著者: Jakob Hirsch 日付: To: exim-users 題目: Re: [exim] How to force exim to load file with whitelist IPs into
memory
Phil Pennock, 2011-10-31 08:41:
> You've mounted the filesystem with "atime" support, which reports last
> access time. While useful, for busy file-systems this default support
> in Unix has proven to be a historical mistake (in my opinion).
>
> The only reason the disk is being affected here is because the act of
> reading the file is updating the inode with a new atime, and this needs
> to be written back to the disk. Otherwise, assuming local disk and not
> NFS, the file would sit in buffer cache and all new reads would never go
> to disk, because the cache would still be valid.
I second your opinion. atime is kind of a broken concept. OTOH, atime
updates are cached (AFAIK), so the impact should only be visible on very
busy systems with little RAM.
> Mount the filesystem noatime or move the file to a filesystem which is
> mounted noatime and see how that affects performance.
btw, Linux uses relatime by default since 2.6.30.
> CDB is probably the way to go then.
CDB (and DBM etc.) cannot be used with iplsearch. We would need a trie
data structure for that. Don't know if there are widely used standard
formats and tools for that...
