Mike Matrigali <[EMAIL PROTECTED]> wrote on 09/03/2004 09:21:58 AM: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > is your log preallocated or not?
The log files are normally pre-allocated. I do not delete the files before or after a test, so files get reused. I have noticed that the test actually runs a little faster when it creates new files, and we have yet to explain that. > Are your writes block bounded? The block size is configurable. The default block is 2K bytes. Each block is written when it becomes full. The channel.force() is called when the write queue is empty, so if the system is lightly loaded, force() is called for each buffer, but if system is loaded, force() gets called less frequently. Depending on the hardware and OS, the average number of buffers that are forced ranges from 1.5 to 8 or 9. My measurements do not include any db IO. The test driver only logs XA protocol records, with zero think time. The objective is to determine that the log will not be a bottleneck for the TM. When I tested with "rwd" I did not change any logic, so the batching of writes into a single force() was still going on, and the force() probably was not needed because the writes were already forced by the "rwd" mode. I guess I should modify that code to get a better number when using "rwd". Michael Giroux
