Re: Mercurial 0.3 vs git benchmarks

From: Linus Torvalds <torvalds@osdl.org>
Date: Apr 27, 2005, 21:39 UTC
Message-ID: <Pine.LNX.4.58.0504271431510.18901@ppc970.osdl.org>
In-Reply-To: <426FFFAB.1030005@tmr.com>

On Wed, 27 Apr 2005, Bill Davidsen wrote:

> 
> I said much the same in another post, but noatime is not always what I 
> really want.

"atime" is really nasty for a filesystem. I don't know if anybody noticed, but git already uses O_NOATIME to open all the object files, because if you don't do that, then just looking at a full kernel tree (which has more than a thousand subdirectories) will cause nasty IO patterns from just writing back "atime" information for the "tree" objects we looked up.

So you can do (and git does) selective atime updates. It just requires a small amount of extra care.

> How about a "nojournalatime" option, so the atime would be 
> updated at open and close, but not journaled at any other time.

Probably a good idea.

		Linus