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Re: BerkeleyDB performance on Linux
This is interesting. Did you test performance under other workloads ?
With this patch, a slapd that occupies 6.8GB on a system with 8GB of
RAM can run continuously without swapping, delivering a sustained
11,500 authentications per second. Without the patch, swapping starts
when the process hits the 4.5GB mark (because over 3GB of buffer
cache is in use), and performance drops to only *hundreds* of
authentications per second.
Reason I ask is that every time I've tried O_DIRECT in the past performance
suffered (significantly) in the case where I/O is being done (I suspect
due to reduced
concurrency because the application must block in cases where it
wouldn't have when using OS buffering). Other database productst that
I keep track of (e.g. Postgresql) report similar findings.