Date: Sun, 29 Oct 1995 20:59:04 -0800 From: "Amancio Hasty Jr." <hasty@rah.star-gate.com> To: Julian Elischer <julian@ref.tfs.com> Cc: hackers@FreeBSD.ORG, Jim Lowe <james@miller.cs.uwm.edu> Subject: Re: Buffer cache , lmbench part 3 Message-ID: <199510300459.UAA10767@rah.star-gate.com> In-Reply-To: Your message of "Sun, 29 Oct 1995 20:35:01 PST." <199510300435.UAA09703@ref.tfs.com>
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>>> Julian Elischer said:
> How do you know it's buffer_cache?
Cause that's Jim said ... Not sure if Jim recorded the space launch
on tape. However, I am sure that he can try to record something else
and see if he gets similar results. Currently, I am little handicap because
I can't capture video on FreeBSD , argh... and the video capture at
least under Windows sucks . Hopefully, in the near future I will
be able to get my Diamond S3 968 + mpeg/video capture daugther card
working on FreeBSD.
Tnks for the tip!!
Amancio
> you could put the 'sync' (update) frequency to 1
> sysctl -w kern.update=1
> (I think)
> and try again..
> (I presume he has it on tape....)
> you don't want to go synchronous
> but you don't want to be so asynchronous that the ram fills up
> and you end up waiting on disk..
>
>
> try this....
>
>
> >
> >
> > Jim Lowe recorded the last space shuttle launch on his FreeBSD box;however
,
> > he ran into a minor gotcha the buffer cache. If you want to see the
> > buffer cache in action just play the mpeg movie and look for pauses on
> > on the movie. So the question now is: Is the buffer cache tuneble to
> > avoid this kind of behavior?
> >
> > I was thinking that video capture without compression eats up enourmous
> > amount of disk space so it would not be too unconceivable to bypass the
> > file system and buffer cache and just do raw I/O to the disk.
> >
> > Here is a pointer to Jim's mpeg version of the space shuttle launch it
> > is about 1.7mb and the original was 300MB :
> >
> > ftp://ftp.cs.uwm.edu/pub/shuttle_gifs/sts73.launch.mpg.
> >
> > Enjoy,
> > Amancio
> >
> >
> >
>
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