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List:       cyrus-devel
Subject:    Re: MMAP performance and using mmap writes
From:       Дилян_ =?UTF-8?Q?=D0=9F=D0=B0=D0=BB=D0=B0=D
Date:       2018-11-30 14:30:44
Message-ID: 301a947e9606482e3a30a358584d826ff8c2e7ae.camel () aegee ! org
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Hello,

> > 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?

Greetings
  Dilyan


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