Subject: Re: Adding -nomtime to the kernel
To: Darren Reed <>
From: Thor Lancelot Simon <>
List: tech-kern
Date: 09/15/2007 20:27:39
On Sat, Sep 15, 2007 at 04:28:16PM -0700, Darren Reed wrote:
> Playing around with a filesystem based database, such as postgres,
> is an interesting experience in trying to keep it running fast...some
> of the tweaks are db related, some not...
> For example, if the db is serving queries every second or so,
> then there's a lot of "atime" updates that happen and mounting the
> filesystem with -noatime has a noticable impact on performance.
> Having done that, I'm wondering if it makes sense for NetBSD
> to support -nomtime as well.  I'm not sure what impact this will
> have on postgres's operation (does it depend on file modification
> timestamp changes?) but I'm semi-willing to give it a shot.

I tried this a long time ago; it helped my application (a Usenet
news spool) only a little compared to the boost from noatime, and
it broke a lot of stuff in the system.  But for special-purpose file

I let Kirk talk me out of checking it in with noatime, but in retrospect,
Unix gives you enough rope, so I suspect we probably should here too.