MMAP performance and using mmap writes

Дилян Палаузов dilyan.palauzov at
Fri Nov 30 09:30:44 EST 2018


> > 3: if your DB is larger than RAM, writing thru mmap is slower than using write() syscalls. Whenever you
> > access a page for the first time, the OS will page it in. This is a wasted I/O if all you're doing is
> > overwriting the page with new data.
> I doubt it... especially now we're running on servers with 256Gb of data.  These databases are usually under a gigabyte in size.  I also don't think we ever overwrite a page without reading from it first - we're usually updating pointers which we've just had to read.

Are there recommendations on RAM for running cyrus imap, that reflect
this aspect?


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