Date: Thu, 8 Feb 2001 16:26:27 +0100 From: Andre Albsmeier <andre.albsmeier@mchp.siemens.de> To: Cliff Sarginson <cliff@raggedclown.net> Cc: Andre Albsmeier <andre.albsmeier@mchp.siemens.de>, freebsd-questions@FreeBSD.ORG Subject: Re: minfree: Which is wrong: newfs(8) or tunefs(8) ? Message-ID: <20010208162627.A98695@curry.mchp.siemens.de> In-Reply-To: <E14Qsv4-000OAD-00@post.mail.nl.demon.net>; from cliff@raggedclown.net on Thu, Feb 08, 2001 at 03:23:38PM %2B0000 References: <E14Qsv4-000OAD-00@post.mail.nl.demon.net>
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On Thu, 08-Feb-2001 at 15:23:38 +0000, Cliff Sarginson wrote:
> I worked for a company once whose *only* technical documentation
> was a line for each program that said:
>
> "Documentation: Refer to source for more info"
Hmm, you are right. According to ffs_alloc.c I would assume
that 5% is correct:
/*
* Allocate an exact sized fragment. Although this makes
* best use of space, we will waste time relocating it if
* the file continues to grow. If the fragmentation is
* less than half of the minimum free reserve, we choose
* to begin optimizing for time.
*/
request = nsize;
if (fs->fs_minfree <= 5 ||
fs->fs_cstotal.cs_nffree >
(off_t)fs->fs_dsize * fs->fs_minfree / (2 * 100))
break;
log(LOG_NOTICE, "%s: optimization changed from SPACE to TIME\n",
-Andre
>
> :)
>
> > Regarding minfree in FFS:
> >
> > tunefs(8) says:
> >
> > threshold. Settings of 5% and less force space optimization to
> > always be used which will greatly increase the overhead for file
> > writes. Note that if the value is raised above the current usage
> >
> > newfs(8) says:
> >
> > mize the space fragmentation on the disk. If the value of min-
> > free (see above) is less than 8%, the default is to optimize for
> > space; if the value of minfree is greater than or equal to 8%,
> > the default is to optimize for time. See tunefs(8) for more de-
> > tails on how to set this option.
> >
> > So do we have to set minfree below 5% or 8% in order that space
> > optimization is used always?
> >
> > Thanks,
> >
> > -Andre
> >
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