It would be interesting to see similar tests in which the
filesystems were mounted such that the inode access time
is not updated.


D

* On Fri, Mar 23, 2001 at 01:22:58AM -0700, Kevin Buettner wrote:
> On Mar 22,  1:47pm, Kevin Buettner wrote:
> 
> > If anyone's interested, I could also run these tests on the same box
> > using NetBSD 1.5, Solaris 8, and Unixware 7.  It might be
> > interesting to see how the commercial OSes do...
> 
> Well, as it turned out, I was interested in seeing whether other
> implementations of Unix use memory to cache file data.  I was also
> interested in seeing how well these other OSes make use of this
> cache.  Below are my findings...
> 
> ...........................................................................
> 
> The table below shows the time (in seconds) taken to run the following
> command back-to-back (i.e. twice in a row) on various OSes:
> 
>     time find linux-2.4.2 -type f -print | xargs wc > /dev/null
> 
> This test measures how well the OS uses extra memory to cache file
> data.  The test data are the sources to the stock Linux 2.4.2 kernel
> available from ftp.kernel.org.  The test data takes up roughly 108MB
> of disk space.
> 
> Hardware is 1.1GHz Athlon w/ 768 MB memory.  There are two disks in
> the machine.  Both are 7200 RPM EIDE drives made by Western Digital. 
> One drive is 30GB; the other is 40GB.  The 40GB drive was used for the
> Solaris 8 and NetBSD 1.5 tests; the 30GB drive was used for the other
> tests.
> 
>                 | Real #1 | User #1 |  Sys #1 | Real #2 | User #2 |  Sys #2 |
> ----------------+---------+---------+---------+---------+---------+---------+
> RH Wolverine    |   19.85 |    1.43 |    0.87 |    1.65 |    1.21 |    0.44 |
> ----------------+---------+---------+---------+---------+---------+---------+
> FreeBSD 4.2 (1) |   21.46 |    1.59 |    1.30 |    7.24 |    1.52 |    0.74 |
> ----------------+---------+---------+---------+---------+---------+---------+
> FreeBSD 4.2 (2) |   31.00 |    1.43 |    1.25 |    4.93 |    1.45 |    0.75 |
> ----------------+---------+---------+---------+---------+---------+---------+
> NetBSD 1.4      |   22.87 |    1.19 |    1.06 |   22.38 |    1.19 |    1.07 |
> ----------------+---------+---------+---------+---------+---------+---------+
> NetBSD 1.5      |   26.38 |    1.21 |    1.07 |   24.61 |    1.17 |    0.96 |
> ----------------+---------+---------+---------+---------+---------+---------+
> Unixware 7      |   40.86 |    1.58 |   17.26 |    2.40 |    1.28 |    1.02 |
> ----------------+---------+---------+---------+---------+---------+---------+
> Solaris 8       |   55.51 |    1.92 |    2.09 |    2.94 |    1.82 |    1.04 |
> ----------------+---------+---------+---------+---------+---------+---------+
> 
> Notes:
>  (1) Using ext2fs for the filesystem
>  (2) Using ufs for the filesystem
> 
> uname -a data
> -------------
> Wolverine:
> Linux mesquite 2.4.1-0.1.9 #1 Wed Feb 14 22:15:15 EST 2001 i686 unknown
> 
> FreeBSD 4.2:
> FreeBSD mesquite.lan 4.2-RELEASE FreeBSD 4.2-RELEASE #2: Sun Mar 11 11:18:15 MST 2001     root@mesquite.lan:/usr/src/sys/compile/MESQUITE  i386
> 
> NetBSD 1.4:
> NetBSD mesquite 1.4 NetBSD 1.4 (GENERIC) #0: Fri May  7 12:27:31 PDT 1999     perry@cynic.cynic.net:/usr/src/sys/arch/i386/compile/GENERIC i386
> 
> NetBSD 1.5:
> NetBSD mesquite.lan 1.5 NetBSD 1.5 (GENERIC) #1: Sun Nov 19 21:42:11 MET 2000     fvdl@sushi:/work/trees/netbsd-1-5/sys/arch/i386/compile/GENERIC i386
> 
> Unixware 7:
> UnixWare mesquite 5 7.1.1 i386 x86at SCO UNIX_SVR5
> 
> Solaris 8:
> SunOS mesquite 5.8 Generic_108529-03 i86pc i386 i86pc
> 
> Additional notes and observations
> ---------------------------------
> 
> With the exception of FreeBSD 4.2, I'm using the stock kernel from the
> install of each OS.  I have not done any system tuning.  (The FreeBSD
> kernel was recompiled in order to get ext2fs support.)
> 
> The "Real #1" numbers should be taken with a grain of salt.  The
> machine in question is a multi-boot machine and I had to copy over the
> test data to the partition where the OS resides.  It is well known
> that different portions (usually inner tracks vs. outer tracks) of a
> disk perform differently.  (My understanding is that the outer tracks
> give better performance and that the difference in performance between
> the inner and outer tracks can be quite dramatic.  See
> www.storagereview.com for more info.)
> 
> The important number for this test is the "Real #2" value.  The above
> tests shows that Linux, FreeBSD, Unixware 7, and Solaris 8 all use
> memory to cache filesystem data.  Neither of the NetBSD releases that
> I tested appear to use memory as a cache since the wall clock
> performance for the second test was virtually identical to the first. 
> Also, FreeBSD doesn't do as good a job as one might expect, though it
> does do slightly better when using it's own native filesystem (UFS). 
> It's interesting to note that, in the first test, FreeBSD completed
> roughly 9.5 seconds faster when using an ext2 filesystem as opposed to
> a UFS filesystem.  (But again, see the caveat in the previous
> paragraph; this number could be entirely due to the location where
> the data resides on disk.)
> 
> I repeated some of the more surprising tests (in particular, the Linux
> and FreeBSD tests) more than once and obtained virtually identical
> results in the subsequent trials.  I should also note that each trial
> (consisting of the two back to back tests) was run immediately after a
> fresh boot of the OS under consideration.  The reason for doing this
> was to make sure that as much of the machine's memory as possible was
> free to use for caching file data.
> 
> Comments?
> 
> Kevin
> 
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