Re: More on 2.1.65 slowdown (disc thrashing)

Janos Farkas (Janos.Farkas-#9rRLr1CZMewdpjVzT/wbT.thLoG@lk9qw.mail.eon.ml.org)
Fri, 21 Nov 1997 14:44:36 +0100


On Fri, Nov 21, 1997 at 09:17:08PM +1100, Richard Gooch wrote:
> Hi, all. To followup on my previous message where I reported a
> slowdown and increased disc head movement when running latex2html on a
> document, I've had a look at what perl does and distilled the essence.

> fsync ( fileno (fp) );

Just recently, fsync has been changed to unconditionally call sync(),
because it has been found that fsync on very large files can take
enormous times (even hours!). This is because it wanted to sync all
the indirect blocks in addition to the changed data blocks, so it
could be unbearably slow. Now, it seems making this to sync() always
is not too wise either. Possibly the best thing would be to do
this only on substantially large files (>64M or so). Maybe making
fdatasync() work in the same shot would be nice too, before the VFS
interface will be frozen...

-- 
Janos - Don't worry, my address is real.  I'm just bored of spam.