Re: [PATCH 00/23] per device dirty throttling -v8

Arjan van de Ven
2007-08-05T18:10:40Z

>
> In addition, big server boxes are usually not reading a huge *number*
> of files per second. The place where you see this as a problem is (a)
> compilation, thanks to huge /usr/include hierarchies (and here things
> have gotten worse over time as include files have gotten much more
> complex than in the early Unix days), and (b) silly desktop apps that
> want to scan huge numbers of XML files or who want to read every
> single image file on the desktop or in an open file browser window to
> show c00l icons. Oh, and I guess I should include Maildir setups.
>
> If you are always reading from the same small set of files (i.e., a
> database workload), then those inodes only get updated every 5 seconds
> (the traditional/default metadata update sync time, as well as the
> default ext3 journal update time), it's no big deal. Or if you are
> running a mail server, most of the time the mail queue files are
> getting updated anyway as you process them, and usually the mail is
> delivered before 5 seconds is up anyway.

it's just one of those things that get compounded with journaling
filesystems though..... a single async write that happens "sometime in
the future" is one thing... having a full transaction (which acts as
barrier and synchronisation point) is something totally worse.

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