Sun Apr 06 2003 - 08:13:18 EST


  Real-world benchmarks show I am getting about 30-32 MB/sec from my
IDE disks on 2.4.21-pre6: raid1 rebuild reports 32MB/sec and copying
a 1GB file to /dev/null on a newly-mounted fs takes 33 sec. I have
moved the disk to another computer that is almost 100% identical
except for CPU (PPro 200 vs. PII ODP/333) and now hdparm says 24MB/sec
but I am still getting 30-32 real world on the PPro 200. The below
results are from the PII Overdrive (I have not tested real-world
on 2.5 but notice how much slower hdparm reports its speed.) What
does "suspicious" mean here?

# uname -a
Linux d2 2.4.21-pre6 #3 Fri Apr 4 18:22:11 EST 2003 i686 unknown
# hdparm -tT /dev/hde

/dev/hde:
 Timing buffer-cache reads: 128 MB in 2.50 seconds = 51.20 MB/sec
 Timing buffered disk reads: 64 MB in 2.15 seconds = 29.77 MB/sec
Hmm.. suspicious results: probably not enough free memory for a proper test.
#
Script done on Fri Apr 4 20:49:01 2003
Script started on Fri Apr 4 20:52:03 2003
# uname -a
Linux d2 2.4.20 #1 Fri Apr 4 17:33:07 EST 2003 i686 unknown
# hdparm -tT /dev/hde

/dev/hde:
 Timing buffer-cache reads: 128 MB in 2.62 seconds = 48.85 MB/sec
 Timing buffered disk reads: 64 MB in 2.35 seconds = 27.23 MB/sec
Hmm.. suspicious results: probably not enough free memory for a proper test.
#
Script done on Fri Apr 4 20:52:46 2003
Script started on Fri Apr 4 20:56:54 2003
# uname -a
Linux d2 2.5.66 #11 Sat Mar 29 21:14:17 EST 2003 i686 unknown
# hdparm -tT /dev/hde

/dev/hde:
 Timing buffer-cache reads: 128 MB in 2.66 seconds = 48.14 MB/sec
 Timing buffered disk reads: 64 MB in 3.90 seconds = 16.41 MB/sec
# cat /proc/meminfo
MemTotal: 191956 kB
MemFree: 170728 kB
Buffers: 4244 kB
Cached: 9548 kB
SwapCached: 0 kB
Active: 7908 kB
Inactive: 7764 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 191956 kB
LowFree: 170728 kB
SwapTotal: 262040 kB
SwapFree: 262040 kB
Dirty: 8 kB
Writeback: 0 kB
Mapped: 3668 kB
Slab: 3932 kB
Committed_AS: 2616 kB
PageTables: 292 kB
ReverseMaps: 2832

Configuration (now):
 Dell Optiplex GXPro (MPS 1.4)
      1 PPro 200, Uniprocessor IO-APIC kernel
      Promise Ultra 100TX2
              2 x Maxtor 4K060H3 (60GB 5400RPM)
              (1 drive per channel)

--
 Chuck
 I am not a number!
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This archive was generated by hypermail 2b29 : Mon Apr 07 2003 - 22:00:27 EST