db-derby-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Michael.Gir...@objectweb.org
Subject Re: java1.4.2 "rws" mode - log write performance - OSX numbers
Date Wed, 15 Sep 2004 20:35:26 GMT
Jan Hlavatý <hlavac@code.cz> wrote on 09/15/2004 12:35:40 PM:

> Most probably because the implementation does not what it is supposed to 
do,
> and does ordinary "rw" mode instead.

I don't think so.  I added a couple of tests to the original code.  #16 is 
the same as
#15 with a channel.force(false) added to each write.  The total bandwidth 
is 
less than 1/2 that of #15, suggesting that Jan is correct.

But test #17 uses "rw" without a force, (which is what I think Jan 
suggested)
and for this test, the write bandwidth is 255 MB/s, 10x faster than #16 
and
4x faster than #15.

I'm not really sure what can be concluded from this.  How can we be 
certain
that "rwd" is honoring the guarantee not to return till data is on media?

Michael Giroux, Objectweb.org

-----------------------------------------------------------------------
15. Testing preallocated file using direct buffer + FileChannel "rwd"
-----------------------------------------------------------------------
       Chunk size: 4228 bytes
            Count: 5000
       Total time: 329 ms
Writes per second: 15197.568 writes/s
   Time per chunk: 0.066 ms
  Write bandwidth: 61.0MB/s

----------------------------------------------------------------------------
16. Testing preallocated file using direct buffer + FileChannel "rwd" 
force(false)
----------------------------------------------------------------------------
       Chunk size: 4228 bytes
            Count: 5000
       Total time: 859 ms
Writes per second: 5820.722 writes/s
   Time per chunk: 0.172 ms
  Write bandwidth: 23.0MB/s

------------------------------------------------------------------------------
17. Testing preallocated file using direct buffer + FileChannel "rw" no 
force
------------------------------------------------------------------------------
       Chunk size: 4228 bytes
            Count: 5000
       Total time: 79 ms
Writes per second: 63291.139 writes/s
   Time per chunk: 0.016 ms
  Write bandwidth: 255.0MB/s

C:\GIROUX\HOWL\Derby Benchmark>

Mime
View raw message