from your description is looks like there is an issue with the machine. We do not run with CentOS in our testing environment so this isnt going to be something that we can provide more details on The BDB code base is the same on all those machines and if you have one machine where the performance is different, then our recommendation is to look at the machines are figure out how they are different. File system behavior can play a large part in IO performance.
I try to find out the different part, but it does not work. So i try to find out how many parameters to affect IO performance.
1、BDB parameters: I just set cache_size, how does this to effect db::put performance? any other parameters you suggest to set to improve the performance?
2、OS parameters : can you list some parameters that may affect the performance? Specilally in linux.
I has two machine, both in CentOS, but os in one of them has been customized. Before customize, application works well, but bad after customize.
pagesize, parameters with command ulimit -a, most parameters with sysctl are the same, and both ext3, blocksize is 4K.
I have no idea which parameters should i fouce on. any suggestion is welcome.