Cached file read performance

[Mark Kirkwood]

I thought it might be interesting see how 7-CURRENT did with respect to
cached file reading that we tested a while ago. Briefly recall that I'm
using a dual PIII 1.26Ghz with 2G dual channel PC133, reading a 781MB
(completely) cached file.


Redoing the same test, with the previous 6.2-PRE results included for
context, shows that we seem to be noticeably faster in 7 generally -
which is nice. There is one regression - random reads for the 64K block
size are slower than in 6.2-PRE. The results seem pretty stable...
several runs yeild pretty much same ballpark figures (enough to say
something like "10% faster sequential reads with 32K blocks")

It would be interesting to compare with 6.2-STABLE as well... but I
don't have one of the same machines running it.



The results
-----------------

FreeBSD 6.2 PRERELEASE (20061127):
--------

$ ./readtest /data0/dump/file 8192 0
random reads: 100000 of: 8192 bytes elapsed: 4.4477s io rate: 184186327
bytes/s
$ ./readtest /data0/dump/file 8192 1
sequential reads: 100000 of: 8192 bytes elapsed: 1.9797s io rate:
413804878 bytes/s

$ ./readtest /data0/dump/file 32768 0
random reads: 25000 of: 32768 bytes elapsed: 2.0076s io rate: 408040469
bytes/s
$ ./readtest /data0/dump/file 32768 1
sequential reads: 25000 of: 32768 bytes elapsed: 1.7068s io rate:
479965034 bytes/s

$ ./readtest /data0/dump/file 65536 0
random reads: 12500 of: 65536 bytes elapsed: 1.7856s io rate: 458778279
bytes/s
$ ./readtest /data0/dump/file 65536 1
sequential reads: 12500 of: 65536 bytes elapsed: 1.6611s io rate:
493158866 bytes/s


FreeBSD 7.0-CURRENT (20070722):
-------

$ ./readtest /data0/dump/file 8192 0
random reads: 100000 of: 8192 bytes elapsed: 3.8357s io rate: 213574160
bytes/s
$ ./readtest /data0/dump/file 8192 1
sequential reads: 100000 of: 8192 bytes elapsed: 1.8215s io rate:
449743176 bytes/s

$ ./readtest /data0/dump/file 32768 0
random reads: 25000 of: 32768 bytes elapsed: 1.8818s io rate: 435326721
bytes/s
$ ./readtest /data0/dump/file 32768 1
sequential reads: 25000 of: 32768 bytes elapsed: 1.5504s io rate:
528388293 bytes/s

$ ./readtest /data0/dump/file 65336 0
random reads: 12538 of: 65336 bytes elapsed: 1.9625s io rate: 417417120
bytes/s
$ ./readtest /data0/dump/file 65336 1
sequential reads: 12538 of: 65336 bytes elapsed: 1.5365s io rate:
533140236 bytes/s



regards

Mark