[mythtv-users] Will moving to DDR-400 memory from DDR-333 improve performance?
Chris Pinkham
cpinkham at bc2va.org
Mon Oct 30 21:47:05 UTC 2006
* On Mon Oct 30, 2006 at 02:10:38PM -0500, Brian J. Murrell wrote:
> Of course not. But do you really think the kernel and a few linux
> utilities are gobbling up the hundreds and hundreds of MB of ram that we
> are seeing?
Where are these hundreds of MB you are seeing?
Here's samples from my 2 backends and my main frontend. Between all three
of them I'm barely using 165MB and that's 2 copies of mythbackend and one
copy of mythfrontend. Command being run is:
ps auxw | egrep "mythfront|mythback|RSS" | grep -v grep ; echo ; free
Master backend w/ 3 AverMedia M179 cards:
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
mythtv 2074 0.1 11.8 248100 30244 pts/2 S Oct28 3:27 mythbackend
total used free shared buffers cached
Mem: 255208 245296 9912 0 31932 111540
-/+ buffers/cache: 101824 153384
Swap: 265032 2928 262104
OK, so we're using ~30MB there for mythbackend.
Now the slave backend with 2 air2pc ATSC HD cards:
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
mythtv 28147 1.4 4.0 206800 20920 pts/2 S Oct28 42:24 mythbackend
total used free shared buffers cached
Mem: 516500 189156 327344 0 18868 63956
-/+ buffers/cache: 106332 410168
Swap: 265064 0 265064
OK, using a whopping 20MB there.
Now the main frontend:
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
mythtv 5717 3.6 22.7 242300 116720 pts/4 S Oct08 1167:51 mythfrontend
total used free shared buffers cached
Mem: 512668 503240 9428 0 60868 169424
-/+ buffers/cache: 272948 239720
Swap: 265064 55420 209644
So, using about 116MB there for a grand total of 166MB on all three boxes.
Just because the VSZ of a program is 260MB doesn't mean it's using that, look
at the swap numbers in my 'free' command. On the slave backend where VSZ is
200MB, I don't have anything in swap at all, so just because VSZ is 200MB and
RSS is 20MB it doesn't mean that I'm going to have to swap in 180MB of data
or program the next time that something wants to use mythbackend.
> It just seems that 0.20 came with a much bigger footprint than 0.19 had.
> I just wonder why. Perhaps there is no reasonable explanation and there
> is a bug somewhere.
Perhaps there are a lot of people out there jumping to conclusions about
how much memory Myth is actually using.
--
Chris
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