No offense, but you probably don't want to do that. Linux' file cache
is extremely agressive and very well tuned. If the whole file isn't
staying in the file cache all the time anyway, that's because the system
is doing enough things that the memory is better used on other tasks.
If you make a RAMdisk (tmpfs) and put that file in there, you may be
causing a significant hit on the ability of the system to handle the
other tasks it might be trying to do. It'll thrash *more* on other
processes, which is going to overall _slow down_ your access to the
system, even though you've put that one file in a RAM disk.
If it's *not* doing anything else, and there is enough RAM for that file
to fit into filesystem cache, it will be based on the kernel's VFS and
VM systems. No need to explicitly force it into a RAMdisk.
In other words, the system is smart - let it figure out what to do with
its memory, or you're just going to wind up crippling some other part of
it in favor of making one thing it's doing go a little bit faster. (And
you may not make it any faster anyway - see above.)
On Tue, 2002-02-19 at 10:24, Mikes work account wrote:
> found my own answer on google,,,
>
> all about ram disks on linux.
>
> Michael C. Rock
>
> -----Original Message-----
> From: slug@lists.nks.net [mailto:slug@lists.nks.net]On Behalf Of Mikes
> work account
> Sent: Tuesday, February 19, 2002 8:44 AM
> To: slug@nks.net
> Subject: [SLUG] A ggod one for all of you,,
>
>
>
> As you may or not recall, about a year ago I had a slow system which
> required months to 'speed' up. Thanks to many of you it has been operating
> splendidly. It was not one particular issue but the sum of many that made
> the difference.
>
> We have added many programs and files to the system and as a result the
> system is again 'sluggisn'.
>
> We have one file that most of the others access when updating or printing
> reports. If I could 'stick' that file in ram in total, I could speed up my
> seeks dramatically. I recall a few years back that was possible with SCO or
> was it Unix?? I don't recall.
>
> Do any of you have any experience in keeping a data file in ram
> continuously?
>
> Michael C. Rock
>
>
>
--
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
#!/usr/bin/perl -w
$_='while(read+STDIN,$_,2048){$a=29;$b=73;$c=142;$t=255;@t=map
{$_%16or$t^=$c^=($m=(11,10,116,100,11,122,20,100)[$_/16%8])&110;
$t^=(72,@z=(64,72,$a^=12*($_%16-2?0:$m&17)),$b^=$_%64?12:0,@z)
[$_%8]}(16..271);if((@a=unx"C*",$_)[20]&48){$h=5;$_=unxb24,join
"",@b=map{xB8,unxb8,chr($_^$a[--$h+84])}@ARGV;s/...$/1$&/;$d=
unxV,xb25,$_;$e=256|(ord$b[4])<<9|ord$b[3];$d=$d>>8^($f=$t&($d
>>12^$d>>4^$d^$d/8))<<17,$e=$e>>8^($t&($g=($q=$e>>14&7^$e)^$q*
8^$q<<6))<<9,$_=$t[$_]^(($h>>=8)+=$f+(~$g&$t))for@a[128..$#a]}
print+x"C*",@a}';s/x/pack+/g;eval
usage: qrpff 153 2 8 105 225 < /mnt/dvd/VOB_FILENAME \
| extract_mpeg2 | mpeg2dec -
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